@article { ISI:000270362100043, title = {Carbon nanofiber with selectively decorated pt both on inner and outer walls as an efficient electrocatalyst for fuel cell applications}, journal = {Journal of Physical Chemistry C}, volume = {113}, number = {40}, year = {2009}, month = {OCT}, pages = {17572-17578}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A novel electrocatalyst, with excellent Pi dispersion oil the inner and outer wall of a carbon nanofiber (CNF) was prepared by a modified polyol process in which both surface tension and polarity characteristics of the medium were properly adjusted to favor solution entry into the tubular region by capillary filling and homogeneous wetting of the inner wall surface by the solvents. The pristine CNF, which possesses an inherently active inner wall surface and inactive outer Wall surface, led to selective Pt deposition along the inner wall, whereas activation of the outer wall with chemical functionalization resulted in excellent dispersion of Pt along both inner and outer walls. Structural and morphological characterizations using high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) revealed that when Pt could be dispersed along the inner as well as the Outer walls of CNF, the Pt particle size decreased to almost half as compared to the one With Pt decoration only along a single wall of the Substrate material. Further, electrochemical studies using cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements revealed enhanced methanol oxidation and oxygen reduction properties, respectively. The electrochemical active area obtained for the catalyst with both inner and outer wall Pt decoration wits nearly two times higher than that corresponding to the one with only inner wall Pt decoration. Similarly, the rate constant for the oxygen reduction reaction displayed by this sample was four times higher in comparison with the sample prepared by Utilizing only one wall for Pt decoration.

}, issn = {1932-7447}, doi = {10.1021/jp9042655}, author = {Balan, Beena K. and Unni, SreeKuttan M. and Kurungot, Sreekumar} } @article { ISI:000266821100020, title = {Design of an "allsolid-state{\textquoteright}{\textquoteright} supercapacitor based on phosphoric acid doped polybenzimidazole (PBI) electrolyte}, journal = {Journal of Applied Electrochemistry}, volume = {39}, number = {7}, year = {2009}, month = {JUL}, pages = {1097-1103}, publisher = {SPRINGER}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

The effectiveness of phosphoric acid doped polybenzimidazole as a polymer electrolyte membrane to fabricate an all solid-state super capacitor has been explored using hydrous RuO(2)/carbon composite electrodes (20 wt.\%) of surface area 250 m(2) g(-1) with many intrinsic advantages. The electrochemical evaluation of these super capacitors through cyclic voltammetry, charge/discharge and impedance measurements demonstrate the utility of this type of thin, compact and flexible supercapacitor capable of functioning at 150 degrees C to yield a maximum capacitance of about 290 F g(-1) along with a life of more than 1,000 cycles. A power density of 300 W kg(-1) and energy density of 10 Wh kg(-1) have been accomplished although the equivalent series resistance (ESR) of about 3.7 Omega needs to be reduced further for high rated applications.

}, keywords = {Electrochemical characterization, Electrochemical supercapacitor, Energy storage device, PBI electrolyte, RuO(2)/carbon composite}, issn = {0021-891X}, doi = {10.1007/s10800-008-9764-3}, author = {Rathod, Dhanraj and Vijay, Meenu and Islam, Md. Nazrul and Kannan, Ramaiyan and Kharul, Ulhas K. and Kurungot, Sreekumar and Pillai, Vijayamohanan} } @article { ISI:000268138400070, title = {Domain size manipulation of perflouorinated polymer electrolytes by sulfonic acid-functionalized MWCNTs to enhance fuel cell performance}, journal = {Langmuir}, volume = {25}, number = {14}, year = {2009}, month = {JUL}, pages = {8299-8305}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The application of sulfonic acid-functionalized multiwalled (s-MWNT) carbon nanotubes to manipulate the hydrophilic domain size of Nafion membranes is explored here as an option for tuning the proton conductivity of polymer electrolyte membranes for hydrogen-oxygen fuel cells. The electrochemical impedance experiments provide preliminary evidence of increased proton conductivity, while small-angle X-ray scattering measurements line. out enhanced ionic cluster domain size in these composite membranes as the central reason for higher conductivity (70 angstrom for the optimum composite membrane vs 50 angstrom for Nafion 115) values. Scanning electrochemical microscopy indicates synergistic interaction between the sulfonic acid functional groups present in the Nation membrane and those on the nanotube surface. More interestingly, the nanotube-tailored Nafion membranes ameliorate the performance of fuel cells as confirmed by measurements at a sin le-cell level, which reveal a maximum power density of 380 mW cm(-2), higher than those of Nafion 115 (250 mW cm(-2)) and recast Nafion (230 mW cm-2) membranes. Thus, in addition to providing an elegant means of controlling the ionic cluster size, the strategic approach of using CNT both as an anchoring backbone for -SO(3)H groups to enrich proton conductivity and as a blending agent to improve the mechanical characteristics of the Nafion phase might be helpful in alleviating many critical problems associated with the use of commercial Nafion membranes.

}, issn = {0743-7463}, doi = {10.1021/la9005218}, author = {Kannan, Ramaiyan and Parthasarathy, Meera and Maraveedu, Sreekuttan U. and Kurungot, Sreekumar and Pillai, Vijayamohanan K.} } @article { ISI:000280021000011, title = {Artificially designed membranes using phosphonated multiwall carbon nanotube-polybenzimidazole composites for polymer electrolyte fuel cells}, journal = {Journal of Physical Chemistry Letters}, volume = {1}, number = {14}, year = {2010}, month = {JUL}, pages = {2109-2113}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The ability of phosphonated carbon nanotubes to offer an unprecedented approach to tune both proton-conductivity and mechanical stability of hybrid polymer electrolytes based on the polybenzimidazole membrane is demonstrated for fuel cell applications. The covalent attachment between the amino group of the 2-aminoethylphosphonic acid precursor and CNTs has been confirmed by NMR and IR experiments, while EDAX analysis indicates that one out of every 20 carbon atoms is in the CNT is functionalized. Proton conductivity of the composite membrane shows a remarkable 50\% improvement in performance while a maximum power density of 780 and 600 mW cm(-2) is obtained for the composite and pristine membranes, respectively. Finally, the ultimate strength determined for the composite and pristine membranes is 100 and 65 MPa, respectively, demonstrating the superiority of the composite. This study opens up a new strategy to systematically tune the properties of polymer electrolytes for special applications by using appropriately functionalized CNTS.

}, issn = {1948-7185}, doi = {10.1021/jz1007005}, author = {Kannan, Ramaiyan and Aher, Pradnya P. and Palaniselvam, Thangavelu and Kurungot, Sreekumar and Kharul, Ulhas K. and Pillai, Vijayamohanan K.} } @article { ISI:000280145000055, title = {High aspect ratio nanoscale multifunctional materials derived from hollow carbon nanofiber by polymer insertion and metal decoration}, journal = {Chemical Communications}, volume = {46}, number = {30}, year = {2010}, month = {JUN}, pages = {5590-5592}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A novel high aspect ratio material which can simultaneously display multiple functions such as proton and electron conductivity and electrocatalytic activity has been developed by incorporating both platinum nanoparticles and phosphoric acid doped polybenzimidazole along the inner and outer surfaces of a hollow carbon nanofiber.

}, issn = {1359-7345}, doi = {10.1039/c0cc00571a}, author = {Balan, Beena K. and Kale, Vinayak S. and Aher, Pradnya P. and Shelke, Manjusha V. and Pillai, Vijayamohanan K. and Kurungot, Sreekumar} } @article { ISI:000281129100046, title = {High pt utilization electrodes for polymer electrolyte membrane fuel cells by dispersing pt particles formed by a preprecipitation method on carbon {\textquoteleft}{\textquoteleft}polished{\textquoteright}{\textquoteright} with polypyrrole}, journal = {Journal of Physical Chemistry C}, volume = {114}, number = {34}, year = {2010}, month = {SEP}, pages = {14654-14661}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Pt utilization on carbon black (CB) has been significantly improved by initially utilizing polypyrrole (PPy) as a moiety to {\textquoteleft}{\textquoteleft}polish{\textquoteright}{\textquoteright} the carbon surface and subsequently by dispersing Pt particles formed by a preprecipitation process to minimize their migration into the geometrically restricted areas of the carbon surface. This process strategy has helped to significantly extend the triple-phase boundary as a greater number of Pt particles comes in direct contact with Nafion, leading to a substantial improvement in the overall catalyst utilization. Preliminary analyses such as IR, thermogravimetric analysis, and N(2) sorption confirmed the presence of PPy on the surface. Approximately 50\% reduction in the surface area of CB after the controlled in situ polymerization of pyrrole monomer on the carbon surface indicated preferential filling and coverage of pores and other geometrically restricted pockets of carbon surface. On the other hand, by converting Pt into colloids in the preprecipitation method prior to their reduction, the platinum particles are forced to stay on the hybrid support; a major part of which otherwise would have been migrated into the surface pores and defect sites. Platinum particle size on these hybrid supports is 2 times higher than the catalyst prepared by polyol process. However, the electroactive surface area and mass activity are 2 times higher than that of the Pt particles prepared by polyol on hybrid material and are also significantly higher than that of the conventional electrocatalysts prepared by the polyol method. At 0.8 V, the kinetic current density (j(k)) of Pt/C-PPy-Pre obtained from the Koutecky-Levich plot is 1.5 and 2.5 times higher than that of catalysts prepared by the polyol method on PPy-coated carbon and Vulcan XC-72 carbon, respectively. Almost 210 and 160 mW cm(-2) improvement for the maximum power density, respectively with oxygen and air, was obtained with the modified system in comparison to the conventional system when the single cell evaluations were carried out at 60 degrees C with a Pt loading of 0.5 mg cm(-2) in the anode and cathode sides. This enhancement in the cell performance under the two different oxygen partial pressure conditions clearly emphasizes the improved oxygen reduction reaction (ORR) and mass-transfer characteristics of the hybrid electrode material compared to the other catalysts.

}, issn = {1932-7447}, doi = {10.1021/jp104664t}, author = {Unni, SreeKuttan M. and Dhavale, Vishal M. and Pillai, Vijayamohanan K. and Kurungot, Sreekumar} } @article { ISI:000275985700041, title = {Pt-MoOx-carbon nanotube redox couple based electrocatalyst as a potential partner with polybenzimidazole membrane for high temperature polymer electrolyte membrane fuel cell applications}, journal = {Electrochimica Acta}, volume = {55}, number = {8}, year = {2010}, month = {MAR}, pages = {2878-2887}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

A redox couple based electrocatalyst comprising of Pt-Multi Wall Carbon NanoTube (Pt-MWCNT) promoted with molybdenum oxide (MoOx, 2 \< x \< 3) nanoparticles was prepared. The objective was to effectively organize the Pt-MoOx interface on the smooth MWCNT surface to overcome the practical difficulties associated with establishing such interface with Pt dispersed on carbon morphologies possessing surface irregularities. The present study revealed the importance of stringent controlling of the additive level for maintaining a balanced bifunctional behavior of the catalyst combination through the synergistic effects by the components and the need of a proton conducting membrane operable at high temperature to get better output from the Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems. An indigenously developed polybenzimidazole (PBI) membrane was used to fabricate a membrane electrode assembly (MEA) as it can be operated at higher temperatures compared to that of Nafion membranes. MoOx additive level was carefully controlled by monitoring the active Pt area by cyclic voltammetry. All prepared electrocatalysts were characterized by using HRTEM, XRD and XPS to get information on dispersion and morphology, crystalinity and oxidation state of different elements, respectively. The system prepared with 5\% MoOx addition with respect to Pt (hereafter Pt-MoOx(5\%)-MWCNT) displayed balanced active Pt area and excellent oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) activities. Rotating Disk Electrode (ROE) system was extensively utilized to understand the ORR kinetics and the favorable role of MoOx as the promoter in the reaction. The kinetic current (j(k)) measured at 0.02 V vs. Hg/Hg2SO4 electrode from the Koutecky-Levich plots was 9 times higher and the apparent activation energy during single cell evaluation was 27 kJ/mol lower for the MoOx promoted system, compared to the system without the additive. A higher operating temperature significantly favored the cell performance by a combined effect of enhancement in proton conductivity of the PBI membrane and possible kinetic benefit by the well postulated oxygen spill over effect by the MoOx type systems in some combinations involving such systems. (C) 2010 Elsevier Ltd. All rights reserved.

}, keywords = {Methanol oxidation reaction, MWCNT, oxygen reduction reaction, PBI membrane, PEMFC}, issn = {0013-4686}, doi = {10.1016/j.electacta.2010.01.012}, author = {Vellacheri, Ranjith and Unni, SreeKuttan M. and Nahire, Sandip and Kharul, Ulhas K. and Kurungot, Sreekumar} } @article { ISI:000290732000044, title = {Enhanced electrocatalytic performance of functionalized carbon nanotube electrodes for oxygen reduction in proton exchange membrane fuel cells}, journal = {Physical Chemistry Chemical Physics}, volume = {13}, number = {21}, year = {2011}, month = {APR}, pages = {10312-10317}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Although nitrogen doped CNTs (N-CNTs) are considered as a promising alternative to platinized carbon for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs), the origin of the enhanced ORR activity with N-CNTs is not clear at present. Among several plausible reasons, the exposure of edge plane and creation of impurity band/surface states near the Fermi level are considered as major causes behind the catalytic activity. However, CNTs without nitrogen doping are not known to catalyze the ORR. In this work, we study the ORR activity of functionalized carbon nanotubes with different functional groups, such as sulfonic acid and phosphonic acid, in order to understand the role of surface functionalities in catalyzing the reaction. Functionalized CNTs show significantly enhanced activity towards the ORR, while CNTs without such surface functional groups do not reveal any such special ORR activity. Linear sweep voltammetry experiments with different rotation rates show diffusion controlled limiting current values for functionalized CNTs, and the {\textquoteleft}n{\textquoteright} values derived from Koutecky-Levich plots are 3.3 and 1.7 for S-MWCNTs and P-MWCNTs, respectively. This work demonstrates the ORR activity of functionalized MWCNTs, which opens up new strategies for electrocatalyst design in PEMFCs.

}, issn = {1463-9076}, doi = {10.1039/c0cp02853c}, author = {Kannan, Ramaiyan and Bipinlal, Unni and Kurungot, Sreekumar and Pillai, Vijayamohanan K.} } @article { ISI:000288386600076, title = {Ex-situ dispersion of core-shell nanoparticles of Cu-Pt on an in situ modified carbon surface and their enhanced electrocatalytic activities}, journal = {Chemical Communications}, volume = {47}, number = {13}, year = {2011}, month = {FEB}, pages = {3951-3953}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Direct dispersion of core-shell nanoparticles on a carbon support (Cu@ Pt/C) has been achieved while retaining the essential core-shell features of the nanoparticles by adopting an in situ surface modification-cum-anchoring strategy.

}, issn = {1359-7345}, doi = {10.1039/c0cc05645f}, author = {Dhavale, Vishal M. and Unni, SreeKuttan M. and Kagalwala, Husain N. and Pillai, Vijayamohanan K. and Kurungot, Sreekumar} } @article { ISI:000287530700045, title = {Facile construction of non-precious iron nitride-doped carbon nanofibers as cathode electrocatalysts for proton exchange membrane fuel cells}, journal = {Chemical Communications}, volume = {47}, number = {10}, year = {2011}, month = {JAN}, pages = {2910-2912}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

We demonstrate a facile construction of iron nitride-doped carbon nanofiber by effectively utilizing the existing slit pores and rough edges along the inner wall of the substrate as originated by virtue of its cup-stack structure for effectively increasing the number of active sites and consequently the oxygen reduction activity.

}, issn = {1359-7345}, doi = {10.1039/c0cc04605a}, author = {Palaniselvam, Thangavelu and Kannan, Ramaiyan and Kurungot, Sreekumar} } @article { ISI:000297265800023, title = {Highly exposed and activity modulated sandwich type Pt thin layer catalyst with enhanced utilization}, journal = {Journal of Materials Chemistry}, volume = {21}, number = {47}, year = {2011}, month = {OCT}, pages = {19039-19048}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A Pt thin layer catalyst supported on an in situ prepared {\textquoteleft}RuO(2)-carbon-RuO(2){\textquoteright} sandwich type hybrid support is presented. This is achieved by the extensive functionalization of a hollow carbon nanofiber support to introduce oxygen containing functional groups (FCNF) with the specific aim to accomplish the exclusive adsorption of Ru ions along its inner cavity and outer surfaces. Preferential adsorption of Ru ions from a mixture of Pt and Ru with sufficient time for adsorption and reorganization of ions on the carbon nanofiber surface leads to the in situ renovation of FCNFs to form a hybrid {\textquoteleft}RuO(2)-carbon-RuO(2){\textquoteright} sandwich type support followed by Pt nanoparticle decoration. While the selective exposure of Pt on the hybrid support surface is confirmed from the HRTEM analysis, the electronic changes effected in the CNF support are evident from the XPS and XRD analysis. Finally, the potential benefit of such a design is also demonstrated using electrochemical studies, where the three-fold increase in the electrochemically active surface area from cyclic voltammetric analysis, a four-fold improvement in the limiting current density coupled with a 80 mV gain in onset potential from rotating disc electrode studies for the oxygen reduction reaction, and a drastic reduction in the CO poisoning for methanol oxidation reaction underlines the superb performance of this material. Such an exceptionally high performance can be attributed to the strong electronic perturbations occurring in the Pt and the FCNF support due to the presence of a continuous RuO(2) layer in between. Such a high aspect ratio core-shell type design with an unusual enhancement in the Pt utilization establishes the roles of both the hybrid support and active catalyst to address the future challenges in the area of utilization improvement.

}, issn = {0959-9428}, doi = {10.1039/c1jm11588j}, author = {Balan, Beena K. and Kurungot, Sreekumar} } @article { ISI:000290167200026, title = {Improved performance of phosphonated carbon nanotube-polybenzimidazole composite membranes in proton exchange membrane fuel cells}, journal = {Journal of Materials Chemistry}, volume = {21}, number = {20}, year = {2011}, month = {APR}, pages = {7223-7231}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Development of thermally stable polymer electrolyte membranes with higher proton conductivity as well as mechanical stability is a key challenge in commercializing PEM fuel cells operating above 100 degrees C. Polybenzimidazole membranes are one of the promising candidates in this category although with limited mechanical stability and moderate proton conductivity. Here the incorporation of functionalized MWCNT is shown to increase both these key parameters of the polybenzimidazole membranes. Further, formation of a domain like structure after the incorporation of phosphonated MWCNTs (P-MWCNTs) in phosphoric acid doped polybenzimidazole membranes is demonstrated. The enhanced performance has been attributed to the formation of proton conducting networks that formed along the sidewalls of P-MWCNTs with a domain size of 17 nm as estimated from the small angle X-ray scattering measurements. Membrane electrode assembly (MEA) impedance measurements further reveal that the activation energy of oxygen reduction reaction (ORR) reduced for the composite membranes with enhanced proton conductivity. In addition, the mechanical strength measurements reveal a significant improvement in the yield strength and ultimate strength. Also, the mechanical strength of the composite membrane has been increased significantly as indicated by the improvement in the ultimate strength from 65 MPa to 100 MPa for the pristine and composite membranes, respectively. The optimum loading of P-MWCNTs is found to be 1\% as inferred from the polarization measurements carried out using pure hydrogen and oxygen. Thus, this study provides a unique opportunity to tune the properties of polymer electrolytes to prepare application oriented hybrid membranes using CNTs with tailor-made functional groups.

}, issn = {0959-9428}, doi = {10.1039/c0jm04265j}, author = {Kannan, Ramaiyan and Kagalwala, Husain N. and Chaudhari, Harshal D. and Kharul, Ulhas K. and Kurungot, Sreekumar and Pillai, Vijayamohanan K.} } @article { ISI:000311056800010, title = {3D Hexaporous carbon assembled from single-layer graphene as high performance supercapacitor}, journal = {Chemsuschem}, volume = {5}, number = {11}, year = {2012}, month = {OCT}, pages = {2159-2164}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, keywords = {Electrochemistry, Energy storage, graphene, porous materials, Supercapacitors}, issn = {1864-5631}, doi = {10.1002/cssc.201200421}, author = {Yadav, Prasad and Banerjee, Abhik and Unni, Sreekuttan and Jog, Jyoti Prakash and Kurungot, Sreekumar and Ogale, Satishchandra} } @article { ISI:000306503200003, title = {Activity modulated low platium content oxygen reduction electrocatalysts prepared by inducing nano-order dislocations on carbon nanofiber through N-2-doping}, journal = {Journal of Physical Chemistry C}, volume = {116}, number = {28}, year = {2012}, month = {JUL}, pages = {14754-14763}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

We demonstrate how surface unsaturation developed during small order buckling of graphene interlayer upon doping iron nitride (i.e., FeNx) moieties in carbon nanofiber can be utilized as a very efficient mode of surface activation to establish fine distribution of Pt nanoparticles with 10 wt \%. The surface dislocations have been effectively modulating the oxygen reduction characteristics of Pt through synergistic effects of the interacting species. The simultaneous enhancement of dispersion of Pt and oxygen reduction reaction (ORR) activity with a low weight percentage of dispersed Pt has been attained by FeNx doping, which increases the density of the active sites owing to the formation of fine and abundant delaminated regions on the CNF surface. HR-TEM images clearly depict the fine distribution of Pt nanoparticles on the delaminated regions of FeNxCNF. The stable incorporation of Pt on nitrogen doped active sites has been further confirmed by observing the formation of Pt-N peak at 391.5 eV using XPS analysis. The fine distribution of Pt nanoparticles along the abundant nanopockets between the buckled graphene layers helped the system to attain significantly high electrochemically active surface area of Pt as evident from the cyclic voltammetric studies. The mass activity of PtFeNxCNF at 0.9 V vs RHE is 4.9 mA mgPt(-1) which is two times higher than that of E-TEK. The superior catalytic activity (exchange current density (i(0)) at 0.8 V is 2.61X 10(-6)) could be further confirmed by single cell evaluation of the membrane electrode assembly (MEA) of polymer electrolyte fuel cell (PEFC), where the cathode electrode was fabricated from this new catalyst.

}, issn = {1932-7447}, doi = {10.1021/jp300881p}, author = {Palaniselvam, Thangavelu and Irshad, Ahamed and Unni, Bipinlal and Kurungot, Sreekumar} } @article { ISI:000311522500012, title = {Efficient oxygen reduction electrocatalyst from graphene by simultaneously generating pores and nitrogen doped active sites}, journal = {Journal of Materials Chemistry}, volume = {22}, number = {45}, year = {2012}, month = {DEC}, pages = {23799-23805}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A simple way to simultaneously create pores and nitrogen doped active sites on graphene for the electrochemical oxygen reduction reaction (ORR) is developed. The key aspect of the process is the in-situ generation of Fe2O3 nanoparticles and their concomitant dispersion on graphene by pyrolyzing graphene oxide (GO) with the iron phenanthroline complex. Thus the deposited Fe2O3 nanoparticles act as the seeds for pore generation by etching the carbon layer along the graphene-Fe2O3 interface. Detection of the presence of Fe3C along with Fe2O3 confirms carbon spill-over from graphene as a plausible step involved in the pore engraving process. Since the process offers a good control on the size and dispersion of the Fe2O3 nanoparticles, the pore size and distribution also could be managed very effectively in this process. As the phenanthroline complex decomposes and gives Fe2O3 nanoparticles and subsequently the pores on graphene, the unsaturated carbons along the pore openings simultaneously capture nitrogen of the phenanthroline complex and provide very efficient active sites for ORR under alkaline conditions. The degree of nitrogen doping and hence the ORR activity could be further improved by subjecting the porous material for a second round of nitrogen doping using iron-free phenanthroline. This porous graphene enriched with the N-doped active sites effectively reduces oxygen molecule through a 3e(-) pathway, suggesting a preferential shift towards the more favourable 4e(-) route compared to the 2e(-) reaction as reported for many N-doped carbon nano-morphologies. The 90 mV onset potential difference for oxygen reduction as compared to the state-of-the art 20 wt\% Pt/C catalyst is significantly low compared to the overpotentials in the range of 120-200 mV reported in the literature for few N-doped graphenes.

}, issn = {0959-9428}, doi = {10.1039/c2jm35128e}, author = {Palaniselvam, Thangavelu and Aiyappa, Harshitha Barike and Kurungot, Sreekumar} } @article { ISI:000310934400028, title = {Graphene enriched with pyrrolic coordination of the doped nitrogen as an efficient metal-free electrocatalyst for oxygen reduction}, journal = {Journal of Materials Chemistry}, volume = {22}, number = {44}, year = {2012}, month = {NOV}, pages = {23506-23513}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

We report an efficient template-free synthetic route for the preparation of mesoporous nitrogen-doped graphene (NGE) containing a high weight percentage of pyrrolic nitrogen, good specific surface area and comparable electrochemical oxygen reduction activity as that of the state-of-the-art 40 wt\% Pt/C catalyst. The desired coordination of nitrogen in the carbon framework of graphene has been conceived by a mutually assisted redox reaction between graphene oxide (GO) and pyrrole, followed by thermal treatment at elevated temperatures. NGE exhibits a high surface area of 528 m(2) g(-1) and a pore diameter of similar to 3 to 7 nm. The heat treatment temperature plays a pivotal role in establishing the desired pyrrolic coordination of nitrogen in graphene for the electrochemical oxygen reduction reaction. The NGE sample obtained after heat treatment at 1000 degrees C (NGE-1000) has 53\% pyrrolic nitrogen content compared to the similar samples prepared by treating at low temperatures. Most importantly, NGE-1000 has displayed a significantly low overpotential for oxygen reduction with the onset potential very closely matching that of the commercial 40 wt\% Pt/C. It is noteworthy that the reaction involves the desired 4 electron transfer as observed in the case of the Pt based electrocatalysts, leading to a significantly high kinetic current density of 6 mA cm(-2) at -0.2 V. Moreover, the fuel tolerance and durability under the electrochemical environment of the NGE catalyst is found to be superior to the Pt/C catalyst.

}, issn = {0959-9428}, doi = {10.1039/c2jm35547g}, author = {Unni, SreeKuttan M. and Devulapally, Saikrishna and Karjule, Neeta and Kurungot, Sreekumar} } @article { ISI:000299292600030, title = {Hydrous RuO2-carbon nanofiber electrodes with high mass and electrode-specific capacitance for efficient energy storage}, journal = {Nanoscale}, volume = {4}, number = {3}, year = {2012}, month = {DEC}, pages = {890-896}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

We demonstrate a new strategy for the fabrication of supercapacitor electrodes possessing high mass and area-specific capacitance for efficient charge storage, which can be extremely useful for the development of light, compact and high performance supercapacitors for a variety of high power demanding applications. High mass and electrode area specific capacitances were attained by using Hydrous Ruthenium Oxide (HRO)-Carbon Nanofiber (CNF) hybrid electrodes prepared by the deposition of HRO (similar to 31\% Ru content) on both the outer and inner surfaces of a cylindrical hollow CNF having open tips. Electrochemical studies of the uniformly deposited HRO nanoparticles on the CNF surface showed a mass specific capacitance of 645 F g(-1) and an electrode specific capacitance of 1.29 F cm(-2) with a HRO-CNF material loading of 2 mg cm(-2) in the supercapacitor electrodes. The mass specific capacitance of pure HRO is 301 F g(-1), whereas the mass specific capacitance of HRO in the HRO-CNF electrode is similar to 1300 F g(-1), which is very close to the theoretical capacitance of HRO. This enhanced charge storage ability, high rate capability, better cyclic stability and low ESR of the HRO-CNF will be useful for the development of high performance supercapacitors.

}, issn = {2040-3364}, doi = {10.1039/c2nr11479h}, author = {Vellacheri, Ranjith and Pillai, Vijayamohanan K. and Kurungot, Sreekumar} } @article { ISI:000299290200019, title = {One-dimensional confinement of a nanosized metal organic framework in carbon nanofibers for improved gas adsorption}, journal = {Chemical Communications}, volume = {48}, number = {14}, year = {2012}, month = {DEC}, pages = {2009-2011}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The loading of a Zn-terephthalate based MOF in the inner cavity as well as on the outer walls of a hollow carbon nanofiber (CNF) creates MOF@CNF hybrids. This hybrid {\textquoteleft}{\textquoteleft}MOF@CNF{\textquoteright}{\textquoteright} displayed improved thermal stability as well as gas adsorption compared to the individual counterparts.

}, issn = {1359-7345}, doi = {10.1039/c2cc16877d}, author = {Pachfule, Pradip and Balan, Beena K. and Kurungot, Sreekumar and Banerjee, Rahul} } @article { ISI:000310934400049, title = {Polybenzimidazole mediated N-doping along the inner and outer surfaces of a carbon nanofiber and its oxygen reduction properties}, journal = {Journal of Materials Chemistry}, volume = {22}, number = {44}, year = {2012}, month = {NOV}, pages = {23668-23679}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Nitrogen-doped (N-doped) hollow carbon nanofiber (CNF) was synthesized by incorporating a nitrogen containing polymer precursor, polybenzimidazole (PBI-BuI), in the inner cavity as well as on the outer walls of the CNF, followed by a high temperature treatment. PBI-BuI incorporation along the inner and outer surface of the CNF was accomplished by synthesizing a low molecular weight polymer by tuning the synthetic parameters. The solution concentration of the PBI-BuI is also varied to facilitate its entry into the CNF by capillary action. The high temperature treatment (700-1000 degrees C) of the resulting CNF-PBI material decomposes the polymer and induces N-doping along the inner and outer surfaces of the CNF. The initial PBI-BuI content and the annealing temperature are also systematically varied to choose the right combination of starting precursors and heat-treatment conditions. Detailed X-ray photoelectron spectroscopy analysis of the samples shows that pyridinic-type nitrogen is the major component in all the samples. Electrochemical characterizations of this material using cyclic voltammetry, rotating disc electrode studies and durability analysis demonstrated that this material can act as a metal-free oxygen reduction electrocatalyst with improved oxygen reduction kinetics and stability. It is also revealed that the onset potential, limiting current density, number of transferred electrons, etc. have a strong dependence on the annealing temperature.

}, issn = {0959-9428}, doi = {10.1039/c2jm35033e}, author = {Balan, Beena K. and Manissery, Aiswarya Padinhare and Chaudhari, Harshal D. and Kharul, Ulhas K. and Kurungot, Sreekumar} } @article { ISI:000308778000025, title = {Tuning the functionality of a carbon nanofiber-Pt-RuO2 system from charge storage to electrocatalysis}, journal = {Inorganic Chemistry}, volume = {51}, number = {18}, year = {2012}, month = {SEP}, pages = {9766-9774}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Chemical-functionalization-induced switching in the property of a hybrid system composed of a hollow carbon nanofiber (CNF) and Pt and RuO2 nanoparticles from charge storage to electrocatalysis is presented. The results of this study show how important it is to have a clear understanding of the nature of surface functionalities in the processes involving dispersion of more than one component on various substrates including carbon nanomorphologies. When pristine CNF is used to decorate Pt and RuO2 nanoparticles, random dispersion occurs on the CNF surface (C-PtRuO2). This results in mainly phase-separated nanoparticles rich in RuO2 characteristics. In contrast to this, upon moving from the pristine CNF to those activated by a simple H2O2 treatment to create oxygen-containing surface functional groups, a material rich in Pt features on the surface is obtained (F-PtRuO2). This is achieved because of the preferential adsorption of RuO2 by the functionalized surface of CNF. A better affinity of the oxygen-containing functional groups on CNF toward RuO2 mobilizes relatively faster adsorption of this moiety, leading to a well-controlled segregation of Pt nanoparticles toward the surface. Further reorganization of Pt nanoparticles leads to the formation of a Pt nanosheet structure on the surface. The electrochemical properties of these materials are initially evaluated using cyclic voltammetric analysis. The cyclic voltammetric results indicate that C-PtRuO2 shows a charge storage property, a typical characteristic of hydrous RuO2, whereas F-PtRuO2 shows an oxygen reduction property, which is the characteristic feature of Pt. This clear switch in the behavior from charge storage to electrocatalysis is further confirmed by galvanostatic charge discharge and rotating-disk-electrode studies.

}, issn = {0020-1669}, doi = {10.1021/ic301147s}, author = {Balan, Beena K. and Kurungot, Sreekumar} } @article { ISI:000302336700011, title = {Tuning the performance of low-Pt polymer electrolyte membrane fuel cell electrodes derived from Fe2O3@Pt/C core-shell catalyst prepared by an in situ anchoring strategy}, journal = {Journal of Physical Chemistry C}, volume = {116}, number = {13}, year = {2012}, month = {APR}, pages = {7318-7326}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A low-Pt electrode with high performance and durability characteristic has been realized for polymer electrolyte membrane fuel cell applications from a carbon-supported Fe2O3@Pt core-shell catalyst prepared by a process involving in situ surface modification-cum-anchoring strategy. The process is based on an in-house-developed methodology for generating and interlocking the core-shell nanoparticles on the surface of the carbon substrate, which undergoes functionalization in the reaction medium itself by the intervention of the reducing agent employed in the reaction. Ascorbic acid, which was used as the reducing agent in the process, played a crucial role by making use of its multifunctional activities as reducing agent, stabilizing agent, as well as capping agent in addition to its efficiency in functionalizing the carbon surface during the course of the reaction. The formation of core-shell nanostructures could be confirmed by XRD, HR-TEM, and cyclic voltammetric analysis. The oxygen reduction property and the performance during the single cell evaluations were found to be strongly influenced by the thickness of the catalyst layer owing to the ohmic contribution from the higher mass fraction of the less conductive Fe2O3 core. However, when the thickness of the catalyst layer was kept within the threshold level, Fe2O3@Pt catalyst clearly outperforms the commercial Pt/C catalyst. This benefit of the core-shell catalyst enabled it to display a maximum power density of 900 mW/cm(2) with a significantly low cathode Pt loading of 0.05 mg/cm(2). An accelerated durability assessment of the membrane electrode assembly for 10 h gave consistent performance characteristics. The study gave convincing evidence on the feasibility of using the electrodes derived from the core-shell catalyst prepared by the in situ anchoring strategy for developing cost competitive systems and miniature cells for niche applications.

}, issn = {1932-7447}, doi = {10.1021/jp300628j}, author = {Dhavale, Vishal M. and Kurungot, Sreekumar} } @article { ISI:000321203900073, title = {1-Dimensional confinement of porous polyethylenedioxythiophene using carbon nanofibers as a solid template: an efficient charge storage material with improved capacitance retention and cycle stability}, journal = {RSC Advances}, volume = {3}, number = {29}, year = {2013}, month = {APR}, pages = {11877-11887}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Here, we report a highly conducting porous 1-dimensionally (1-D) confined nano hybrid of polyethylenedioxythiophene (PEDOT) using a cup-stacked hollow carbon nanofiber (CNF) as a solid template for potential charge storage applications. The unique features of the nano confinement involve significantly high porosity and conductivity with the establishment of the 1-D architecture. Since the tubular morphology of the CNF with its open tips provides facile routes for the electrolyte, the overall utilization of the active surface and conductivity increases the charge storage properties of PEDOT in the hybrid. The approach helped in achieving a high specific capacitance of 177 F g(-1) for 40\% PEDOT-CNF at a scan rate of 50 mV s(-1) and in retaining 130 F g(-1) even at 3000 mV s(-1) compared to 76 and 30 F g(-1) respectively given by pure PEDOT in 0.5 M H2SO4. The hybrid CP-40 shows a very high power density of 51 kW kg(-1) with an energy density of 4.7 Wh kg(-1). High capacitance retention is supported by the low charge transfer resistance and very low time constant (less than 0.5 s) values for the hybrid using impedance analysis. Phase angle calculations from a Bode plot also show an ideal capacitive nature with -90 degrees phase difference at 0.1 Hz for the hybrids. Apart from all these, the solid CNF backbone helps the hybrid material to display excellent cycle stability with \>98\% retention in capacitance over 4500 charge-discharge cycles compared to pristine PEDOT at a current density of 2 A g(-1).

}, issn = {2046-2069}, doi = {10.1039/c3ra40853a}, author = {Anothumakkool, Bihag and Bhange, Siddheshwar N. and Unni, SreeKuttan M. and Kurungot, Sreekumar} } @article { ISI:000317929800033, title = {3-Dimensionally self-assembled single crystalline platinum nanostructures on few-layer graphene as an efficient oxygen reduction electrocatalyst}, journal = {RSC Advances}, volume = {3}, number = {19}, year = {2013}, month = {FEB}, pages = {6913-6921}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Here, we report for the first time the synthesis of a 3-D self-assembled single crystalline platinum nanostructure directly on the graphene surface (PtNAGE) without using any harmful structural directing agents. A slow reduction method is used to prepare the desired platinum morphology. Initial formation of platinum nanoparticles and their homogenous dispersion on the surface of graphene have been observed 10 h after the commencement of the reduction using formic acid as the reducing agent. From these initially deposited seed particles, the growth starts on the {111} facets along the \< 111 \> direction and the nanostructure formation is completed within 72 h of the commencement of the reaction. The individual assembly has a diameter of similar to 80 nm. PtNAGE shows superior electrocatalytic activity towards oxygen reduction compared to graphene supported platinum (PtGE) and commercial carbon supported platinum (PtC) catalysts. PtNAGE is less vulnerable to strong hydroxyl adsorption compared to PtC and PtGE. Specific activity and mass activity of the catalyst are high compared to PtC by a factor of 6.50 and 1.80, respectively, and 4.00 and 3.05, respectively, compared to PtGE. The limiting current density of PtNAGE is 1.28 and 1.20 times higher than PtGE and PtC, respectively. Kinetic analysis of PtNAGE shows that the oxygen reduction reaction follows first order kinetics involving a four electron transfer mechanism with the direct formation of water. In addition to this, it has been observed that PtNAGE also prevents surface area degradation better than the commercial platinised carbon under potential induced conditions.

}, issn = {2046-2069}, doi = {10.1039/c3ra23112g}, author = {Unni, SreeKuttan M. and Pillai, Vijayamohanan K. and Kurungot, Sreekumar} } @article { ISI:000313812400048, title = {Carbon nanofiber-RuO2-poly(benzimidazole) ternary hybrids for improved supercapacitor performance}, journal = {RSC Advances}, volume = {3}, number = {7}, year = {2013}, month = {DEC}, pages = {2428-2436}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Carbon nanofiber-RuO2-poly(benzimidazole) ternary hybrid electrode material which integrates dual wall decoration and interfacial area tuning for supercapacitor applications has been devised based on a simple approach. This is achieved by decorating RuO2 nanoparticles of size ca. 2-3 nm along the inner and outer walls of a hollow carbon nanofiber (CNF) support (F-20RuO(2)). In the next step, a proton conducting polymer, phosphoric acid doped polybenzimidazole (PBI-BuI), interface is created along the inner and outer surfaces of this material. A 103\% increase in the specific capacitance is obtained for RuO2-PBI hybrid material as compared to that of F-20RuO(2) at the optimum level of the polymer wrapping. Apart from the high specific capacitance, the RuO2-PBI hybrid materials exhibit enhanced rate capability and excellent electrochemical stability of 98\% retention in the capacitance. Such a remarkably high activity can be primarily attributed to the efficient dispersion of active sites achieved by properly utilizing inner and outer surfaces of CNF. Apart from this, the facile routes for ion transport created as a result of PBI incorporation coupled with excellent interfacial contact between the RuO2 and the electrolyte resulting in the improved utilization of the active material also contribute to the improved activity. In addition to this, the synergistic effects of pseudocapacitive contribution from both the PBI-BuI and RuO2 also contribute to the redefined performance characteristics.

}, issn = {2046-2069}, doi = {10.1039/c2ra22776b}, author = {Balan, Beena K. and Chaudhari, Harshal D. and Kharul, Ulhas K. and Kurungot, Sreekumar} } @article { ISI:000329137400081, title = {Design of a high performance thin all-solid-state supercapacitor mimicking the active interface of its liquid-state counterpart}, journal = {ACS Applied Materials \& Interfaces}, volume = {5}, number = {24}, year = {2013}, month = {DEC}, pages = {13397-13404}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Here we report an all-solid-state supercapacitor (ASSP) which closely mimics the electrode-electrolyte interface of its liquid-state counterpart by impregnating polyaniline (PANO-coated carbon paper with polyvinyl alcohol-H2SO4 (PVA-H2SO4) gel/plasticized polymer electrolyte. The well penetrated PVA-H2SO4 network along the porous carbon matrix essentially enhanced the electrode-electrolyte interface of the resulting device with a very low equivalent series resistance (ESR) of 1 Omega/cm(2) and established an interfacial structure very similar to a liquid electrolyte. The designed interface of the device was confirmed by cross-sectional elemental mapping and scanning electron microscopy (SEM) images. The PANI in the device displayed a specific capacitance of 647 F/g with an areal capacitance of 1 F/cm(2) at 0.5 A/g and a capacitance retention of 62\% at 20 A/g. The above values are the highest among those reported for any solid-state-supercapacitor. The whole device, including the electrolyte, shows a capacitance of 12 F/g with a significantly low leakage current of 16 mu A(2). Apart from this, the device showed excellent stability for 10000 cycles with a coulombic efficiency of 100\%. Energy density of the PANI in the device is 14.3 Wh/kg.

}, keywords = {all-solid-state, cyclic voltametry, impedance analysis, polyaniline, polyvinyl alcohol, supercapacitor}, issn = {1944-8244}, doi = {10.1021/am404320e}, author = {Anothumakkool, Bihag and Torris, Arun A. T. and Bhange, Siddheshwar N. and Unni, SreeKuttan M. and Badiger, Manohar V. and Kurungot, Sreekumar} } @article { ISI:000315720000020, title = {Effect of the viscosity of poly(benzimidazole) on the performance of a multifunctional electrocatalyst with an ideal interfacial structure}, journal = {Journal of Materials Chemistry A}, volume = {1}, number = {13}, year = {2013}, month = {JAN}, pages = {4265-4276}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A novel electrocatalyst system with unique multifunctional characteristics, originated by the presence of a proton conducting polybenzimidazole (PBI-BuI) bound layer and electron conducting hollow carbon nanofibers (CNF) with catalytically active Pt nanoparticles, has been devised based on a simple strategy. This was achieved by decorating Pt nanoparticles along the inner cavity, as well as on the outer walls of the hollow CNF support (F-Pt). In a further extension, a low molecular weight PBI, synthesized by optimizing the experimental parameters, was incorporated into the inner cavity and along the outer surfaces of F-Pt. Excellent dispersion of the Pt nanoparticles was achieved by properly utilizing the available carbon surface results in improved electrocatalytic activity, while the CNF backbone ensures high electron conductivity as well. The polymer binder coverage formed along the inner and outer wall surfaces provides an efficient triple phase boundary (TPB) around the Pt nanoparticles to facilitate the electrode reactions. The amount and the viscosity of the PBI-BuI in the electrode material were systematically varied to study the influence on the electrochemical performance. Transmission electron microscopy analysis confirms PBI insertion into the tubular cavity of CNF. Pore size distribution analysis implies that both the viscosity and the amount of PBI-BuI have a pivotal role in defining the microstructure of the electrode. Electrochemical studies using cyclic voltammetry (CV) and rotating disc electrode (RDE) reveal the exceptionally high activity of this hybrid material with an improved electrochemically active area. The significant improvement for the oxygen reduction reaction is further confirmed by the single cell analysis also. The high power density displayed by the PBI-BuI based system, as compared to the Nafion based system, validates the conceptualization of the well controlled triple-phase boundary in the system. These results demonstrate that PBI-BuI has a constructive effect in tuning the electrochemical activity at an optimum amount and at a favourable viscosity of the proton conducting polymer.

}, issn = {2050-7488}, doi = {10.1039/c3ta00165b}, author = {Balan, Beena K. and Unni, Bipinlal and Chaudhari, Harshal D. and Kharul, Ulhas K. and Kurungot, Sreekumar} } @article { ISI:000326300200011, title = {Porous carbons from nonporous MOFs: influence of ligand characteristics on intrinsic properties of end carbon}, journal = {Crystal Growth \& Design}, volume = {13}, number = {10}, year = {2013}, month = {OCT}, pages = {4195-4199}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Synthesis of porous carbons on direct carbonization of nonporous Zn-based MOFs has been achieved without using any additional carbon precursor. The effect of ligand nature on the resulting carbon porosity has been studied systematically using the MOFs synthesized from rigid and flexible ligands. The linear relations between Zn/C ratio of the MOF versus surface area of the resulting carbon, micro-porosity versus H-2 uptake achieved in these carbons, and surface area versus specific capacitance of the end carbons have been verified from the gas adsorption, molecular composition, and electrochemical studies, respectively. Cyclic voltammetry and charge-discharge cycling have been carried out to study the capacitive behavior of the carbons. The interdependence of capacitive behavior on the surface area has been analyzed using data derived from N-2 adsorption isotherms and charge-discharge curves. Among the carbons synthesized, C-MOF-2 shows maximal surface area of 1378 m(2)/g with a specific capacitance of 170 F/g at 1 A/g.

}, issn = {1528-7483}, doi = {10.1021/cg401122u}, author = {Aiyappa, Harshitha Barike and Pachfule, Pradip and Banerjee, Rahul and Kurungot, Sreekumar} } @article { ISI:000313263300022, title = {Porous-organic-framework-templated nitrogen-rich porous carbon as a more proficient electrocatalyst than Pt/C for the electrochemical reduction of oxygen}, journal = {Chemistry-A European Journal}, volume = {19}, number = {3}, year = {2013}, month = {JAN}, pages = {974-980}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

Porous nitrogen-rich carbon (POF-C-1000) that was synthesized by using a porous organic framework (POF) as a self-sacrificing host template in a nanocasting process possessed a high degree of graphitization in an ordered structural arrangement with large domains and well-ordered arrays of carbon sheets. POF-C-1000 exhibits favorable electrocatalytic activity for the oxygen-reduction reaction (ORR) with a clear positive shift of about 40 mV in the onset potential compared to that of a traditional, commercially available Pt/C catalyst. In addition, irrespective of its moderate surface area (785 m2?g-1), POF-C-1000 showed a reasonable H2 adsorption of 1.6 wt?\% (77 K) and a CO2 uptake of 3.5 mmol?g-1 (273 K).

}, keywords = {Adsorption, Electrochemistry, fuel cells, oxygen-reduction reaction, porous organic frameworks}, issn = {0947-6539}, doi = {10.1002/chem.201202940}, author = {Pachfule, Pradip and Dhavale, Vishal M. and Kandambeth, Sharath and Kurungot, Sreekumar and Banerjee, Rahul} } @article { ISI:000325548600016, title = {Redox-mediated synthesis of functionalised graphene: a strategy towards 2D multifunctional electrocatalysts for energy conversion applications}, journal = {ChemPlusChem}, volume = {78}, number = {10}, year = {2013}, month = {OCT}, pages = {1296-1303}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

A simple, one-step synthetic route for developing a two-dimensional multifunctional electrocatalyst is reported, by the functionalisation of graphene using oxidised ethylenedioxythiophene (O-EDOT). The mutually assisted redox reaction between graphene oxide (GO) and EDOT facilitates the reduction of GO to graphene with a concomitant deposition of O-EDOT on the surface of the graphene. The oxidised surface of GO catalyses the reaction without using an added reducing agent, so a controlled and uniform deposition of O-EDOT is ensured on the surface of graphene, which essentially prevents the restacking of the layers. UV/Visible, IR, Raman and X-ray photoelectron spectroscopy give valid evidence for the reduction and functionalisation of graphene sheets. The functional groups present on the surface of graphene are found to tune the physical and chemical properties of graphene. Consequently, the functionalised material displays enhanced electrocatalytic activity for the reduction of oxygen to water and I3- to I- relative to pristine graphene. These distinct property characteristics make the material a versatile cathode electrocatalyst for both alkaline anion-exchange membrane fuel cells and dye-sensitised solar cells.

}, keywords = {electrocatalysts, fuel cells, graphene, redox chemistry, solar cells}, issn = {2192-6506}, doi = {10.1002/cplu.201300153}, author = {Unni, SreeKuttan M. and Bhange, Siddheshwar N. and Anothumakkool, Bihag and Kurungot, Sreekumar} } @article { ISI:000325849000034, title = {Zeolitic imidazolate framework (ZIF)-derived, hollow-core, nitrogen-doped carbon nanostructures for oxygen-reduction reactions in PEFCs}, journal = {Chemistry-A European Journal}, volume = {19}, number = {28}, year = {2013}, month = {JUL}, pages = {9335-9342}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

The facile synthesis of a porous carbon material that is doped with iron-coordinated nitrogen active sites (FeNC-70) is demonstrated by following an inexpensive synthetic pathway with a zeolitic imidazolate framework (ZIF-70) as a template. To emphasize the possibility of tuning the porosity and surface area of the resulting carbon materials based on the structure of the parent ZIF, two other ZIFs, that is, ZIF-68 and ZIF-69, are also synthesized. The resulting active carbon material that is derived from ZIF-70, that is, FeNC-70, exhibits the highest BET surface area of 262m2g-1 compared to the active carbon materials that are derived from ZIF-68 and ZIF-69. The HR-TEM images of FeNC-70 show that the carbon particles have a bimodal structure that is composed of a spherical macroscopic pore (about 200nm) and a mesoporous shell. X-ray photoelectron spectroscopy (XPS) reveals the presence of Fe-N-C moieties, which are the primary active sites for the oxygen-reduction reaction (ORR). Quantitative estimation by using EDAX analysis reveals a nitrogen content of 14.5wt.\%, along with trace amounts of iron (0.1wt.\%), in the active FeNC-70 catalyst. This active porous carbon material, which is enriched with Fe-N-C moieties, reduces the oxygen molecule with an onset potential at 0.80V versus NHE through a pathway that involves 3.3-3.8e- under acidic conditions, which is much closer to the favored 4e- pathway for the ORR. The onset potential of FeNC-70 is significantly higher than those of its counterparts (FeNC-68 and FeNC-69) and of other reported systems. The FeNC-based systems also exhibit much-higher tolerance towards MeOH oxidation and electrochemical stability during an accelerated durability test (ADT). Electrochemical analysis and structural characterizations predict that the active sites for the ORR are most likely to be the insitu generated NFeN2+2/C moieties, which are distributed along the carbon framework.

}, keywords = {Doping, Electrochemistry, metal-organic frameworks, Nanostructures, oxygen-reduction reaction}, issn = {0947-6539}, doi = {10.1002/chem.201300145}, author = {Palaniselvam, Thangavelu and Biswal, Bishnu P. and Banerjee, Rahul and Kurungot, Sreekumar} } @article { ISI:000328955200029, title = {Activated nitrogen doped graphene shell towards electrochemical oxygen reduction reaction by its encapsulation on Au nanoparticle (Au@N-Gr) in water-in-oil {\textquoteleft}{\textquoteleft}nanoreactors{\textquoteright}{\textquoteright}}, journal = {Journal of Materials Chemistry A}, volume = {2}, number = {5}, year = {2014}, month = {NOV}, pages = {1383-1390}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Encapsulation of nitrogen doped graphene on Au nanoparticle (Au@N-Gr) could be accomplished through a water-in-oil emulsion technique, where the emulsion droplets act as {\textquoteleft}nanoreactors{\textquoteright} and the redox reaction inside the droplets results in the formation of core-shell nanoparticles. The encapsulation of N-Gr on a small quantity of Au (N-Gr : Au wt ratio of 90 : 10) made the N-Gr layer more conductive and active towards electrochemical oxygen reduction reaction (ORR). The enhanced conductivity helped the system narrow down the ohmic overpotential, and direct electronic interactions between the Au and Gr layers brought in a favourable positive shift to the onset potential for ORR. Encapsulation has helped N-Gr reduce the overpotential by similar to 121 mV as compared to N-Gr alone. Apart from this, the oxygen reduction kinetics of Au@N-Gr also appeared to be superior to N-Gr and Au nanoparticles as separate entities due to greater involvement of the preferred 4-electron reduction pathway. At -0.3 V (vs. Hg/HgO), the percentage of hydrogen peroxide (H2O2) (a product formed from the undesirable 2-electron reduction pathway) was found to be 16.5\% for Au@Gr, where Au was covered with undoped Gr, which gets reduced to a significantly low level of 6.5\% for Au@N-Gr. Au and N-Gr as separate entities give yield of H2O2 as 52.2 and 47.7\%, respectively. From these, it can be concluded that the coverage of N-Gr on Au helps decrease the yield of H2O2 drastically apart from the benefits of synergistic interactions in reducing both ohmic and activation overpotentials.

}, issn = {2050-7488}, doi = {10.1039/c3ta14005a}, author = {Dhavale, Vishal M. and Gaikwad, Sachin S. and Kurungot, Sreekumar} } @article {43040, title = {All-solid-state-supercapacitor and a process for the fabrication thereof}, number = {PCT/IN2014/000233}, year = {2014}, month = {OCT}, abstract = {

The present invention discloses. all-solid-state supercapacitor (ASSP) with enhanced electrode-electrolyte interface which gives highest very high specific capacitance, areal capacitance and shows very low internal resistance (ESR). The invention particularly discloses the fabrication of all-solid-state supercapacitor by intercalation of solid state polymer electrolyte inside the conducting porous substrate coated with a charge storage electrode material to achieve the desired effect.

}, author = {Kurungot, Sreekumar and Badiger, Manohar V. and Anothumakkool, Bihag and Torris, Arun} } @article { ISI:000345234900039, title = {Covalent organic framework-cadmium sulfide hybrid as a prototype photocatalyst for visible-light-driven hydrogen production}, journal = {Chemistry A-European Journal}, volume = {20}, number = {48}, year = {2014}, month = {NOV}, pages = {15961-15965}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

CdS nanoparticles were deposited on a highly stable, two-dimensional (2D) covalent organic framework (COF) matrix and the hybrid was tested for photocatalytic hydrogen production. The efficiency of CdS-COF hybrid was investigated by varying the COF content. On the introduction of just 1 wt\% of COF, a dramatic tenfold increase in the overall photocatalytic activity of the hybrid was observed. Among the various hybrids synthesized, that with 10 wt\% COF, named CdS-COF (90: 10), was found to exhibit a steep H2 production amounting to 3678 mmolh(-1) g(-1), which is significantly higher than that of bulk CdS particles (124 mmolh(-1)g(-1)). The presence of a p-conjugated backbone, high surface area, and occurrence of abundant 2D hetero-interface highlight the usage of COF as an effective support for stabilizing the generated photoelectrons, thereby resulting in an efficient and high photocatalytic activity.

}, keywords = {charge transfer, covalent organic frameworks, hybrid materials, hydrogen production, Photocatalysis}, issn = {0947-6539}, doi = {10.1002/chem.201403800}, author = {Thote, Jayshri and Aiyappa, Harshitha Barike and Deshpande, Aparna and Diaz, David Diaz and Kurungot, Sreekumar and Banerjee, Rahul} } @article { ISI:000339090400033, title = {Distinctive PdCl2-mediated transformation of Fe-based metallogels into metal-organic frameworks}, journal = {Crystal Growth \& Design}, volume = {14}, number = {7}, year = {2014}, month = {JUL}, pages = {3434-3437}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Simple, efficient conversion of viable Fe3+-based metallogels into Fe-metal-organic frameworks (MOFs) has been achieved by PdCl2-mediated gel degradation. The metallogels and the resulting MOFs have been characterized, and a probable mechanism for the event has been elucidated.

}, issn = {1528-7483}, doi = {10.1021/cg500368q}, author = {Aiyappa, Harshitha Barike and Saha, Subhadeep and Garai, Bikash and Thote, Jayshri and Kurungot, Sreekumar and Banerjee, Rahul} } @article { ISI:000337134500027, title = {Electrochemically grown nanoporous MnO2 nanowalls on a porous carbon substrate with enhanced capacitance through faster ionic and electrical mobility}, journal = {Chemical Communications}, volume = {50}, number = {54}, year = {2014}, month = {APR}, pages = {7188-7190}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

We report the deposition of uniform porous MnO2 nanowalls on a conducting carbon fiber substrate using a simple electrochemical method, which produces ordered nano-channels demarcated by the MnO2 walls for easy ion transport and a continuous electron path created by the carbon backbone. The system achieves a specific capacitance of 1149 F g(-1) and retains 565 F g(-1) even at dragging conditions as high as 100 A g(-1).

}, issn = {1359-7345}, doi = {10.1039/c4cc00927d}, author = {Anothumakkool, Bihag and Kurungot, Sreekumar} } @article { ISI:000336883000054, title = {Electrodeposited polyethylenedioxythiophene with infiltrated gel electrolyte interface: a close contest of an all-solid-state supercapacitor with its liquid-state counterpart}, journal = {Nanoscale}, volume = {6}, number = {11}, year = {2014}, month = {JUN}, pages = {5944-5952}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

We report the design of an all-solid-state supercapacitor, which has charge storage characteristics closely matching that of its liquid-state counterpart even under extreme temperature and humidity conditions. The prototype is made by electro-depositing polyethylenedioxythiophene (PEDOT) onto the individual carbon fibers of a porous carbon substrate followed by intercalating the matrix with polyvinyl alcohol-sulphuric acid (PVA-H2SO4) gel electrolyte. The electrodeposited layer of PEDOT maintained a flower-like growth pattern along the threads of each carbon fiber. This morphology and the alignment of PEDOT led to an enhanced surface area and electrical conductivity, and the pores in the system enabled effective intercalation of the polymer-gel electrolyte. Thus, the established electrode-electrolyte interface nearly mimics that of its counterpart based on the liquid electrolyte. Consequently, the solid device attained very low internal resistance (1.1 Omega cm(-2)) and a high specific capacitance (181 F g(-1)) for PEDOT at a discharge current density of 0.5 A g(-1). Even with a high areal capacitance of 836 mF cm(-2) and volumetric capacitance of 28 F cm(-3), the solid device retained a mass-specific capacitance of 111 F g(-1) for PEDOT. This is in close agreement with the value displayed by the corresponding liquid-state system (112 F g(-1)), which was fabricated by replacing the gel electrolyte with 0.5 M H2SO4. The device also showed excellent charge-discharge stability for 12 000 cycles at 5 A g(-1). The performance of the device was consistent even under wide-ranging humidity (30-80\%) and temperature (-10 to 80 degrees C) conditions. Finally, a device fabricated by increasing the electrode area four times was used to light an LED, which validated the scalability of the process.

}, issn = {2040-3364}, doi = {10.1039/c4nr00659c}, author = {Anothumakkool, Bihag and Torris, Arun A. T. and Bhange, Siddheshwar N. and Badiger, Manohar V. and Kurungot, Sreekumar} } @article { ISI:000340520500055, title = {Enhanced catalytic activity of polyethylenedioxythiophene towards tri-iodide reduction in DSSCs via 1-dimensional alignment using hollow carbon nanofibers}, journal = {Nanoscale}, volume = {6}, number = {17}, year = {2014}, month = {JUL}, pages = {10332-10339}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Here, we report a highly conducting 1-dimensionally (1-D) aligned polyethylenedioxythiophene (PEDOT) along the inner and outer surfaces of a hollow carbon nanofiber (CNF) and its application as a counter electrode in a dye sensitized solar cell (DSSC). The hybrid material (CP-25) displays a conversion efficiency of 7.16\% compared to 7.30\% for the standard Pt counter electrode, 4.48\% for bulk PEDOT and 5.56\% for CNF. The enhanced conversion efficiency of CP-25 is attributed to the accomplishment of high conductivity and surface area of PEDOT through the 1-D alignment compared to its bulk counterpart. Reduced charge transfer resistance and high conductivity of CP-25 could be proven by cyclic voltammetry, impedance analysis and Tafel experiments. Further, through a long-term stability test involving efficiency profiling for 20 days, it is observed that CP-25 possesses excellent durability compared to the bulk PEDOT.

}, issn = {2040-3364}, doi = {10.1039/c4nr00717d}, author = {Anothumakkool, Bihag and Game, Onkar S. and Bhange, Siddheshwar N. and Kumari, Tanya and Ogale, Satishchandra B. and Kurungot, Sreekumar} } @article {46360, title = {From waste paper basket to solid state and Li-HEC ultracapacitor electrodes: a value added journey for shredded office paper}, journal = {Small}, volume = {10}, year = {2014}, month = {NOV}, pages = {4395-4402}, type = {Article}, abstract = {

Hydrothermal processing followed by controlled pyrolysis of used white office paper (a globally collectable shredded paper waste) are performed to obtain high surface area carbon with hierarchical pore size distribution. The BET specific surface area of such carbon is 2341 m 2 g(-1). The interconnected macroporous structure along with the concurrent presence of mesopores and micropores makes the material ideal for ultracapacitor application. Such waste paper derived carbon (WPC) shows remarkable performance in all solid-state supercapacitor fabricated with ionic liquid-polymer gel electrolyte. At room temperature, the material exhibits a power density of 19 000 W kg(-1) with an energy capability of 31 Wh kg(-1). The Li-ion electrochemical capacitor constructed using WPC as cathode also shows an excellent energy storage capacity of 61 Wh kg(-1)

}, issn = {1613-6810}, doi = {10.1002/smll.201401041}, author = {Puthusseri, Dhanya and Aravindan, Vanchiappan and Anothumakkool, Bihag and Kurungot, Sreekumar and Madhavi, Srinivasan and Ogale, Satishchandra} } @article { ISI:000343988200032, title = {Layer-separated distribution of nitrogen doped graphene by wrapping on carbon nitride tetrapods for enhanced oxygen reduction reactions in acidic medium}, journal = {Chemical Communications}, volume = {50}, number = {89}, year = {2014}, month = {SEP}, pages = {13769-13772}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Layer-separated 3D nitrogen doped graphene (NG) with an accessible interstitial surface and modulated activity characteristics for oxygen reduction in acidic medium could be prepared by wrapping NG sheets on in situ generated carbon nitride (CNx) tetrapods.

}, issn = {1359-7345}, doi = {10.1039/c4cc06180b}, author = {Unni, SreeKuttan M. and Illathvalappil, Rajith and Gangadharan, Pranav K. and Bhange, Siddheshwar N. and Kurungot, Sreekumar} } @article { ISI:000333203900024, title = {Nanoporous graphene by quantum dots removal from graphene and its conversion to a potential oxygen reduction electrocatalyst via nitrogen doping}, journal = {Energy \& Environmental Science}, volume = {7}, number = {3}, year = {2014}, month = {MAR}, pages = {1059-1067}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A simple way to produce an efficient metal-free oxygen reduction electrocatalyst from graphene by generating nanopores in the matrix and subsequently establishing nitrogen-doped active sites along the pore openings is demonstrated. Well-structured nanoporous graphene (pGr) and photoluminescent graphene quantum dots (GQDs) could be simultaneously generated by a chemically assisted oxidative treatment of graphene. The process helped to knock out small pieces of Gr through epoxide formation, which subsequently resulted in the generation of GQD and pGr simultaneously. A longer oxidation time increased the quantity of GQDs and also resulted in a higher photoluminescent (PL) quantum yield. The PL quantum yield of GQD formed after 72 h of the oxidative treatment (GQD-72) was 15.8\%, which is greater than the previous reported values. The TEM images showed matching sizes for GQDs and the pores present in pGr, implying that the pores are generated by the removal of GQDs from graphene during the oxidative treatment. Since pore openings are expected to give higher levels of unsaturation and defect sites in the system and are thus being treated as fertile regions for heteroatom doping, pGr-72 was further subjected to nitrogen (NpGr-72). NpGr-72 displayed excellent activity towards the electrochemical oxygen reduction reaction (ORR) compared to nitrogen-doped non-porous graphene (NGr) and many other reported nitrogen-doped carbon materials. A distinct 50 mV gain in the overpotential and 2.5 times increment in the kinetic current density (j(k)) have been achieved in the case of NpGr-72 compared to NGr. Interestingly, unlike NGr, NpGr-72 effectively reduced the oxygen molecule with a greater involvement of the preferred four-electron pathway. Additionally, the overpotential difference of NpGr-72 with respect to 20 wt\% Pt/C is only 60 mV. Additionally, in a single cell evaluation under anion exchange membrane fuel cell (AEMFC) conditions, NpGr-72 exhibited a maximum power density of 27 mW cm(-2), which is significantly higher than the corresponding value of 10 mW cm(-2) obtained for NGr. Thus, the overall enhancement in the performance characteristics of NpGr-72 is attributed to the higher content of nitrogen (7.8 wt\%) and its large proportion of desired chemical environment, which could be established by utilizing the high level of carbon unsaturation around the pore openings.

}, issn = {1754-5692}, doi = {10.1039/c3ee43648a}, author = {Palaniselvam, Thangavelu and Valappil, Manila Ozhukil and Illathvalappil, Rajith and Kurungot, Sreekumar} } @article { ISI:000344997500118, title = {Nitrogen-doped graphene interpenetrated 3D Ni-nanocages: efficient and stable water-to-dioxygen electrocatalysts}, journal = {Nanoscale}, volume = {6}, number = {21}, year = {2014}, month = {SEP}, pages = {13179-13187}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Herein, we report the synthesis of a nitrogen-doped graphene (NGr) interpenetrated 3D Ni-nanocage (Ni-NGr) electrocatalyst by a simple water-in-oil (w/o) emulsion technique for oxidation of water to dioxygen. Correlation of adsorption of NGr and subsequent interpenetration through the specific surface plane of nickel particles as well as the concomitant interaction of N and C with Ni in the nano-regime has been investigated. Apart from the benefits of the synergistic interactions between Ni, N, and C, the overall integrity of the structure and its intra-molecular connectivity within the framework help in achieving better oxygen evolution characteristics at a significantly reduced overpotential. The engineered Ni-NGr nanocage displays a substantially low overpotential of similar to 290 mV at a practical current density of 20 mA cm(-2) in 0.1 M KOH. In comparison, NGr and Ni-particles as separate entities give overpotentials of similar to 570 and similar to 370 mV under similar conditions. Moreover, the long term stability of Ni-NGr was investigated by anodic potential cycling for 500 cycles and an 8.5\% increment in the overpotential at 20 mA cm(-2) was observed. Additionally, a chronoamperometric test was performed for 15 h at 20 mA cm(-2), which highlights the better sustainability of Ni-NGr under the actual operating conditions. Finally, the quantitative estimation of evolved oxygen was monitored by gas chromatography and was found to be 70 mmol h(-1) g(-1) of oxygen, which is constant in the second cycle as well.

}, issn = {2040-3364}, doi = {10.1039/c4nr03578j}, author = {Dhavale, Vishal M. and Gaikwad, Sachin S. and George, Leena and Devi, R. Nandini and Kurungot, Sreekumar} } @article { ISI:000332124800027, title = {Post modification of MOF derived carbon via g-C3N4 entrapment for an efficient metal-free oxygen reduction reaction}, journal = {Chemical Communications}, volume = {50}, number = {25}, year = {2014}, month = {FEB}, pages = {3363-3366}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

High surface area carbon with a nitrogen content of 7.0\% is derived from MOF via in situ g-C3N4 formation. The material shows excellent ORR activity with an onset potential of 0.035 V (vs. Hg/HgO) in alkaline medium apart from high durability and strong disinclination towards methanol crossover.

}, issn = {1359-7345}, doi = {10.1039/c3cc47620k}, author = {Pandiaraj, Sekar and Aiyappa, Harshitha Barike and Banerjee, Rahul and Kurungot, Sreekumar} } @article {46395, title = {Post-synthetically modified porous covalent framework (PCF) for high proton conduction}, journal = {Acta Crystallographica A-Foundation and Advances}, volume = {70}, year = {2014}, month = {MAY}, pages = {C1156}, type = {Meeting Abstract}, keywords = {Porous Covalent Framework, Post-synthetic Modification, proton conduction}, issn = {2053-2733}, author = {Samanta, Partha and Desai, Aamod and Anothumakkool, Bihag and Shirolkar, Mandar and Karmakar, Avishek and Kurungot, Sreekumar and Ghosh, Sujit} } @article { ISI:000331861500013, title = {Structure and dynamics of benzyl-NX3 (X = Me, Et) trifluoromethanesulfonate ionic liquids}, journal = {Journal of Physical Chemistry B}, volume = {118}, number = {7}, year = {2014}, month = {FEB}, pages = {1831-1838}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Ammonium-based benzyl-NX3 (X = methyl, ethyl) trifluoromethanesulfonate (TFA) ionic liquids (ILs) are low cost, nontoxic, thermally stable ion-conducting electrolytes in fuel cells and batteries. In the present study, we have characterized the structure and dynamics of these ILs using molecular dynamics (MD) simulations and ionic conductivity using electro-chemical impedance spectroscopy (EIS) at varying temperature and relative humidity (RH). Results from MD simulations predict that cation-cation and cation-anion interactions are stronger in benzyltrimethylammonium (BzTMA) compared to benzyltriethylammonium (BzTEA) that diminish with increase in RH. Further, the BzTMA cations show both C-H/Ph (center of mass of phenyl ring) and cation-Ph interactions whereas BzTEA cations show only strong cation-Ph interactions. The C-H/Ph interactions (psi \>= 90 degrees, d(H-Ph) \<= 4 angstrom, theta \< 50 degrees and d(C.Ph) \<= 4.3 angstrom) in BzTMA cations increase with RH and are highest at RH = 90\%. The cumulative impact of electrostatic, cation/Ph, and C-H/Ph interactions results in lower conductivity of BzTMA-TFA IL compared to BzTEA-TFA IL. The EIS measurements show that the trends in ionic conductivity of ILs at RH = 30 and 90\% are qualitatively similar to the Nernst-Einstein conductivity from MD simulations. The ionic conductivity of BzTEA-TFA IL is similar to 3 times higher than BzTMA-TFA IL at 353 K and RH = 90\%.

}, issn = {1520-6106}, doi = {10.1021/jp410487a}, author = {Sunda, Anurag Prakash and Dhavale, Vishal M. and Kurungot, Sreekumar and Venkatnathan, Arun} } @article { ISI:000330779900044, title = {Synthesis of an efficient heteroatom-doped carbon electro-catalyst for oxygen reduction reaction by pyrolysis of protein-rich pulse flour cooked with SiO2 nanoparticles}, journal = {Physical Chemistry Chemical Physics}, volume = {16}, number = {9}, year = {2014}, month = {JAN}, pages = {4251-4259}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Development of a highly durable, fuel-tolerant, metal-free electro-catalyst for oxygen reduction reaction (ORR) is essential for robust and cost-effective Anion Exchange Membrane Fuel Cells (AEMFCs). Herein, we report the development of a nitrogen-doped (N-doped) hierarchically porous carbon-based efficient ORR electrocatalyst from protein-rich pulses. The process involves 3D silica nanoparticle templating of the pulse flour(s) followed by their double pyrolysis. The detailed experiments are performed on gram flour (derived from chickpeas) without any in situ/ex situ addition of dopants. The N-doped porous carbon thus generated shows remarkable electrocatalytic activity towards ORR in the alkaline medium. The oxygen reduction on this material follows the desired 4-electron transfer mechanism involving the direct reduction pathway. Additionally, the synthesized carbon catalyst also exhibits good electrochemical stability and fuel tolerance. The results are also obtained and compared with the case of soybean flour having higher nitrogen content to highlight the significance of different parameters in the ORR catalyst performance.

}, issn = {1463-9076}, doi = {10.1039/c3cp55396e}, author = {Gokhale, Rohan and Unni, SreeKuttan M. and Puthusseri, Dhanya and Kurungot, Sreekumar and Ogale, Satishchandra} } @article { ISI:000331774700017, title = {Two-in-one: inherent anhydrous and water-assisted high proton conduction in a 3D metal-organic framework}, journal = {Angewandte Chemie-International Edition}, volume = {53}, number = {10}, year = {2014}, month = {MAR}, pages = {2638-2642}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

The development of solid-state proton-conducting materials with high conductivity that operate under both anhydrous and humidified conditions is currently of great interest in fuel-cell technology. A 3Dmetal-organic framework (MOF) with acid-base pairs in its coordination space that efficiently conducts protons under both anhydrous and humid conditions has now been developed. The anhydrous proton conductivity for this MOF is among the highest values that have been reported for MOF materials, whereas its water-assisted proton conductivity is comparable to that of the organic polymer Nafion, which is currently used for practical applications. Unlike other MOFs, which conduct protons either under anhydrous or humid conditions, this compound should represent a considerable advance in the development of efficient solid-state proton-conducting materials that work under both anhydrous and humid conditions.

}, keywords = {conducting materials, fuel cells, metal-organic frameworks, porous materials, proton conduction}, issn = {1433-7851}, doi = {10.1002/anie.201309077}, author = {Nagarkar, Sanjog S. and Unni, SreeKuttan M. and Sharma, Amitosh and Kurungot, Sreekumar and Ghosh, Sujit K.} } @article { ISI:000353177000029, title = {3D polyaniline porous layer anchored pillared graphene sheets: enhanced interface joined with high conductivity for better charge storage applications}, journal = {ACS Applied Materials \& Interfaces}, volume = {7}, number = {14}, year = {2015}, month = {APR}, pages = {7661-7669}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Here, we report synthesis of a 3-dimensional (3D) porous polyaniline (PANI) anchored on pillared graphene (G-PANI-PA) as an efficient charge storage material for supercapacitor applications. Benzoic acid (BA) anchored graphene, having spatially separated graphene layers (G-Bz-COOH), was used as a structure controlling support whereas 3D PANI growth has been achieved by a simple chemical oxidation of aniline in the presence of phytic acid (PA). The BA groups on G-Bz-COOH play a critical role in preventing the restacking of graphene to achieve a high surface area of 472 m(2)/g compared to reduced graphene oxide (RGO, 290 m(2)/g). The carboxylic acid (-COOH) group controls the rate of polymerization to achieve a compact polymer structure with micropores whereas the chelating nature of PA plays a crucial role to achieve the 3D growth pattern of PANI. This type of controlled interplay helps G-PANI-PA to achieve a high conductivity of 3.74 S/cm all the while maintaining a high surface area of 330 m(2)/g compared to PANI-PA (0.4 S/cm and 60 m(2)/g). G-PANI-PA thus conceives the characteristics required for facile charge mobility during fast charge-discharge cycles, which results in a high specific capacitance of 652 F/g for the composite. Owing to the high surface area along with high conductivity, G-PANI-PA displays a stable specific capacitance of 547 F/g even with a high mass loading of 3 mg/cm(2), an enhanced areal capacitance of 1.52 F/cm(2), and a volumetric capacitance of 122 F/cm(3). The reduced charge-transfer resistance (RCT) of 0.67 O displayed by G-PANI-PA compared to pure PANI (0.79 O) stands out as valid evidence of the improved charge mobility achieved by the system by growing the 3D PANI layer along the spatially separated layers of the graphene sheets. The low RCT helps the system to display capacitance retention as high as 65\% even under a high current dragging condition of 10 A/g. High charge/discharge rates and good cycling stability are the other highlights of the supercapacitor system derived from this composite material.

}, keywords = {durability, ionic accessibility, phytic acid, pillaring, polyaniline, restacking}, issn = {1944-8244}, doi = {10.1021/acsami.5b00504}, author = {Sekar, Pandiaraj and Anothumakkool, Bihag and Kurungot, Sreekumar} } @article { ISI:000364323300003, title = {Can enantiomer ligands produce structurally distinct homochiral MOFs?}, journal = {CrystEngComm}, volume = {17}, number = {43}, year = {2015}, month = {SEP}, pages = {8202-8206}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Here, we report a self-assembled homochiral metal-organic framework [Cu-1.5(H2LL-leu)(Ac)H2O](n)center dot 3H(2)O (1) obtained from an L-leucine-derived ligand (H4L(L-leu)) and Cu(Ac)(2)center dot H2O in a 1 : 1 ratio. Coordination-induced conformational change in the ligand has been monitored by circular dichroism which has been further attested by synthesizing a D-leucine-containing enantiomer H4L D-leu and its Cu(II) complex [Cu-1.5(H2LD-leu)H2O](n)center dot 10H(2)O (2). Structure determination revealed entirely different structures for the homochiral MOFs (1 and 2) obtained from the L/D-leucine-derived enantiomer ligands under analogous reaction conditions. Further, structural dissimilarity in these MOFs has been judicially supported by proton conductance studies. MOF 1 shows higher proton (10(-5) S cm(-1)) conductance in comparison to 2 (10(-6) S cm(-1)) due to dissimilar alignment of the hydrogen-bonded water molecules in the hydrophilic pocket as well as crystal packing.

}, issn = {1466-8033}, doi = {10.1039/c5ce01180a}, author = {Dubey, Mrigendra and Kumar, Ashish and Dhavale, Vishal M. and Kurungot, Sreekumar and Pandey, Daya Shankar} } @article { ISI:000364355500053, title = {Carbon nanohorn-derived graphene nanotubes as a platinum-free fuel cell cathode}, journal = {ACS Applied Materials \& Interfaces}, volume = {7}, number = {43}, year = {2015}, month = {NOV}, pages = {24256-24264}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Current low-temperature fuel cell research mainly focuses on the development of efficient nonprecious electrocatalysts for the reduction of dioxygen molecule due to the reasons like exorbitant cost and scarcity of the current state-of-the-art Pt-based catalysts. As a potential alternative to such costly electrocatalysts, we report here the preparation of an efficient graphene nanotube based oxygen reduction electrocatalyst which has been derived from single walled nanohorns, comprising a thin layer of graphene nanotubes and encapsulated iron oxide nanopartides (FeGNT). FeGNT shows a surface area of 750 m(2)/g, which is the highest ever reported among the metal encapsulated nanotubes. Moreover, the graphene protected iron oxide nanoparticles assist the system to attain efficient distribution of Fe-N-x and quaternary nitrogen based active reaction centers, which provides better activity and stability toward the oxygen reduction reaction (ORR) in acidic as well as alkaline conditions. Single cell performance of a proton exchange membrane fuel cell by using FeGNT as the cathode catalyst delivered a maximum power density of 200 mW cm(-2) with Nafion as the proton exchange membrane at 60 degrees C. The facile synthesis strategy with iron oxide encapsulated graphitic carbon morphology opens up a new horizon of hope toward developing Pt-free fuel cells and metal-air batteries along with its applicability in other energy conversion and storage devices.

}, keywords = {carbon nanohorns, carbon nanotube, electrocatalyst, fuel cell, oxygen reduction reaction}, issn = {1944-8244}, doi = {10.1021/acsami.5b07802}, author = {Unni, SreeKuttan M. and Illathvalappil, Rajith and Bhange, Siddheshwar N. and Puthenpediakkal, Hasna and Kurungot, Sreekumar} } @article { ISI:000355638100042, title = {Coherent fusion of water array and protonated amine in a metal-sulfate-based coordination polymer for proton conduction}, journal = {Inorganic Chemistry}, volume = {54}, number = {11}, year = {2015}, month = {JUN}, pages = {5366-5371}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A new function of metal-sulfate-based co-ordination polymer (CP) for proton,conduction Was investigated through rational integration of a continuous water array and protonated amine in the coordination space of the CP. The H-bonded arrays of watet molecules along with nitrogen-rich aromatic cation (protonated melamine) facilitate proton conduction in the compound under humid conditions. Although several reports of metal-oxalate/phosphate-based CPs showing proton conduction are known, this is the first designed synthesis of a metal sulfate-based CP bearing-Water arrays functioning as a solid-state proton conductor:

}, issn = {0020-1669}, doi = {10.1021/acs.inorgchem.5b00416}, author = {Manna, Biplab and Anothumakkool, Bihag and Desai, Aamod V. and Samanta, Partha and Kurungot, Sreekumar and Ghosh, Sujit K.} } @article { ISI:000362819600016, title = {CoSe2 supported on nitrogen-doped carbon nanohorns as a methanol-tolerant cathode for air-breathing microlaminar flow fuel cells}, journal = {Chemelectrochem}, volume = {2}, number = {9}, year = {2015}, month = {SEP}, pages = {1339-1345}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

The synthesis of CoSe2 nanoparticles supported on nitrogendoped carbon nanohorns (CoSe2/NCNH) and the influence of the interaction of the metal centre with the NCNH on the oxygen reduction reaction (ORR) are reported. CoSe2/NCNH shows a 50 mV lower onset overpotential and a 150 mV positive shift in the half-wave potential compared to CoSe2 supported on carbon and carbon nanohorns. This suggests that the intrinsic activity and the density of active reaction centres of CoSe2 are modified by NCNHs. An air-breathing direct meth-anol microlaminar flow fuel cell (mLFFC) is constructed using CoSe2/NCNH as a methanol-tolerant cathode catalyst. A maximum power density of 10.05 mWcm(-2) and a maximum current density of 124.20 mAcm(-2) are achieved with CoSe2/NCNH compared to the non-doped catalyst, CoSe2/C and Pt/C with 5m methanol as the fuel. The improved activity of CoSe2/ NCNH is attributed to the peculiar morphology and the nitrogen doping of the carbon nanohorns. This catalyst could be a suitable alternative to Pt.

}, keywords = {carbon nanohorns, chalcogenides, fuel cells, oxygen reduction reaction, platinum}, issn = {2196-0216}, doi = {10.1002/celc.201500154}, author = {Unni, SreeKuttan M. and Mora-Hernandez, Juan M. and Kurungot, Sreekumar and Alonso-Vante, Nicolas} } @article { ISI:000350843500006, title = {Cu-Pt nanocage with 3-D electrocatalytic surface as an efficient oxygen reduction electrocatalyst for a primary Zn-air battery}, journal = {ACS Catalysis}, volume = {5}, number = {3}, year = {2015}, month = {MAR}, pages = {1445-1452}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Cu-Pt nanocage (CuPt-NC) intermetallic structures have been prepared by an in situ galvanic displacement reaction. The structures are found to be well organized within the framework demarcated with distinguishing arms, having clear edges and corners with a size of similar to 20 nm. The unique nanocage structure possessing large specific surface area and better structural integrity helps to achieve improved electrochemical oxygen reduction reaction activity and stability in alkaline solution in comparison to the commercially available 20 wt \% Pt/C. CuPt-NC shows 50 mV positive onset potential shift with significantly higher limiting current in comparison to Pt/C. Interestingly, CuPt-NC has shown 2.9- and 2.5-fold improved mass activity and specific activity, respectively, for ORR at 0.9 V vs RHE in comparison to Pt/C. Moreover, the stability of CuPt-NC has been tested by an accelerated durability test under alkaline conditions. CuPt-NC has been subsequently utilized as the air electrode in a primary Zn-air battery and is found to possess 1.30- and 1.34-fold improved power density and current density at 1 V, respectively, in comparison to the state-of-the-art Pt/C catalyst. In addition, CuPt-NC has shown several hours of constant discharge stability at 20 mA cm(-2) with a specific capacity of 560 mAh gZn(-1) and energy density of 728 Wh kgZn(-1) in the primary Zn-air battery system.

}, keywords = {3-D electrocatalytic surface, Cu-Pt nanocage, electrocatalyst, galvanic displacement, oxygen reduction reaction, solvothermal method, Zn-air battery}, issn = {2155-5435}, doi = {10.1021/cs501571e}, author = {Dhavale, Vishal M. and Kurungot, Sreekumar} } @article { ISI:000349580800008, title = {Effect of b site coordination environment in the ORR activity in disordered brownmillerites Ba2In2-xCexO5+delta}, journal = {ACS Applied Materials \& Interfaces}, volume = {7}, number = {5}, year = {2015}, month = {FEB}, pages = {3041-3049}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Ba2In2O5 brownmillerites in which the In site is progressively doped with Ce exhibit excellent oxygen reduction activity under alkaline conditions. Ce doping leads to structural changes advantageous for the reaction. Twenty-five percent doping retains the ordered structure of brownmillerite with alternate layers of tetrahedra and octahedra, whereas further increase in Ce concentration creates disorder. Structures with disordered oxygen atoms/vacancies are found to be better oxygen reduction reaction catalysts probably aided by isotropic ionic conduction, and Ba2In0.5Ce1.5O5+delta is the most active. This enhanced activity is correlated to the more symmetric Ce site coordination environment in this compound. Stoichiometric perovskite BaCeO3 with the highest concentration of Ce shows very poor activity emphasizing the importance of oxygen vacancies, which facilitate O-2 adsorption, in tandem with catalytic sites in oxygen reduction reactions.

}, keywords = {brownmillerite, fuel cell, oxygen disorder, oxygen reduction reaction, Rietveld refinement}, issn = {1944-8244}, doi = {10.1021/am5087837}, author = {Jijil, Chamundi P. and Bhange, Siddheshwar N. and Kurungot, Sreekumar and Devi, R. Nandini} } @article { ISI:000353831200020, title = {Electrochemical preparation of nitrogen-doped graphene quantum dots and their size-dependent electrocatalytic activity for oxygen reduction}, journal = {Bulletin of Materials Science}, volume = {38}, number = {2}, year = {2015}, month = {APR}, pages = {435-442}, publisher = {INDIAN ACAD SCIENCES}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

Here we report a remarkable transformation of nitrogen-doped multiwalled carbon nanotubes (MWCNTs) to size selective nitrogen-doped graphene quantum dots (N-GQDs) by a two-step electrochemical method. The sizes of the N-GQDs strongly depend on the applied anodic potential, moreover increasing potential resulted in a smaller size of N-GQDs. These N-GQDs display many unusual size-dependant optoelectronic (blue emission) and electrocatalytic (oxygen reduction) properties. The presence of N dopants in the carbon framework not only causes faster unzipping of MWCNTs but also provides more low activation energy site for enhancing the electrocatalytic activity for technologically daunting reactions like oxygen reduction. The smaller size of N-GQDs has shown better performance as compared to the large N-GQDs. Interestingly, N-GQDs-3 (size = 2.5 +/- 0.3 nm, onset potential = 0.75 V) show a 30-mV higher positive onset potential shift compared to that of N-GQDs-2 (size = 4.7 +/- 0.3 nm, onset potential = 0.72 V) and 70 mV than that of N-GQDs-1 (size = 7.2 +/- 0.3, onset potential = 0.68 V) for oxygen reduction reaction (ORR) in a liquid phase. These result in the size-dependent electrocatalytic activity of N-GQDs for ORR as illustrated by the smaller sized N-GQDs (2.5 +/- 0.3 nm) undoubtedly promising metal-free electrocatalysts for fuel cell applications.

}, keywords = {fuel cells, MWCNTs, N-GQDs, oxygen reduction reaction, unzipping}, issn = {0250-4707}, doi = {10.1007/s12034-014-0834-3}, author = {Shinde, Dhanraj B. and Dhavale, Vishal M. and Kurungot, Sreekumar and Pillai, Vijayamohanan K.} } @article { ISI:000345901600070, title = {Fe(III) phytate metallogel as a prototype anhydrous, intermediate temperature proton conductor}, journal = {Chemical Science}, volume = {6}, number = {1}, year = {2015}, month = {OCT}, pages = {603-607}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A proton conducting metallogel [FNPA; ferric nitrate (FN)-phytic acid (PA)] is synthesized by immobilizing a protogenic ligand (phytic acid) using iron(III) nitrate in DMF. The xerogel shows high proton conductivity of 2.4 x 10(-2) S cm(-1) at 120 degrees C, the best value known among all metal organic materials (MOMs). Marking the first such attempt in MOMs, an electrode made using the xerogel showed a power density of 0.94 mW cm(-2) at 0.6 V under dry fuel cell conditions.

}, issn = {2041-6520}, doi = {10.1039/c4sc02294g}, author = {Aiyappa, Harshitha Barike and Saha, Subhadeep and Wadge, Pritish and Banerjee, Rahul and Kurungot, Sreekumar} } @article { ISI:000362662100024, title = {Layer-separated MoS2 bearing reduced graphene oxide formed by an in situ intercalation-cum-anchoring route mediated by Co(OH)(2) as a Pt-free electrocatalyst for oxygen reduction}, journal = {Nanoscale}, volume = {7}, number = {40}, year = {2015}, month = {SEP}, pages = {16729-16736}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A significant improvement in the electrochemical oxygen reduction reaction (ORR) activity of molybdenum sulphide (MoS2) could be accomplished by its layer separated dispersion on graphene mediated by cobalt hydroxide (Co(OH)(2)) through a hydrothermal process (Co(OH)(2)-MoS2/rGO). The activity make-over in this case is found to be originated from a controlled interplay of the favourable modulations achieved in terms of electrical conductivity, more exposure of the edge planes of MoS2 and a promotional role played by the coexistence of Co(OH)(2) in the proximity of MoS2. Co(OH)(2)-MoS2/rGO displays an oxygen reduction onset potential of 0.855 V and a half wave potential (E-1/2) of 0.731 V vs. RHE in 0.1 M KOH solution, which are much higher than those of the corresponding values (0.708 and 0.349 V, respectively) displayed by the as synthesized pristine MoS2 (P-MoS2) under identical experimental conditions. The Tafel slope corresponding to oxygen reduction for Co(OH)(2)-MoS2/rGO is estimated to be 63 mV dec(-1) compared to 68 mV dec(-1) displayed by the state-of-the-art Pt/C catalyst. The estimated number of electrons transferred during oxygen reduction for Co(OH)(2)-MoS2/rGO is in the range of 3.2-3.6 in the potential range of 0.77 V to 0.07 V, which again stands out as valid evidence on the much favourable mode of oxygen reduction accomplished by the system compared to its pristine counterpart. Overall, the present study, thus, demonstrates a viable strategy of tackling the inherent limitations, such as low electrical conductivity and limited access to the active sites, faced by the layered structures like MoS2 to position them among the group of potential Pt-free electrocatalysts for oxygen reduction.

}, issn = {2040-3364}, doi = {10.1039/c5nr04415d}, author = {Illathvalappil, Rajith and Unni, SreeKuttan M. and Kurungot, Sreekumar} } @article { ISI:000368224600009, title = {Lithium-assisted proton conduction at 150 degrees C in a microporous triazine-phenol polymer}, journal = {Advanced Materials Interfaces}, volume = {2}, number = {16}, year = {2015}, month = {NOV}, pages = {1500301}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, keywords = {conduction, hydrophobic polar frameworks, lithiated polymers, proton conduction, triazine-phenol polymers}, issn = {2196-7350}, doi = {10.1002/admi.201500301}, author = {Nandi, Shyamapada and Dhavale, Vishal M. and Shalini, Sorout and Werner-Zwanziger, Ulrike and Singh, Harpreet and Kurungot, Sreekumar and Vaidhyanathan, Ramanathan} } @article {45879, title = {Low surface energy plane exposed co3o4 nanocubes supported on nitrogen-doped graphene as an electrocatalyst for efficient water oxidation}, journal = {ACS Applied Materials \& Interfaces}, volume = {7}, year = {2015}, month = {JAN }, pages = {442-451}, type = {Article}, issn = {1944-8244}, doi = {10.1021/am506450c}, author = {Singh, Santosh K. and Dhavale, Vishal M. and Kurungot, Sreekumar} } @article { ISI:000365530700031, title = {Nanocrystalline Fe-Fe2O3 particle-deposited N-doped graphene as an activity-modulated Pt-free electrocatalyst for oxygen reduction reaction}, journal = {Nanoscale}, volume = {7}, number = {47}, year = {2015}, month = {OCT}, pages = {20117-20125}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The size-controlled growth of nanocrystalline Fe-Fe2O3 particles (2-3 nm) and their concomitant dispersion on N-doped graphene (Fe-Fe2O3/NGr) could be attained when the mutually assisted redox reaction between NGr and Fe3+ ions could be controlled within the aqueous droplets of a water-in-oil emulsion. The synergistic interaction existing between Fe-Fe2O3 and NGr helped the system to narrow down the overpotential for the oxygen reduction reaction (ORR) by bringing a significant positive shift to the reduction onset potential, which is just 15 mV higher than its Pt-counterpart. In addition, the half-wave potential (E-1/2) of Fe-Fe2O3/NGr is found to be improved by a considerable amount of 135 mV in comparison to the system formed by dispersing Fe-Fe2O3 nanoparticles on reduced graphene oxide (Fe-Fe2O3/RGO), which indicates the presence of a higher number of active sites in Fe-Fe2O3/NGr. Despite this, the ORR kinetics of Fe-Fe2O3/NGr are found to be shifted significantly to the preferred 4-electron-transfer pathway compared to NGr and Fe-Fe2O3/RGO. Consequently, the H2O2\% was found to be reduced by 78.3\% for Fe-Fe2O3/NGr (13.0\%) in comparison to Fe-Fe2O3/RGO (51.2\%) and NGr (41.0\%) at -0.30 V (vs. Hg/HgO). This difference in the yield of H2O2 formed between the systems along with the improvements observed in terms of the oxygen reduction onset and E-1/2 in the case of Fe-Fe2O3/NGr reveals the activity modulation achieved for the latter is due to the coexistence of factors such as the presence of the mixed valancies of iron nanoparticles, small size and homogeneous distribution of Fe-Fe2O3 nanoparticles and the electronic modifications induced by the doped nitrogen in NGr. A controlled interplay of these factors looks like worked favorably in the case of Fe-Fe2O3/NGr. As a realistic system level validation, Fe-Fe2O3/NGr was employed as the cathode electrode of a single cell in a solid alkaline electrolyte membrane fuel cell (AEMFC). The system could display an open circuit voltage (OCV) of 0.73 V and maximum power and current densities of 54.40 mW cm(-2) and 200 mA cm(-2), respectively, which are comparable to the performance characteristics of a similar system derived by using 40 wt\% Pt/C as the cathode electrode.

}, issn = {2040-3364}, doi = {10.1039/c5nr04929f}, author = {Dhavale, Vishal M. and Singh, Santosh K. and Nadeema, Ayasha and Gaikwad, Sachin S. and Kurungot, Sreekumar} } @article {45881, title = {Nitrogen-induced surface area and conductivity modulation of carbon nanohorn and its function as an efficient metal-free oxygen reduction electrocatalyst for anion-exchange membrane fuel cells}, journal = {SMALL}, volume = {11}, year = {2015}, month = {JAN }, pages = {352-360}, type = {Article}, abstract = {

Nitrogen-doped carbon morphologies have been proven to be better alternatives to Pt in polymer-electrolyte membrane (PEM) fuel cells. However, efficient modulation of the active sites by the simultaneous escalation of the porosity and nitrogen doping, without affecting the intrinsic electrical conductivity, still remains to be solved. Here, a simple strategy is reported to solve this issue by treating single-walled carbon nanohorn (SWCNH) with urea at 800 degrees C. The resulting nitrogen-doped carbon nanohorn shows a high surface area of 1836 m(2) g(-1) along with an increased electron conductivity, which are the pre-requisites of an electro catalyst. The nitrogen-doped nanohorn annealed at 800 degrees C (N-800) also shows a high oxygen reduction activity (ORR). Because of the high weight percentage of pyridinic nitrogen coordination in N-800, the present catalyst shows a clear 4-electron reduction pathway at only 50 mV overpotential and 16 mV negative shift in the half-wave potential for ORR compared to Pt/C along with a high fuel selectivity and electrochemical stability. More importantly, a membrane electrode assembly (MEA) based on N-800 provides a maximum power density of 30 mW cm(-2) under anion-exchange membrane fuel cell (AEMFC) testing conditions. Thus, with its remarkable set of physical and electrochemical properties, this material has the potential to perform as an efficient Pt-free electrode for AEMFCs.

}, issn = {1613-6810}, doi = {10.1002/smll.201303892}, author = {Unni, SreeKuttan M. and Bhange, Siddheshwar N. and Illathvalappil, Rajith and Mutneja, Nisha and Patil, Kasinath R. and Kurungot, Sreekumar} } @article { ISI:000349667700031, title = {Surface-modified single wall carbon nanohorn as an effective electrocatalyst for platinum-free fuel cell cathodes}, journal = {Journal of Materials Chemistry A}, volume = {3}, number = {8}, year = {2015}, month = {JAN}, pages = {4361-4367}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Platinum (Pt) and its alloys are routinely used in the cathodes of polymer electrolyte membrane fuel cells (PEMFCs) due to their high electrocatalytic activity in oxygen reduction reactions (ORRs). A variety of alternative materials have been examined as alternatives to Pt, but most of these had low activity and their performance deteriorated even further in use. In the present study an alternate electrocatalyst has been examined, obtained by a simple surface modification of single-walled carbon nanohorns by simultaneous doping with Fe and N at 900 degrees C (FeNCNH-900). This had an ORR activity superior to that of 40 wt\% Pt on carbon (Pt/C). Compared to Pt/C, FeNCNH-900 gave a 30 mV improvement in onset potential and a 20 mV gain in half-wave potential in an ORR. Its high activity is the result of the simultaneous modulation achieved by the high surface area and the microporosity of carbon nanohorns, together with the establishment of the desired nitrogen-iron coordinated pyrrolic active centres. The catalyst showed excellent electrochemical stability and, most notably, its ORR activity was still increasing after 1000 cycles. Single-cell fuel cell performance using FeNCNH-900 as cathode catalyst showed a maximum power density of 35 mW cm(-2) under alkaline conditions.

}, issn = {2050-7488}, doi = {10.1039/c4ta05092d}, author = {Unni, SreeKuttan M. and Ramadas, Sarath and Illathvalappil, Rajith and Bhange, Siddheshwar N. and Kurungot, Sreekumar} } @article { ISI:000362243500018, title = {Surface-tuned Co3O4 nanoparticles dispersed on nitrogen-doped graphene as an efficient cathode electrocatalyst for mechanical rechargeable zinc-air battery application}, journal = {ACS Applied Materials \& Interfaces}, volume = {7}, number = {38}, year = {2015}, month = {SEP}, pages = {21138-21149}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The most vital component of the fuel cells and metal air batteries is the electrocatalyst, which can facilitate the oxygen reduction reaction (ORR) at a significantly reduced overpotential. The present work deals with the development of surface-tuned cobalt oxide (Co3O4) nanoparticles dispersed on nitrogen-doped graphene as a potential ORR electrocatalyst possessing some unique advantages. The thermally reduced nitrogen-doped graphene (NGr) was decorated with three different morphologies of Co3O4 nanoparticles, viz., cubic, blunt edged cubic, and spherical, by using a simple hydrothermal method. We found that the spherical Co3O4 nanoparticle supported NGr catalyst (Co3O4-SP/NGr-24h) has acquired a significant activity makeover to display the ORR activity closely matching with the state-of-the-art Pt supported carbon (PtC) catalyst in alkaline medium. Subsequently, the Co3O4-SP/NGr-24h catalyst has been utilized as the air electrode in a Zn-air battery, which was found to show comparable performance to the system derived from PtC. Co3O4-SP/NGr-24h catalyst has shown several hours of flat discharge profile at the discharge rates of 10, 20, and 50 mA/cm(2) with a specific capacity and energy density of similar to 590 mAh/g(-zn) and,840 Wh/kg(-zn), respectively, in the primary Zn-air battery system. In conjunction, Co3O4-SP/NGr-24h has outperformed as an air electrode in mechanical rechargeable Zn-air battery as well, which has shown consistent flat discharge profile with minimal voltage loss at a discharge rate of 50 mA/cm(2). The present results, thus demonstrate that the proper combination of the tuned morphology of Co3O4 with NGr will be a promising and inexpensive material for efficient and ecofriendly cathodes for Zn-air batteries.

}, keywords = {electrocatalyst, mixed facets, oxygen reduction reaction, rechargeable zinc-air battery, surface morphology}, issn = {1944-8244}, doi = {10.1021/acsami.5b04865}, author = {Singh, Santosh K. and Dhavale, Vishal M. and Kurungot, Sreekumar} } @article { ISI:000354910500021, title = {Switching closed-shell to open-shell phenalenyl: toward designing electroactive materials}, journal = {Journal of the American Chemical Society}, volume = {137}, number = {18}, year = {2015}, month = {MAY}, pages = {5955-5960}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Open-shell phenalenyl chemistry started more than half a century back, and the first solid-state phenalenyl radical was realized only 15 years ago highlighting the synthetic challenges associated in stabilizing carbon-based radical chemistry, though it has great promise as building blocks for molecular electronics and multifunctional materials. Alternatively; stable closed-shell phenalenyl has tremendous potential as it can be utilized, to create an in situ open-shell state by external spin injection. In the present study, we have designed a closed-shell phenalenyl-based iron(III) complex, Fe-III(PLY)(3) (PLY-H = 9-hydroxyphenalenone) displaying an excellent electrocatalytic property as cathode material for one compartment membraneless H2O2 fuel cell. The power density output Of Fe-III(PLY)(3) is nearly 15-fold higher than the structurally related model compound Fe-III(acac)(3) (acac = acetylacetonate) and nearly 140-fold higher than an earlier reported mononuclear Fe(III) complex; Fe-III(Pc)Cl (Pc = pthalocyaninate), highlighting the role of switchable closed-shell phenalenyl moiety for electron-transfer process in designing electroactive materials.

}, issn = {0002-7863}, doi = {10.1021/jacs.5b00272}, author = {Pariyar, Anand and Vijaykumar, Gonela and Bhunia, Mrinal and Dey, Suman Kr. and Singh, Santosh K. and Kurungot, Sreekumar and Mandal, Swadhin K.} } @article { ISI:000382246400001, title = {1000-fold enhancement in proton conductivity of a MOF using post-synthetically anchored proton transporters}, journal = {Scientific Reports}, volume = {6}, year = {2016}, month = {AUG}, pages = {32489}, publisher = {NATURE PUBLISHING GROUP}, address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND}, abstract = {

Pyridinol, a coordinating zwitter-ionic species serves as stoichiometrically loadable and non-leachable proton carrier. The partial replacement of the pyridinol by stronger hydrogen bonding, coordinating guest, ethylene glycol (EG), offers 1000-fold enhancement in conductivity (10(-6) to 10(-3) Scm(-1)) with record low activation energy (0.11 eV). Atomic modeling coupled with C-13-SSNMR provides insights into the potential proton conduction pathway functionalized with post-synthetically anchored dynamic proton transporting EG moieties.

}, issn = {2045-2322}, doi = {10.1038/srep32489}, author = {Shalini, Sorout and Dhavale, Vishal M. and Eldho, Kavalakal Mathai and Kurungot, Sreekumar and Ajithkumar, Thalasseril G. and Vaidhyanathan, Ramanathan} } @article {45650, title = {1D alignment of PEDOT in a buckypaper for high-performance solid supercapacitors}, journal = {Chemelectrochem}, volume = {3}, year = {2016}, month = {SEP}, pages = {1329-1336}, type = {Article}, abstract = {

A flexible solid-state supercapacitor is prepared from carbon nanotube (CNT)-based buckypaper after forming a thin layer of polyethylenedioxythiophene (PEDOT) on the surface of the CNTs in the paper. A highly conducting PEDOT phase is obtained by interfacial polymerization, in which polymerization is confined at the interface of two immiscible liquids. The hydrophilic interaction between the functionalized CNTs and the oxidizing agent (iron perchlorate, Fe(ClO4)(3)), which is located in the aqueous phase, and the restricted interaction of the oxidizing agent with the EDOT monomer in the organic layer at the immiscible interface play a vital role in establishing a uniform and aggregate-free growth pattern of PEDOT on CNT. By carefully optimizing the amount of polymer in the paper, an electrode with a sheet resistance of 3.4(-1) and equivalent series resistance of 0.95 can be prepared. A thin and flexible solid-state supercapacitor device with an overall thickness of 210m is made by using this paper as the electrodes and poly(vinyl alcohol)/lithium chloride as the gel electrolyte. The power density and energy density of the electrode are 9.94Wcm(-3) and 8.85mWhcm(-3), respectively. The device also delivers a high volumetric capacitance of 18Fcm(-3) and areal capacitance of 354mFcm(-2). The demonstrated strategy is scalable and hence the process can be conveniently applied to prepare large-area PEDOT-modified buckypapers in a short time.

}, keywords = {Carbon, Energy storage, nanotubes, polymerization, Supercapacitors}, issn = {2196-0216}, doi = {10.1002/celc.201600229}, author = {Soni, Roby and Anothumakkool, Bihag and Kurungot, Sreekumar} } @article { ISI:000378973100031, title = {Cobalt-modified covalent organic framework as a robust wateroxidation electrocatalyst}, journal = {Chemistry of Materials}, volume = {28}, number = {12}, year = {2016}, month = {JUN}, pages = {4375-4379}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The development of stable, efficient oxygen evolution reaction (OER) catalyst capable of oxidizing water is one of the premier challenges in the conversion of solar energy to electrical energy, because of its poor kinetics. Herein, a bipyridine-containing covalent organic framework (TpBpy) is utilized as an OER catalyst by way of engineering active Co(II) ions into its porous framework. The as-obtained Co-TpBpy retains a highly accessible surface area (450 m(2)/g) with exceptional stability, even after 1000 cycles and 24 h of OER activity in phosphate buffer under neutral pH conditions with an overpotential of 400 mV at a current density of 1 mA/cm(2). The unusual catalytic stability of Co-TpBpy arises from the synergetic effect of the inherent porosity and presence of coordinating units in the COF skeleton.

}, issn = {0897-4756}, doi = {10.1021/acs.chemmater.6b01370}, author = {Aiyappa, Harshitha Barike and Thote, Jayshri and Shinde, Digambar Balaji and Banerjee, Rahul and Kurungot, Sreekumar} } @article { ISI:000366859200017, title = {Conjugated porous polymers as precursors for electrocatalysts and storage electrode materials}, journal = {Chemical Communications}, volume = {52}, number = {2}, year = {2016}, month = {OCT}, pages = {316-318}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Conjugated porous polymers were used as precursors to prepare nitrogen and sulphur doped carbon atoms, which were then used for oxygen reduction and energy storage.

}, issn = {1359-7345}, doi = {10.1039/c5cc08148c}, author = {Bhosale, Manik E. and Illathvalappil, Rajith and Kurungot, Sreekumar and Krishnamoorthy, Kothandam} } @article {45827, title = {Coordination polymers of Fe(III) and Al(III) ions with TCA ligand: distinctive fluorescence, CO2 uptake, redox-activity and oxygen evolution reaction}, journal = {Dalton Transactions}, volume = {45}, year = {2016}, month = {FEB}, pages = {6901-6908}, type = {Article}, abstract = {

Fe and Al belong to different groups in the periodic table, one from the p-block and the other from the d-block. In spite of their different groups, they have the similarity of exhibiting a stable 3+ oxidation state. Here we have prepared Fe(III) and Al(III) based coordination polymers in the form of metal-organic gels with the 4,4{\textquoteright}, 4 {\textquoteleft}{\textquoteright}-tricarboxyltriphenylamine (TCA) ligand, namely Fe-TCA and Al-TCA, and evaluated some important physicochemical properties. Specifically, the electrical conductivity, redox-activity, porosity, and electrocatalytic activity (oxygen evolution reaction) of the Fe-TCA system were noted to be remarkably higher than those of the Al-TCA system. As for the photophysical properties, almost complete quenching of the fluorescence originating from TCA was observed in case of the Fe-TCA system, whereas for the Al-TCA system a significant retention of fluorescence with red-shifted emission was observed. Quantum mechanical calculations based on density functional theory (DFT) were performed to unravel the origin of such discriminative behaviour of these coordination polymer systems.

}, issn = {1477-9226}, doi = {10.1039/c6dt00009f}, author = {Dhara, Barun and Sappati, Subrahmanyam and Singh, Santosh K. and Kurungot, Sreekumar and Ghosh, Prasenjit and Ballav, Nirmalya} } @article {45636, title = {Graphene oxide sheathed ZIF-8 microcrystals: engineered precursors of nitrogen-doped porous carbon for efficient oxygen reduction reaction (ORR) electrocatalysis}, journal = {ACS Applied Materials \& Interfaces}, volume = {8}, year = {2016}, month = {NOV}, pages = {29373-29382}, type = {Article}, abstract = {

Nitrogen containing mesoporous carbon obtained by the pyrolysis of graphene oxide (GO) wrapped ZIF-8 (Zeolitic Imidazolate Frameworks-8) micro crystals is demonstrated to be an efficient catalyst for the oxygen reduction reaction (ORR). ZIF-8 synthesis in the presence of GO sheets helped to realize layers of graphene oxide over ZIF-8 microcrystals and the sphere-like structures thus obtained, on heat treatment, transformed to highly porous carbon with a nitrogen content of about 6.12\% and surface area of 502 m(2)/g. These catalysts with a typical micromeso porous architecture exhibited an onset potential of 0.88Vvs RHE in a four electron pathway and also demonstrated superior durability in alkaline medium compared to that of the commercial Pt/C catalyst. The N-doped porous carbon derived from GO sheathed ZIF-8 core shell structures could therefore be employed as an efficient electrocatalyst for fuel cell applications.

}, keywords = {alkaline fuel cell, graphene oxide, N-doped carbon, oxygen reduction reaction, porous carbon, ZIF-8}, issn = {1944-8244}, doi = {10.1021/acsami.6b06979}, author = {Thomas, Minju and Illathvalappi, Rajith and Kurungot, Sreekumar and Nair, Balagopal N. and Mohamed, Abdul Azeez Peer and Anilkumar, Gopinathan M. and Yamaguchi, Takeo and Hareesh, U. S.} } @article { ISI:000378715600028, title = {High hydroxide conductivity in a chemically stable crystalline metal-organic framework containing a water-hydroxide supramolecular chain}, journal = {Chemical Communications}, volume = {52}, number = {54}, year = {2016}, month = {JUN}, pages = {8459-8462}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A chemically stable cationic MOF encapsulating an in situ formed water-hydroxide supramolecular anionic chain is realized for high hydroxide (OH-) ion conductivity in the solid-state (Type A). High OH- ion conductivity and low activation energy of the MOF demonstrate the advantage of the in situ incorporation of OH- ions to achieve efficient OH- ion conduction in the solid-state.

}, issn = {1359-7345}, doi = {10.1039/c6cc04436k}, author = {Nagarkar, Sanjog S. and Anothumakkool, Bihag and Desai, Aamod V. and Shirolkar, Mandar M. and Kurungot, Sreekumar and Ghosh, Sujit K.} } @article {45832, title = {High-index faceted Au nanocrystals with highly controllable optical properties and electro-catalytic activity}, journal = {Nanoscale}, volume = {8}, year = {2016}, month = {NOV}, pages = {19224-19228}, type = {Article}, abstract = {

We introduce a new and naturally abundant mild reducing agent, tannic acid, to improve the seed-mediated growth method for the synthesis of elongated tetrahexahedral Au nanocrystals enclosed with high-index (730) planes, at room-temperature. The control of the dimensions, plasmonics and electro-catalysis of such high-index faceted nanocrystals is remarkable.

}, issn = {2040-3364}, doi = {10.1039/c6nr06922c}, author = {Rajendra, Ranguwar and Gangadharan, Pranav K. and Tripathi, Shalini and Kurungot, Sreekumar and Ballav, Nirmalya} } @article { ISI:000368651100021, title = {High-Performance flexible solid-state supercapacitor with an extended nanoregime interface through in situ polymer electrolyte generation}, journal = {ACS Applied Materials \& Interfaces}, volume = {8}, number = {2}, year = {2016}, month = {JAN}, pages = {1233-1241}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

{Here, we report an efficient strategy by which a significantly enhanced electrodeelectrolyte interface in an electrode for supercapacitor application could be accomplished by allowing in situ polymer gel electrolyte generation inside the nanopores of the electrodes. This unique and highly efficient strategy could be conceived by judiciously maintaining ultraviolet-triggered polymerization of a monomer mixture in the presence of a high-surface-area porous carbon. The method is very simple and scalable, and a prototype, flexible solid-state supercapacitor could even be demonstrated in an encapsulation-free condition by using the commercial-grade electrodes (thickness = 150 mu m

}, keywords = {cyclic voltametry, impedance analysis, in situ polymer generation, interface, polymer electrolyte, supercapacitor}, issn = {1944-8244}, doi = {10.1021/acsami.5b09677}, author = {Anothumakkool, Bihag and Torris, Arun A. T. and Veeliyath, Sajna and Vijayakumar, Vidyanand and Badiger, Manohar V. and Kurungot, Sreekumar} } @article {45652, title = {Hydrogen-bonded organic frameworks (HOFs): a new class of porous crystalline proton-conducting materials}, journal = {Angewandte Chemie-International Edition}, volume = {55}, year = {2016}, month = {AUG }, pages = {10667-10671}, type = {Article}, abstract = {

Two porous hydrogen-bonded organic frameworks (HOFs) based on arene sulfonates and guanidinium ions are reported. As a result of the presence of ionic backbones appended with protonic source, the compounds exhibit ultra-high proton conduction values (sigma) 0.75x 10(-2)Scm(-1) and 1.8x10(-2)Scm(-1) under humidified conditions. Also, they have very low activation energy values and the highest proton conductivity at ambient conditions (low humidity and at moderate temperature) among porous crystalline materials, such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). These values are not only comparable to the conventionally used proton exchange membranes, such as Nafion used in fuel cell technologies, but is also the highest value reported in organic-based porous architectures. Notably, this report inaugurates the usage of crystalline hydrogen-bonded porous organic frameworks as solid-state proton conducting materials.

}, keywords = {guanidinium, hydrogen-bonded organic frameworks, porous crystalline frameworks, proton conduction, sulfonates}, issn = {1433-7851}, doi = {10.1002/anie.201604534}, author = {Karmakar, Avishek and Illathvalappil, Rajith and Anothumakkool, Bihag and Sen, Arunabha and Samanta, Partha and Desai, Aamod V. and Kurungot, Sreekumar and Ghosh, Sujit K.} } @article {45630, title = {Low band gap benzimidazole COF supported Ni3N as highly active OER catalyst}, journal = {Advanced Energy Materials}, volume = {6}, year = {2016}, month = {DEC }, pages = {Article No:1601189}, abstract = {

Covalent organic frameworks (COFs) have structures and morphologies closely resembling graphenes, whose modular construction permits atomiclevel manipulations. This, combined with their porous structure, makes them excellent catalyst supports. Here, the high electrocatalytic activity of a composite, formed by supporting Ni3N nanoparticles on a benzimidazole COF, for oxygen evolution reaction is shown. The composite oxidizes alkaline water with a near-record low overpotential of 230 mV @ 10 mA cm(-2) (eta(10)). This high activity is attributed to the ability of the COF to confine the Ni3N nanoparticles to size regimes otherwise difficult to obtain and to its low band gap character (1.49 eV) arising from the synergy between the conducting Ni3N nanoparticles and the pi-conjugated COF. The COF itself, as a metalfree self-standing framework, has an oxygen evolution reaction activity with 10 of 400 mV. The periodic structure of the COF makes it serve as a matrix to disperse the catalytically active Ni3N nanoparticles favoring their high accessibility and thereby good charge-transport within the composite. This is evident from the amount of O-2 evolved (230 mmol h(-1) g(-1)), which, to the best of our knowledge, is the highest reported. The work reveals the emergence of COF as supports for electrocatalysts.

}, issn = {1614-6832}, doi = {10.1002/aenm.201601189}, author = {Nandi, Shyamapada and Singh, Santosh Kumar and Mullangi, Dinesh and Illathvalappil, Rajith and George, Leena and Vinod, Chathakudath P. and Kurungot, Sreekumar and Vaidhyanathan, Ramanathan} } @article { ISI:000379314700006, title = {Low-overpotential electrocatalytic water splitting with noble-metal-free nanoparticles supported in a sp(3) n-rich flexible COF}, journal = {Advanced Energy Materials}, volume = {6}, number = {13}, year = {2016}, month = {JUL}, pages = {Article No. 1600110}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Covalent organic frameworks (COFs) are crystalline organic polymers with tunable structures. Here, a COF is prepared using building units with highly flexible tetrahedral sp(3) nitrogens. This flexibility gives rise to structural changes which generate mesopores capable of confining very small (\<2 nm sized) non-noble-metal-based nanoparticles (NPs). This nanocomposite shows exceptional activity toward the oxygen-evolution reaction from alkaline water with an overpotential of 258 mV at a current density of 10 mA cm(-2). The overpotential observed in the COF-nanoparticle system is the best in class, and is close to the current record of approximate to 200 mV for any noble-metalfree electrocatalytic water splitting system-the Fe-Co-Ni metal-oxide-film system. Also, it possesses outstanding kinetics (Tafel slope of 38.9 mV dec(-1)) for the reaction. The COF is able to stabilize such small-sized NP in the absence of any capping agent because of the COF-Ni(OH)(2) interactions arising from the N-rich backbone of the COF. Density-functional-theory modeling of the interaction between the hexagonal Ni(OH)(2) nanosheets and the COF shows that in the most favorable configuration the Ni(OH)(2) nanosheets are sandwiched between the sp(3) nitrogens of the adjacent COF layers and this can be crucial to maximizing their synergistic interactions.

}, issn = {1614-6832}, doi = {10.1002/aenm.201600110}, author = {Mullangi, Dinesh and Dhavale, Vishal M. and Shalini, Sorout and Nandi, Shyamapada and Collins, Sean and Woo, Tom and Kurungot, Sreekumar and Vaidhyanathan, Ramanathan} } @article { ISI:000369665800035, title = {Mechanochemically synthesized covalent organic framework as a proton-conducting solid electrolyte}, journal = {Journal of Materials Chemistry A}, volume = {4}, number = {7}, year = {2016}, month = {JAN}, pages = {2682-2690}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Mechanochemistry has become an increasingly important synthetic tool for a waste-free environment. However, the poor quality of the so-derived materials in terms of their crystallinity and porosity has been their major drawback for any practical applications. In this report, we have for the first time successfully leveraged such characteristics to show that the mechanochemically synthesized bipyridine based covalent organic framework (COF) outperforms its conventional solvothermal counterpart as an efficient solid-state electrolyte in PEM fuel cells. Marking the first such attempt in COFs, a Membrane Electrode Assembly (MEA) fabricated using the mechanochemically synthesized COF was observed to inhibit the fuel crossover and build up a stable Open Circuit Voltage (OCV = 0.93 V at 50 degrees C), thereby establishing itself as an effective solid electrolyte material (with a proton conductivity of 1.4 x 10(-2) S cm(-1)), while the solvothermally synthesized COF proved ineffective under similar conditions.

}, issn = {2050-7488}, doi = {10.1039/c5ta10521h}, author = {Shinde, Digambar Balaji and Aiyappa, Harshitha Barike and Bhadra, Mohitosh and Biswal, Bishnu P. and Wadge, Pritish and Kandambeth, Sharath and Garai, Bikash and Kundu, Tanay and Kurungot, Sreekumar and Banerjee, Rahul} } @article { ISI:000373738000011, title = {Nanoporous graphene enriched with Fe/Co-N active sites as a promising oxygen reduction electrocatalyst for anion exchange membrane fuel cells}, journal = {Advanced Functional Materials}, volume = {26}, number = {13}, year = {2016}, month = {APR}, pages = {2150-2162}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Here, a simple but efficient way is demonstrated for the preparation of nanoporous graphene enriched with Fe/Co-nitrogen-doped active sites (Fe/Co-NpGr) as a potential electrocatalyst for the electrochemical oxygen reduction reaction (ORR) applications. Once graphene is converted into porous graphene (pGr) by a controlled oxidative etching process, pGr can be converted into a potential electrocatalyst for ORR by utilizing the created edge sites of pGr for doping nitrogen and subsequently to utilize the doped nitrogens to build Fe/Co coordinated centers (Fe/Co-NpGr). The structural information elucidated using both XPS and TOF-SIMS study indicates the presence of coordination of the M-N (M = Fe and Co)-doped carbon active sites. Creation of this bimetallic coordination assisted by the nitrogen locked at the pore openings is found to be helping the system to substantially reduce the overpotential for ORR. A 30 mV difference in the overpotential () with respect to the standard Pt/C catalyst and high retention in half wave potential after 10 000 cycles in ORR can be attained. A single cell of an anion exchange membrane fuel cell (AEMFC) by using Fe/Co-NpGr as the cathode delivers a maximum power density of approximate to 35 mWcm(-2) compared to 60 mWcm(-2) displayed by the Pt-based system.

}, keywords = {electrocatalyst, nitrogen doping, oxygen reduction reaction, porous grapheme, quantum dots}, issn = {1616-301X}, doi = {10.1002/adfm.201504765}, author = {Palaniselvam, Thangavelu and Kashyap, Varchaswal and Bhange, Siddeswar N. and Baek, Jong-Beom and Kurungot, Sreekumar} } @article { ISI:000374790700031, title = {Nitrogen and sulphur co-doped crumbled graphene for the oxygen reduction reaction with improved activity and stability in acidic medium}, journal = {Journal of Materials Chemistry A}, volume = {4}, number = {16}, year = {2016}, month = {MAR}, pages = {6014-6020}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Non-precious dioxygen reduction electrocatalysts have attracted great attention nowadays for the development of stable, cost-effective proton exchange membrane fuel cells. In line with the development of non-precious electrocatalysts, here we report the synthesis of a platinum-free oxygen reduction electrocatalyst based on nitrogen and sulphur co-doped crumbled graphene with trace amounts of iron. The co-doped crumbled graphene structure was obtained by simple oxidative polymerisation of ethylenedioxythiophene in aqueous solution followed by an annealing process under an inert atmosphere. This new electrocatalyst displays improved oxygen reduction activity and electrochemical stability under acidic conditions. The half-cell reaction of the 1000 degrees C annealed polyethylenedioxythiophene (PF-1000) displays only 0.1 V overpotential in both the onset and half-wave potentials compared to state-of-the-art Pt/C in an acidic environment for the ORR. More importantly, the limiting current of PF-1000 clearly surpasses the limiting current displayed by Pt/C, indicating that the crumbled assembly of the graphene flakes helps the system to expose the active sites and the porous network of the material matrix ensures extended accessibility of active sites to the electrolyte and reagent. The dioxygen reduction kinetics of PF-1000 appear similar to those of Pt/C and the system accomplishes the reduction of the dioxygen molecule through the recommended four-electron reduction pathway. The improved activity and electrochemical stability of PF-1000 are mainly attributed to the enriched and well accessible active reaction centres such as graphitic nitrogen, sulphur, and iron coordination and the peculiar morphology of PF-1000. Further, a single cell evaluation of a membrane electrode assembly based on PF-1000 as the cathode catalyst delivered a maximum power density of 193 mW cm(-2) at a cell temperature of 60 degrees C using Nafion as the proton conducting membrane.

}, issn = {2050-7488}, doi = {10.1039/c6ta00073h}, author = {Bhange, Siddheshwar N. and Unni, SreeKuttan M. and Kurungot, Sreekumar} } @article { ISI:000368754700011, title = {Pb2+-N bonding chemistry: recycling of polyaniline-pb nanocrystals waste for generating high-performance supercapacitor electrodes}, journal = {Journal of Physical Chemistry C}, volume = {120}, number = {2}, year = {2016}, month = {JAN}, pages = {911-918}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Understanding of Pb-N bonding chemistry is not only fundamentally important in the view of relativistic inert-pair effect but also is important for therapeutic as well as environmental applications. In the present study, an unusual reactivity of N-containing pi-conjugated polyaniline emeraldine base (EB) toward aqueous Pb2+ ions has been identified. In the course of sequestering Pb2+ ions by EB, cuboid-shaped nanocrystals were isolated. Synchrotron-based X-ray absorption near-edge structure and extended X-ray absorption fine structure techniques were employed to understand Pb-N bonding chemistry in EB-Pb nanocrystals. The adopted methodology of slow exposure of HCl vapor to EB-Pb nanomaterial facilitated the isolation of polyaniline emeraldine-salt (ES) with unique morphological patterns, porosity and electrical conductivity. The electrochemical device based on recycled ES showed high-capacitance value (similar to 606 F/g @1 A/g and similar to 663 F/g @10 mV/s), high-energy density (similar to 14.8 Wh/kg at power density of similar to 663 W/kg) and excellent-cycling stability (only similar to 15\% degradation after 1100 continued cycles at current density of 5 A/g). Notably, ES materials prepared directly from EB and upon exposing HNO3 vapor exhibited greatly inferior device performance.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.5b11217}, author = {Jha, Plawan Kumar and Singh, Santosh K. and Gatla, Suresh and Mathon, Olivier and Kurungot, Sreekumar and Ballav, Nirmalya} } @article { ISI:000368563000067, title = {Pt- and TCO-free flexible cathode for DSSC from highly conducting and flexible PEDOT paper prepared via in situ interfacial polymerization}, journal = {ACS Applied Materials \& Interfaces}, volume = {8}, number = {1}, year = {2016}, month = {JAN}, pages = {553-562}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Here, we report the preparation of a flexible, free-standing, Pt- and TCO-free counter electrode in dye-sensitized solar cell (DSSC)-derived from polyethylenedioxythiophene (PEDOT)-impregnated cellulose paper. The synthetic strategy of making the thin flexible PEDOT paper is simple and scalable, which can be achieved via in situ polymerization all through a roll coating technique. The very low sheet resistance (4 Omega/square) obtained from a film of 40 mu m thick PEDOT paper (PEDOT-p-5) is found to be superior to the conventional fluorine-doped tin oxide (FTO) substrate. The high conductivity (357 S/cm) displayed by PEDOT-p-5 is observed to be stable under ambient conditions as well as flexible and bending conditions. With all of these features in place, we could develop an efficient Pt- and TCO-free flexible counter electrode from PEDOT-p-5 for DSSC applications. The catalytic activity toward the tri-iodide reduction of the flexible electrode is analyzed by adopting various electrochemical methodologies. PEDOT-p-5 is found to display higher exchange current density (7.12 mA/cm(2)) and low charge transfer resistance (4.6 Omega) compared to the benchmark Pt-coated FTO glass (2.40 mA/cm(2) and 9.4 Omega, respectively). Further, a DSSC fabricated using PEDOT-p-5 as the counter electrode displays a comparable efficiency of 6.1\% relative to 6.9\% delivered by a system based on Pt/FTO as the counter electrode.

}, keywords = {counter electrode, dye-sensitized solar cell, flexible and thin devices, impedance analysis, interfacial polymerization, polyethylenedioxythiophene}, issn = {1944-8244}, doi = {10.1021/acsami.5b09579}, author = {Anothumakkool, Bihag and Agrawal, Ishita and Bhange, Siddheshwar N. and Soni, Roby and Game, Onkar S. and Ogale, Satishchandra B. and Kurungot, Sreekumar} } @article {45632, title = {Reduced graphene oxide modified electrodes for sensitive sensing of gliadin in food samples}, journal = {ACS Sensors}, volume = {1}, year = {2016}, month = {DEC}, pages = {1462-1470}, type = {Article}, abstract = {

Incidences of food allergies are on the rise, which can greatly affect the well-being of children as well as adults. Intolerance to gluten, a protein composite of gliadin and glutenin, present in wheat, barley, and rye and several cereals, can be the causative agent of celiac disease (CD) and other allergic reactions. A gluten-free diet has become essential for people affected by CD, and consequently, the amount of gluten in food products needs to be strictly controlled. In this paper, we report an electrochemical label-free immunosensor for ultrasensitive and specific detection of gliadin. The sensor takes advantage of the specific properties of porous reduced graphene oxide (prGO) covalently functionalized with anti-gliadin antibodies using 1-pyrenecarboxylic acid as linker molecule. Using differential pulse voltammetry (DPV) and [Fe(CN)6](3-/4-) as a redox probe, a decrease of current is linked to the presence of gliadin. The sensor achieved a detection limit of 1.2 ng mL(-1) over a 1.2-34 ng mL(-1) linear range with high selectivity. The advantages offered by this sensor are the possibility to regenerate the surface of the immunosensor, its rapid and ease of production, as well as applicability for the screening of gliadin concentrations in real food samples, as shown here.

}, keywords = {anti-gliadin antibody, food samples, gliadin, Immunosensor, Porous reduced graphene oxide}, issn = {2379-3694}, doi = {10.1021/acssensors.6b00608}, author = {Chekin, Fereshteh and Singh, Santosh K. and Vasilescu, Alina and Dhavale, Vishal M. and Kurungot, Sreekumar and Boukherroub, Rabah and Szunerits, Sabine} } @article {45638, title = {Strategic Preparation of Efficient and Durable NiCo Alloy Supported N-Doped Porous Graphene as an Oxygen Evolution Electrocatalyst: A Theoretical and Experimental Investigation}, journal = {Advanced Materials Interfaces}, volume = {3}, year = {2016}, month = {OCT }, pages = {1600532}, type = {Article}, abstract = {

Development of an efficient and durable water splitting electrocatalyst holds a great commitment for the future energy devices. The real application of oxygen evolution reaction (OER) catalysts mainly suffers from sluggish kinetics and high overpotential except for the Ir and Ru-based systems. However, the high cost and vulnerability of the Ir and Ru metals are the main hostiles to use them for marketization. Herein, a high-performance OER electrocatalyst consisting of NiCo alloy nanoparticles supported on high surface area N-doped porous graphene (NiCo/pNGr(75: 25)) is reported. The importance of the doped-N for achieving the uniform dispersion-cum-effective interaction of the size controlled NiCo alloy nanoparticles has been explicitly investigated by transmission electron microscopy, X-ray diffraction, X-ray photo electron spectroscopy, Raman, density functional theory (DFT) calculations, etc. The electrochemical analysis of NiCo/pNGr(75: 25) shows an overpotential of approximate to 260 mV at 10 mA cm(-2) with a smaller Tafel slope of approximate to 87 mV dec(-1) and long catalytic durability. DFT calculations are done to check the interaction between the NiCo alloy nanoparticles and the defective sites of pNGr and also with the doped-N, which could be attained for maintaining long catalytic durability. Furthermore, NiCo/pNGr(75: 25) is used as an OER catalyst to fabricate an electrolyzer, which works at very low potential of 1.5 V in 1 M KOH.

}, issn = {2196-7350}, doi = {10.1002/admi.201600532}, author = {Singh, Santosh K. and Kumar, Deepak and Dhavale, Vishal M. and Pal, Sourav and Kurungot, Sreekumar} } @article { ISI:000381436500019, title = {Understanding the electron transfer process in ZnO-naphthol azobenzoic acid composites from photophysical characterisation}, journal = {Physical Chemistry Chemical Physics}, volume = {18}, number = {32}, year = {2016}, month = {AUG}, pages = {22179-22187}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Semiconductor nanoparticles surface modified with organic molecules capable of visible light absorption and effectively transferring the electrons to the catalytic sites have the potential to be good photocatalysts. ZnO nanoparticles of size similar to 3 nm are grafted with two azonaphthols, one conjugated and the other non-conjugated. The photophysical properties of modified ZnO indicate an effective electron transfer from the conjugated azonaphthol to ZnO but not in the case of the non-conjugated molecule. It is also observed from lifetime studies that the conjugated molecule stabilises the defect sites on ZnO nanoparticles. It is possible that excited electrons from the conjugated molecule are transferred to specific defect sites in ZnO. This apparently does not occur in the non-conjugated molecule, bringing to focus the importance of the photophysical characteristics of organic modifiers in designing visible light active photocatalysts.

}, issn = {1463-9076}, doi = {10.1039/c6cp02908f}, author = {George, Leena and Kunhikannan, Athira K. and Illathvalappil, Rajith and Ottoor, Divya and Kurungot, Sreekumar and Devi, R. Nandini} } @article { ISI:000380045400014, title = {Unravelling the mechanism of electrochemical degradation of PANI in supercapacitors: achieving a feasible solution}, journal = {Chemelectrochem}, volume = {3}, number = {6}, year = {2016}, month = {JUN}, pages = {933-942}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Herein, we have investigated the mode of electrochemical degradation of polyaniline (PANI) when it was utilized as electrodes for supercapacitors. The PANI-based electrodes in supercapacitor devices were biased at a constant potential of 0.80 V, and the performance characteristics and property changes were carefully investigated as a function of the difference in the polarity of the electrodes. Subsequent to this, the analysis of the individual electrodes [positive (POS-PANI) and negative (NEG-PANI)] shows that the degradation mainly occurs at POS-PANI in comparison to NEG-PANI. Moreover, NEG-PANI retains a maximum capacitance of 510 Fg(-1), with a low charge-transfer resistance (R-CT) of 1.84 Omega and similar redox behavior in comparison to the fresh PANI (f-PANI). In contrast to this case, POS-PANI shows significant loss in capacitance (250 Fg(-1)) and increase in R-CT (3.5 Omega) with a disappearance of the characteristic redox behavior normally displayed by PANI. Furthermore, the drastic drop in the electrical conductivity for POS-PANI (1.2 Scm(-1)) compared to f-PANI (3.4 Scm(-1) and NEG-PANI (2.4 Scm(-1)) shows that the degradation of PANI occurs mainly at the anode (POS-PANI) and, thus, contributes to reduce the net performance of the cell. Hence, to ensure this potential-induced degradation of PANI in supercapacitors and also to promote the system stability, we made an asymmetric supercapacitor (ASC) by keeping PANI as a negative electrode and using carbon as a positive electrode. The derived system is found to display stable capacitance behavior before and after the potential application, in contrast to the ASC fabricated by using conventional method, that is, by keeping PANI as the positive electrode and carbon as the negative electrode. Furthermore, the durability analysis of the prototype solid-state ASC shows an enhanced durability of 27000 cycles with excellent columbic efficiency. The findings of the present study will be helpful in the development of highly stable supercapacitors and other similar energy systems when a material like PANI should be utilized for the electrode applications.

}, keywords = {asymmetric supercapacitors, cycle stability, electrochemical degradation, polarization, redox chemistry}, issn = {2196-0216}, doi = {10.1002/celc.201500502}, author = {Sekar, Pandiaraj and Anothumakkool, Bihag and Vijayakumar, Vidyanand and Lohgaonkar, Apurva and Kurungot, Sreekumar} } @article {45831, title = {Valorization of coffee bean waste: a coffee bean waste derived multifunctional catalyst for photocatalytic hydrogen production and electrocatalytic oxygen reduction reactions}, journal = {RSC Advances}, volume = {6}, year = {2016}, month = {AUG}, pages = {82103-82111}, type = {Article}, abstract = {

Here, we report the valorization of coffee bean waste (CBW) by producing nitrogen doped porous carbon (p-Cof) having both photocatalytic and electrocatalytic properties using a silica templating method. Morphological investigation of p-Cof reveals the presence of assemblies of highly porous flat carbon blocks. p-Cof exhibits a high surface area (1213 m(2) g(-1)) and a wide range of micro-and mesopores with good electrical conductivity. Along with this, the surface of p-Cof displays the presence of graphitic and pyridone-type nitrogen coordinations, which help p-Cof to perform as a multifunctional catalyst as revealed from its catalytic activities towards photocatalytic hydrogen production (PHP) and electrocatalytic oxygen reduction reactions. p-Cof produces 334 mu mol h(-1) g(-1) of hydrogen from water under visible light and 575 mmol h(-1) g(-1) of hydrogen under solar light irradiation with excellent stability. Along with this, p-Cof also displays improved oxygen reduction reaction (ORR) activity in alkaline medium. A better onset potential (0.91 V vs. RHE) and half-wave potential (0.75 V vs. RHE) are displayed by p-Cof compared to the catalyst derived from the simple annealing of CBW without employing the silica template. Along with the better electrochemical activity, p-Cof shows excellent ORR kinetics and electrochemical stability compared to the current state-of-the-art Pt/C.

}, issn = {2046-2069}, doi = {10.1039/c6ra14907c}, author = {Unni, SreeKuttan M. and George, Leena and Bhange, Siddheshwar N. and Devi, R. Nandini and Kurungot, Sreekumar} } @article { ISI:000368032100012, title = {Vitro and in silico antifungal efficacy of nitrogen- doped carbon nanohorn ( NCNH) against rhizoctonia solani}, journal = {Journal of Biomolecular Structure \& Dynamics}, volume = {34}, number = {1}, year = {2016}, month = {JAN}, pages = {152-162}, publisher = {TAYLOR \& FRANCIS INC}, type = {Article}, address = {530 WALNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA}, abstract = {

We have investigated in vitro antifungal efficiency of nitrogen-doped carbon nanohorn (NCNH) against Rhizoctonia solani (R. solani) plant pathogenic fungi. NCNH with size of 50-60nm and concentrations of 10, 50, 100, and 150gmL(-1) were used. The results showed that growth of fungi in the presence of NCNH was significantly (p\>.05) inhibited at 150gmL(-1) (85.13 +/-.97) after 72h. The results were validated through computational approaches. Molecular docking analysis of NCNH with endochitinase protein of R. solani was performed to validate the potential of antifungal activity of NCNH. Docking results showed different conformations of interaction of NCNH with endochitinase enzyme. The conformation with least binding energy -13.54kcal/mol was considered further. It is likely that NCNH interacts with the pathogens by mechanically wrapping, which may be one of the major toxicity actions of NCNH against R. solani. The analysis showed that NCNH might interwinds to endochitinase of R. solani leading to the deactivation of the enzyme. To best of our knowledge, this is the first report of antifungal efficacy of NCNH against R. solani and provides useful information about the application of NCNH in resisting crop disease.

}, keywords = {docking, endochitinase, nitrogen-doped carbon nanohorn, Rhizoctonia solani}, issn = {0739-1102}, doi = {10.1080/07391102.2015.1018841}, author = {Dharni, Seema and Sanchita and Unni, SreeKuttan M. and Kurungot, Sreekumar and Samad, Abdul and Sharma, Ashok and Patra, Dharani Dhar} } @article {43882, title = {Activity tuning of cobalt ferrite nanoparticles anchored on N-doped reduced graphene oxide as a potential oxygen reduction electrocatalyst by Zn substitution in the spinel matrix}, journal = {Chemistry Select}, volume = {2}, year = {2017}, month = {SEP}, pages = {7845-7853}, type = {Article}, abstract = {

Development of highly efficient and durable ORR catalysts by using non-platinum group metals (such as Co, Fe, Mn, and Zn) is a challenging task in the forward path towards the realization of low-cost energy devices in the commercial stream. The present work deals with an effective strategy wherein an efficient Pt-free electrocatalyst for oxygen reduction reaction (ORR) is prepared by stoichiometrically substituting some fraction of Fe with Zn in cobalt ferrite and anchoring these spinel nanoparticles on nitrogen doped reduced graphene oxide (N-rGO). Zn substitution is found to be significantly altering the ratio of Fe2+/Fe3+ in the cobalt ferrite nanocrystal system with a concomitant promotional influence on its electrocatalytic activity towards ORR. The nanoparticle composition with a Co, Fe and Zn molar ratio of 1.0:1.7:0.3, represented by the formula CoFe1.7Zn0.3O4(CFZn(0.3)), supported over N-rGO has shown 10 mV and 20 mV positive shift in the onset and half-wave potentials, respectively, for ORR in 0.1 M KOH in comparison to the nanoparticles of CoFe2O4 supported over N-rGO (CF/N-rGO). The optimum Zn substitution is found to be narrowing down the difference with the state-of-the-art Pt/C for ORR by 100 and 110 mV in terms of the onset and half-wave potentials, respectively. Most significantly, the homemade catalyst is found to be clearly outperforming the Pt catalyst in terms of the limiting current density and electrochemical durability.

}, keywords = {Carbon Nano-fiber, Cathod Catalyst, CoFe2O4, Evolution, Magnetic-properties, Membrane fuel- Cell, Metal-Air Batteries, N-doped graphene, Nanocrystalline, nanocrystals, oxygen reduction reaction, performance, Platinium, solvothermal synthesis, Zn substituted cobalt ferrite}, issn = {2365-6549}, doi = {10.1002/slct.201701684}, author = {Kashyap, Varchaswal and Singh, Santosh K. and Kurungot, Sreekumar} } @article {44175, title = {Chitosan intercalated metal organic gel as a green precursor of fe entrenched and fe distributed N-doped mesoporous graphitic carbon for oxygen reduction reaction}, journal = {Chemistryselect}, volume = {2}, year = {2017}, month = {SEP}, pages = {8762-8770}, type = {Article}, abstract = {

Herein, we present Metal-Organic Gel intercalated with chitosan, a {\textquoteleft}green{\textquoteright}{\textquoteright} precursor for the synthesis of intrinsic N-doped Fe entrenched (CHI-TMA-Fe-CW) and Fe distributed mesoporous graphitic carbon structures (CHI-TMA-Fe-CW-M1) with appreciable Oxygen Reduction Reaction (ORR) activity in alkaline medium. Modulation of the synthetic protocol as a function of reaction kinetics and gelation time while maintaining identical pyrolysis conditions (900 degrees C, flowing N-2 atmosphere) improves the microstructure, surface area and Fe distribution of the graphitic structures (CHI-TMA-Fe-CW-M1). CHI-TMA-Fe-CW has a Fe entrenched graphitic nanocapsule like morphology while Fe distributed mesoporous graphitic carbon sheets, with a specific surface area value of 565 m(2) g(-1) obtained by modulating the synthesis chemistry in CHI-TMA-Fe-CW-M1. The higher percentage of graphitic N in CHI-TMA-Fe-CW-M1 apparent from the XPS data validate that the modified synthetic method favours creation of more graphitic N sites contributing for better catalytic performance. CHI-TMA-Fe-CW-M1 catalyst exhibited comparable electrocatalytic activity with that of the commercially available Pt/C via an efficient four-electron-dominant ORR pathway with a positive onset potential value of 0.925 V vs RHE. Good durability of CHI-TMA-Fe-CW-M1 after 5000 cycles further confirm the prospects of MOG-chitosan and the feasibility to be used as a potential catalyst for ORR.

}, keywords = {electrocatalyst, fuel cell, Metal-Organic-Gel, oxygen reduction reaction}, issn = {2365-6549}, doi = {10.1002/slct.201701416}, author = {Shijina, Kottarathil and Illathvalappil, Rajith and Kurungot, Sreekumar and Nair, Balagopal N. and Mohamed, A. Peer and Yamaguchi, Takeo and Anilkumar, Gopinathan M. and Hareesh, U. S. and Sailaja, G. S.} } @article {43791, title = {On demand electrochemical release of drugs from porous reduced graphene oxide modified flexible electrodes}, journal = {Journal of Materials Chemistry B}, volume = {5}, year = {2017}, month = {AUG}, pages = {6557-6565}, type = {Article}, abstract = {Despite the advantages of an electrochemical control for drug release, only a handful of electrochemical-based release systems have been developed so far. We report herein on the development of an electrochemically activatable platform for on-demand delivery of drugs. It is based on flexible gold thin film electrodes coated with porous reduced graphene oxide (prGO) nanosheets onto which the drug of interest has been integrated beforehand. Two different drugs are investigated here: ondansetron hydrochloride (ODS), a selective 5-HT3 receptor antagonist used for preventing nausea and vomiting caused by chemotherapy and radiotherapy, and ampicillin (AMP), an antibiotic to prevent and treat a number of bacterial infections such as respiratory tract infections, urinary tract infections, and meningitis. In the case of ODS, application of a negative potential bias of -0.8 V results in a sustained slow ODS release with an ODS flux of 47 mu g cm(-2) h(-1). In the case of AMP, we show that polyethyleneimine modified prGO (prGO/PEI) is an extremely efficient matrix. Upon the application of +0.8 V, 24\% of AMP could be released from the electrical interface in a time span of 2 h. The released AMP kept its antibacterial activity as demonstrated by antimicrobial tests. These examples illustrate the major benefits of the developed approach for biomedical applications.}, doi = {10.1039/c7tb00687j}, author = {Boulahneche, Samia and Jijie, Roxana and Barras, Alexandre and Chekin, Fereshteh and Singh, Santosh K. and Bouckaert, Julie and Medjram, Mohamed Salah and Kurungot, Sreekumar and Boukherroub, Rabah and Szunerits, Sabine} } @article {43846, title = {Enhanced proton conduction by post-synthetic covalent modification in a porous covalent framework}, journal = {Journal of Materials Chemistry A}, volume = {5}, year = {2017}, month = {JUL}, pages = {13659-13664}, type = {Article}, abstract = {A highly chemically stable porous covalent framework (PCF-1) based on ether linkages has been synthesized, which exhibits no loss up to similar to 500 degrees C along with retention of integrity under acidic, basic and oxidative reagent conditions. Owing to its thermal and chemical stability, post-synthetic covalent modification was executed for the introduction of pendant sulphonic acid (-SO3H) groups. The covalently modified compound (PCF-1-SO3H) presents a remarkably high conductivity (ca. 0.026 S cm(-1)), with an similar to 130 fold enhancement in proton conductivity over the parent compound. This value is comparable with those of commercially used Nafion-based proton conducting materials and stands as the highest known value in the regime of post-synthetically modified porous organic frameworks. It is noteworthy to mention that PCF-1 is stable in both acidic and alkaline media, which is not commonly observed for most of the porous materials trialed as proton conducting materials, including metal organic frameworks.}, doi = {10.1039/c7ta00964j}, author = {Samanta, Partha and Desai, Aamod V. and Anothumakkool, Bihag and Shirolkar, Mandar M. and Karmakar, Avishek and Kurungot, Sreekumar and Ghosh, Sujit K.} } @article {45760, title = {Grafoil-scotch tape-derived highly conducting flexible substrate and its application as a supercapacitor electrode}, journal = {Nanoscale}, volume = {9}, year = {2017}, month = {MAR }, pages = {3593-3600}, type = {Article}, abstract = {

Development of flexible supercapacitors is limited by the availability of flexible and durable conducting substrates; a conducting and cheap substrate for the active material deposition is essential for breakthrough progress in this direction. In this report, a highly flexible, conducting, and cheap substrate is prepared by simple stick and peel-off method involving Scotch tape and Grafoil. A Grafoil-Scotch tape derived flexible substrate exhibits a sheet resistance of 7 Omega square(-1) along with a high degree of flexibility and durability. Moreover, its properties are further enhanced by the anodization in order to increase the hydrophilicity and surface area. The substrate is highly thin with a thickness of just 74 mu m. Its practical utility has been demonstrated by electrodepositing MnO2 as an active material and, thereafter, fabricating a solid-state flexible supercapacitor. The fabricated device exhibits high capacitance retention under bent (99\%) and twisted (98\%) conditions along with a low ESR of 7 Omega.

}, issn = {2040-3364}, doi = {10.1039/c7nr00281e}, author = {Soni, Roby and Raveendran, Alka and Kurungot, Sreekumar} } @article {44130, title = {High-level supercapacitive performance of chemically reduced graphene oxide}, journal = {Chem}, volume = {3}, year = {2017}, month = {NOV}, pages = {846-860}, type = {Article}, abstract = {Reduction of graphene oxide (GO) is an important process because it holds promise for the production of reduced graphene oxide (rGO) with physicochemical properties similar to those of pristine graphene. In conventional chemical reduction, strong reducing agents, such as sodium borohydride and hydrazine, cannot be recycled. Also, fast reaction kinetics bring an imbalance in the desirable properties of rGO. Here, we present one-pot chemical reduction of GO in aqueous medium by an unconventional mild reducing agent (FeCl2/HCl) where rGOis isolated as the precipitate and the reducing agent is recycled upon simple treatment of the filtrate with HCl. The fabricated all-solid-state supercapacitors of as-synthesized rGO exhibited significantly higher specific capacitance than those obtained with rGO derived from conventional reducing agents. The cycling stability of the all-solid-state supercapacitor (> 80\% retention of capacitance beyond 100,000 continued cycles) and its flexibility (> 500 bending cycles) were remarkable. Use of commercially available organic electrolyte further boosted the supercapacitor performance.}, doi = {10.1016/j.chempr.2017.08.011}, author = {Jha, Plawan Kumar and Singh, Santosh Kumar and Kumar, Vikash and Rana, Shammi and Kurungot, Sreekumar and Ballav, Nirmalya} } @article {43772, title = {Magnetic reduced graphene oxide loaded hydrogels: highly versatile and efficient adsorbents for dyes and selective Cr(VI) ions removal}, journal = {Journal of Colloid and Interface Science}, volume = {507}, year = {2017}, month = {DEC}, pages = {360-369}, type = {Article}, abstract = {The formation of composites of reduced graphene oxide (rGO) and magnetic nanoparticles (MP) has flourished in recent years as they combine the advantages of both nanomaterials. Most of these composite materials are prepared by in situ formation of MP onto rGO or by the post-adsorption onto rGO. We report here on a simple and highly controlled method for the fabrication of different magnetic 3D rGO-loaded hydrogels. Cellulose bound magnetic nanoparticles (MP@cellulose) were synthesized by chemical co-precipitation and loaded together with rGO into poly(ethylene glycol) dimethacrylate based hydrogels during their fabrication using photo-polymerization. The magnetic rGO-loaded hydrogels proved to be highly adaptable to different applications. The as-formed composites allowed for efficient dye removal with an adsorption capacity of 111.9 +/- 4 mg g(-1) in the case of methylene blue (MB). Integration of poly(ethyleneimine) (PEI) allowed for the selective capturing of Cr6+ ions with an adsorption capacity of 313 12 mg g-1. Most importantly, independent of the application, the magnetic rGO-loaded hydrogel can be regenerated without loss of its adsorption capacity. (C) 2017 Elsevier Inc. All rights reserved.}, doi = {10.1016/j.jcis.2017.07.075}, author = {Halouane, Fatima and Oz, Yavuz and Meziane, Dalila and Barras, Alexandre and Juraszek, Jean and Singh, Santosh K. and Kurungot, Sreekumar and Shaw, Pankaj K. and Sanyal, Rana and Boukherroub, Rabah and Sanyal, Amitav and Szunerits, Sabine} } @article {43824, title = {Nanocrystalline Fe-Fe2O3 particledeposited N-doped graphene as an activity-modulated Pt-free electrocatalyst for oxygen reduction reaction}, journal = {Nanoscale}, volume = {9}, year = {2017}, month = {SEP}, pages = {13341-13342}, type = {Article}, issn = { 2040-3364}, doi = {10.1039/c7nr90179h}, author = {Dhavale, Vishal M. and Singh, Santosh K. and Nadeema, Ayasha and Gaikwad, Sachin S. and Kurungot, Sreekumar} } @article {43844, title = {Nitrogen-doped graphene anchored with mixed growth patterns of CuPt alloy nanoparticles as a highly efficient and durable electrocatalyst for the oxygen reduction reaction in an alkaline medium}, journal = {Nanoscale}, volume = {9}, year = {2017}, month = {JUL}, pages = {9009-9017}, type = {Article}, abstract = {

A highly active and durable CuPt alloy catalyst with trigonal bipyramidal and truncated cube-type mixed morphologies, anchored on the nitrogen-doped graphene (NGr) surface (CuPt-TBTC/NGr), was prepared by a simple and fast method. The obtained CuPt alloy showed improved oxygen reduction reaction (ORR) activity, with a 30 mV positive shift in the half-wave potential value, as compared to the state-of-the-art Pt/C catalyst in a 0.1 M KOH solution. The CuPt alloy with the trigonal bipyramidal morphology possesses porous type inter-connected sides, which help to achieve improved mass transport of oxygen during the ORR. The exposure of the (111) plane of the CuPt alloy further improved the catalytic activity towards the dioxygen reduction in alkaline media. The ORR activity of the NGr-supported CuPt alloy was found to be dependent on the reaction time, and improved activity was obtained on the material derived at a reaction time of 90 min (CuPt-TBTC/NGr-90). The material synthesized at a lower or higher reaction time than 90 min resulted in a partially formed trigonal bipyramidal morphology with more truncated cubes or agglomerated trigonal bipyramidal and truncated cubes with closed type structures, respectively. Along with the high intrinsic ORR activity, CuPt-TBTC/NGr-90 displayed excellent electrochemical stability. Even after repeated 1000 potential cycling in a window ranging from 0.10 to 1.0 V (vs. RHE), the system clearly outperformed the state-of-the-art Pt/C catalyst with 15 and 60 mV positive shifts in the onset and half-wave potentials, respectively. CuPt-TBTC/NGr-90 also exhibited 2.1 times higher mass activity and 2.2 times higher specific activity, compared to Pt/C at 0.90 V (vs. RHE). Finally, a zinc-air battery fabricated with the alloy catalyst as the air electrode displayed a peak power density of 300 mW cm(-2), which is much higher than the peak power density of 253 mW cm(-2) obtained for the state-of-the-art Pt/C catalyst as the air electrode.

}, doi = {10.1039/c7nr00697g}, author = {Illathvalappil, Rajith and Dhavale, Vishal M. and Bhange, Siddheshwar N. and Kurungot, Sreekumar} } @article {44172, title = {Nitrogen-doped graphene with a three-dimensional architecture assisted by carbon nitride tetrapods as an efficient metal-free electrocatalyst for hydrogen evolution}, journal = {Chemelectrochem}, volume = {4}, year = {2017}, month = {OCT}, pages = {2643-2652}, type = {Article}, abstract = {Current polymer membrane-based electrolyzers use Pt as a cathode catalyst for efficient reduction of water. The high cost of Pt-based catalysts forces researchers to develop alternative electrocatalysts. Here, a simple strategy has been proposed to synthesize a metal-free electrocatalyst for the hydrogen evolution reaction (HER) by high-temperature annealing of graphene oxide-coated melamine foam. The prepared catalyst possesses both structural and functional advantages with its three-dimensional (3D) interconnected arms of carbon nitride (CNx) backbone wrapped with nitrogen-doped graphene (N-RGO) sheets (CNx@N-RGO). CNx@N-RGO faces only a 193 mV overpotential to achieve a current density of 10mAcm(-2), which is far superior to the previously reported Pt-free systems. Along with the high exchange current density 34.7 x 10(-6)A cm(-2) and low Tafel slope of 54 mV dec(-1), CNx@N-RGO follows a Volmer-Heyrovsky mechanism for the HER. DFT calculations show that the synergy between CNx and N-RGO facilitates good electrical coupling between the two moieties and provides optimal binding to H+ ions on the catalyst that, in turn, results in efficient reduction of hydrogen ions.}, keywords = {carbon nitride, Density functional theory, electrocatalyst, hydrogen evolution reaction, nitrogen doped graphene}, issn = {2196-0216}, doi = {10.1002/celc.201700479}, author = {Gangadharan, Pranav K. and Unni, SreeKuttan M. and Kumar, Nandha and Ghosh, Prasenjit and Kurungot, Sreekumar} } @article {43870, title = {NiZn double hydroxide nanosheet-anchored nitrogen-doped graphene enriched with the gamma-NiOOH phase as an activity modulated water oxidation electrocatalyst}, journal = {Nanoscale}, volume = {9}, year = {2017}, month = {SEP}, pages = {12590-12600}, type = {Journal Article}, chapter = {12590-12600}, abstract = {

Herein, we report a facile solvothermal process to synthesize an active electrocatalyst for the oxygen evolution reaction (OER) in an alkaline medium by anchoring nanosheets of a NiZn double hydroxide over nitrogen doped reduced graphene oxide after enriching the system with the γ-NiOOH phase. This catalyst possesses a thin, porous and open layered structure, which makes the system more efficient and accessible for a better electrochemical water oxidation reaction. Moreover, we experimentally demonstrated that incorporation of Zn via a single-step solvothermal method provides an easy approach to obtain plenty of exposed γ-NiOOH phases to make the system more viable for OER with a small overpotential of 290 mV at 10 mA cm-2 and a Tafel slope of 44 mV per decade. In addition to this, the oxophilic nature of Zn in the (Zn)Ni-LDH/N-rGO catalyst helps to improve the long-term stability of the whole system. The obtained results open up possibilities for the design of future robust OER electrocatalysts by the use of very cheap and abundant materials like Ni and Zn in place of expensive Ir and Ru in the present commercial electrocatalysts.

}, keywords = {catalysis, Efficient Electrocatalyst, kinetics, Metal, Nickel-Hydroxide, oxide, Oxygen Evolution Reaction, performance, XPS Spectra, zinc}, issn = {2040-3364}, doi = {10.1039/c7nr02225e}, author = {Nadeema, Ayasha and Dhavale, Vishal M. and Kurungot, Sreekumar} } @article {44129, title = { Porous reduced graphene oxide modified electrodes for the analysis of protein aggregation. part 1: lysozyme aggregation at pH 2 and 7.4}, journal = {Electrochimica Acta}, volume = {254}, year = {2017}, month = {NOV}, pages = {375-383}, type = {Article}, abstract = {Protein instability due to misfolding and aggregation is of big concern for protein based therapeutics because it impacts the bioavailability and immunogenicity of such drugs. The development of simple and cost-effective methods for the analysis of pharmaceutical formulations, indicating the presence or absence of protein aggregates, is consequently of high importance. This work proposes a novel electrochemical interface based on porous reduced graphene oxide coated glassy carbon electrode (GC/prGO) allowing for the early and sensitive identification of protein aggregation by following the change in the oxidative current of the proteins. The novelty of this work lies in the exploration of the ability of GC/prGO interfaces to capture different aggregation behaviors. Lysozyme is used as a model to follow by electrochemistry its aggregation at two pH values, pH 2 and pH 7.4, leading to the formation of amyloid and amorphous aggregates, respectively. Comparing the oxidation peak of lysozyme by differential pulse voltammetry (DPV) for different electrode architectures allowed validating the higher sensitivity of the GC/prGO interface versus bare glassy electrodes or electrodes coated with non-porous reduced graphene oxide. Parallel experiments were performed by fluorescence with thioflavin T, size exclusion chromatography and Atomic Force Microscopy (AFM) imaging. These tests further highlighted the usefulness of GC/prGO electrode to visualize in a fast and reliable manner the changes in the protein structure and the differences between the processes occurring at pH 2 and pH 7.4. In particular, the ability to emphasize changes related to the first steps in aggregation that could be indicative of the aggregation course, recommend the GC/prGO electrode in combination with DPV as a new analytical tool for aggregation studies of biopharmaceuticals. Part 2 of this work will demonstrate later the utility of this approach for the analysis of a fast acting injectable human insulin formulation, Humulin R, used for diabetes treatment as well as for calcitonin. (C) 2017 Elsevier Ltd. All rights reserved.}, doi = {10.1016/j.electacta.2017.09.083}, author = {Vasilescu, Alina and Boulahneche, Samia and Chekin, Fereshteh and Gaspar, Szilveszter and Medjram, Mohamed Salah and Diagne, Abdou Aziz and Singh, Santosh K. and Kurungot, Sreekumar and Boukherroub, Rabah and Szunerits, Sabine} } @article {43654, title = {Proton conduction in a hydrogen-bonded complex of copper(II)-bipyridine glycoluril nitrate}, journal = {Dalton Transactions}, volume = {46}, year = {2017}, month = {JUN}, pages = {6968-6974}, abstract = {Bipyridine glycoluril (BPG), a urea-fused bipyridine tecton, forms a square-pyramidal secondary building unit with copper(II) which further self-assembles to give a porous hydrogen-bonded complex. This complex displays a high proton conductivity of 4.45 x 10(-3) S cm(-1) at 90 degrees C and 95\% relative humidity (RH). Chains consisting of coordinated water, solvent water and nitrate anions embedded in the complex are responsible for high proton conduction. The proton conduction pathway was corroborated by ab initio electronic structure calculations with molecular dynamics (MD) simulations using the Nudged Elastic Band (NEB) method. The theoretical activation energy estimated to be 0.18 eV is in close agreement with the experimental value of 0.15 eV which evidences a Grotthuss proton hopping mechanism. We thus demonstrate that the hydrogen-bonded complex encapsulating appropriate counter ions, coordinated water and solvent water molecules exhibts superprotonic conductivity.}, doi = {10.1039/c7dt00425g}, author = {Tayade, Sakharam B. and Dhavale, Vishal M. and Kumbhar, Avinash S. and Kurungot, Sreekumar and Loennecke, Peter and Hey-Hawkins, Evamarie and Pujari, Bhalchandra} } @article {44144, title = {Selective isolation and eradication of E. coli associated with urinary tract infections using anti-fimbrial modified magnetic reduced graphene oxide nanoheaters}, journal = {Journal of Materials Chemistry B}, volume = {5}, year = {2017}, month = {OCT}, pages = { 8133-8142}, type = {Article}, abstract = {The fast and efficient elimination of pathogenic bacteria from water, food or biological samples such as blood remains a challenging task. Magnetic isolation of bacteria from complex media holds particular promise for water disinfection and other biotechnological applications employing bacteria. When it comes to infectious diseases such as urinary tract infections, the selective removal of the pathogenic species in complex media such as human serum is also of importance. This issue can only be accomplished by adding pathogen specific targeting sites onto the magnetic nanostructures. In this work, we investigate the potential of 2-nitrodopamine modified magnetic particles anchored on reduced graphene oxide (rGO) nanocomposites for rapid capture and efficient elimination of E. coli associated with urinary tract infections (UTIs) from water and serum samples. An optimized magnetic nanocarrier achieves a 99.9\% capture efficiency even at E. coli concentrations of 1 x 10(1) cfu mL(-1) in 30 min. In addition, functionalization of the nanostructures with poly(ethylene glycol) modified pyrene units and anti-fimbrial E. coli antibodies allowed specific elimination of E. coli UTI89 from serum samples. Irradiation of the E. coli loaded nanocomposite with a near-infrared laser results in the total ablation of the captured pathogens. This method can be flexibly modified for any other pathogenic bacteria, depending on the antibodies used, and might be an interesting alternative material for a magnetic-based body fluid purification approach.}, doi = {10.1039/c7tb01890h}, author = {Halouane, Fatima and Jijie, Roxana and Meziane, Dalila and Li, Chengnan and Singh, Santosh K. and Bouckaert, Julie and Jurazek, Jean and Kurungot, Sreekumar and Barras, Alexandre and Li, Musen and Boukherroub, Rabah and Szunerits, Sabine} } @article {45723, title = {Single cell fabrication towards the realistic evaluation of a CNT-strung ZIF-derived electrocatalyst as a cathode material in alkaline fuel cells and metal-air batteries}, journal = {ChemElectroChem}, volume = {4}, year = {2017}, month = {NOV}, pages = {2928-2933}, type = {Article}, abstract = {

The development of an electrocatalyst possessing all the vital requisites of an ideal electrode material, such as high porosity, high conductivity, and high intrinsic electrochemical activity, holds a decisive key in determining the activity of the triplephase boundary in many energy devices like fuel cells and metal-air battery systems. In the present work, highly porous cobalt-based ZIFs are strung along the highly conducive CNT backbone by using a simple one-pot technique at room temperature, which is then utilized to derive a porous, corrosion-resistant, Co nanoparticle-embedded electrocatalyst. Herein, for the first time, the single cell performance of the Co-ZIF-67-derived electrocatalyst has been evaluated by fabricating membrane electrode assemblies of alkaline exchange membrane fuel cell (AEMFC) and zinc-air battery (ZAB) systems. A maximum power density of 296 mW/cm(2) (vs. 317 mW/cm(2) for 40 wt.\% Pt/C) and 60 mW/cm(2) (vs. 64 mW/cm(2) for 40 wt.\% Pt/C) in the single cells of ZAB and AEMFC systems, respectively, establishes the practical proficiency of the homemade electrocatalyst for cathode applications during realistic system-level validations.

}, keywords = {Batteries, Carbon nanotubes, Composite materials, fuel cells, metal-organic frameworks}, issn = {2196-0216}, doi = {10.1002/celc.201700562}, author = {Aiyappa, Harshitha Barike and Bhange, Siddheshwar N. and Sivasankaran, Vijitha P. and Kurungot, Sreekumar} } @article {43793, title = {Ultrahigh ionic conduction in water-stable close-packed metal-carbonate frameworks}, journal = {Inorganic Chemistry}, volume = {56}, year = {2017}, month = {AUG}, pages = {9710-9715}, type = {Article}, abstract = {Utilization of the robust metal-carbonate backbone in a series of water-stable, anionic frameworks has been harnessed for the function of highly efficient solid-state ion conduction. The compact organization of hydrophilic guest ions facilitates water-assisted ion-conduction in all the compounds. The dense packing of the compounds imparts high ion-conducting ability and minimizes the possibility of fuel crossover, making this approach promising for design and development of compounds as potential components of energy devices. This work presents the first report of evaluating ion-conduction in a purely metal-carbonate framework, which exhibits high ion-conductivity on the order of 10(-2) S cm(-1) along with very low activation energy, which is comparable to highly conducting well-known crystalline coordination polymers or commercialized organic polymers like Nafion.}, doi = {10.1021/acs.inorgchem.7b01217}, author = {Manna, Biplab and Desai, Aamod V. and Illathvalappil, Rajith and Gupta, Kriti and Sen, Arunabha and Kurungot, Sreekumar and Ghosh, Sujit K.} } @article {45421, title = {Convergent covalent organic framework thin sheets as flexible supercapacitor electrodes}, journal = {ACS Applied Material \& Interfaces}, volume = {10}, year = {2018}, month = {AUG}, pages = {28139-28146}, type = {Article}, abstract = {Flexible supercapacitors in modern electronic equipment require light-weight electrodes, which have a high surface area, precisely integrated redox moieties, and mechanically strong flexible free-standing nature. However, the incorporation of the aforementioned properties into a single electrode remains a great task. Herein, we could overcome these challenges by a facile and scalable synthesis of the convergent covalent organic framework (COF) free-standing flexible thin sheets through solid-state molecular baking strategy. Here, redox-active anthraquinone (Dq) and pi-electron-rich anthracene (Da) are judiciously selected as two different linkers in a beta-ketoenamine-linked two-dimensional (2D) COF. As a result of precisely integrated anthraquinone moieties, COF thin sheet exhibits redox activity. Meanwhile, pi-electron-rich anthracene linker assists to improve the mechanical property of the free-standing thin sheet through the enhancement of noncovalent interaction between crystallites. This binder-free strategy offers the togetherness of crystallinity and flexibility in 2D COF thin sheets. Also, the synthesized porous crystalline convergent COF thin sheets are benefited with crack-free uniform surface and light-weight nature. Further, to demonstrate the practical utility of the material as an electrode in energy-storage systems, we fabricated a solid-state symmetrical flexible COF supercapacitor device using a GRAFOIL peeled carbon tape as the current collector.}, doi = {10.1021/acsami.8b10486}, author = {Khayum, Abdul M. and Vijayakumar, Vidyanand and Karak, Suvendu and Kandambeth, Sharath and Bhadra, Mohitosh and Suresh, Karthika and Acharambath, Nikhil and Kurungot, Sreekumar and Banerjee, Rahul} } @article {45391, title = {Interlayer hydrogen-bonded covalent organic frameworks as high-performance supercapacitors}, journal = {Journal of the American Chemical Society}, volume = {140}, year = {2018}, month = {SEP}, pages = { 10941-10945}, type = {Article}, abstract = {Covalent organic frameworks (COFs) have emerged as promising electrode materials in supercapacitors (SCs). However, their insoluble powder-like nature, poor capacitive performance in pristine form, integrated with inferior electrochemical stability is a primary concern for their long-term use in electrochemical devices. Keeping this in perspective, herein we report a redox active and hydrogen bonded COF with ultrahigh stability in conc. H2SO4 (18 M), conc. HCl (12 M) and NaOH (9 M). The as-synthesized COF fabricated as thin sheets were efficiently employed as a free-standing supercapacitor electrode material using 3 M aq. H2SO4 as an electrolyte. Moreover, the pristine COF sheet showcased outstanding areal capacitance 1600 mF cm(-2) (gravimetric 169 F g(-1)) and excellent cyclic stability (>100 000) without compromising its capacitive performance or Coulombic efficiency. Moreover, as a proof-of-concept, a solid-state supercapacitor device was also assembled and subsequently tested.}, doi = {10.1021/jacs.8b06460}, author = {Halder, Arjun and Ghosh, Meena and Khayum, Abdul M. and Bera, Saibal and Addicoat, Matthew and Sasmal, Himadri Sekhar and Karak, Suvendu and Kurungot, Sreekumar and Banerjee, Rahul} } @article {44511, title = {Iron Catalyzed Hydroformylation of Alkenes under Mild Conditions: Evidence of an Fe(II) Catalyzed Process}, journal = {Journal of the American Chemical Society}, volume = {140}, year = {2018}, month = {MAR }, pages = {4430-4439}, abstract = {

Earth abundant, first row transition metals offer a cheap and sustainable alternative to the rare and precious metals. However, utilization of first row metals in catalysis requires harsh reaction conditions, suffers from limited activity, and fails to tolerate functional groups. Reported here is a highly efficient iron catalyzed hydroformylation of alkenes under mild conditions. This protocol operates at 10-30 bar syngas pressure below 100 degrees C, utilizes readily available ligands, and applies to an array of olefins. Thus, the iron precursor [HFe(CO)(4)](-)[Ph3PNPPh3](+) (1) in the presence of triphenyl phosphine catalyzes the hydroformylation of 1-hexene (S2), 1-octene (S1), 1-decene (S3), 1-dodecene (S4), 1-octadecene (S5), trimethoxy(vinyl)silane (S6), trimethyl(vinyl)silane (S7), cardanol (S8), 2,3-dihydrofuran (S9), allyl malonic acid (S10), styrene (S11), 4-methylstyrene (S12), 4-iBu-styrene (S13), 4-tBu-styrene (S14), 4-methoxy styrene (S15), 4-acetoxy styrene (S16), 4-bromo styrene (S17), 4-chloro styrene (S18), 4-vinylbenzonitrile (S19), 4-vinylbenzoic acid (S20), and allyl benzene (S21) to corresponding aldehydes in good to excellent yields. Both electron donating and electron withdrawing substituents could be tolerated and excellent conversions were obtained for S11-S20. Remarkably, the addition of 1 mol \% acetic acid promotes the reaction to completion within 16-24 h. Detailed mechanistic investigations revealed in situ formation of an iron-dihydride complex [H2Fe(CO)(2)(PPh3)(2)] (A) as an active catalytic species. This finding was further supported by cyclic voltammetry investigations and intermediacy of an Fe(0)-Fe(II) species was established. Combined experimental and computational investigations support the existence of an iron-dihydride as the catalyst resting state, which then follows a Fe(II) based catalytic cycle to produce aldehyde.

}, issn = {0002-7863}, doi = {10.1021/jacs.8b01286}, author = {Pandey, Swechchha and Raj, K. Vipin and Shinde, Dinesh R. and Vanka, Kumar and Kashyap, Varchaswal and Kurungot, Sreekumar and Vinod, C. P. and Chikkali, Samir H.} } @article {45392, title = {Melamine formaldehyde-metal organic gel interpenetrating polymer network derived intrinsic Fe-N-doped porous graphitic carbon electrocatalysts for oxygen reduction reaction}, journal = {New Journal of Chemistry }, volume = {42}, year = {2018}, month = {DEC}, pages = {18690-18701}, type = {Article}, abstract = {Fe, N doped porous graphitic carbon electrocatalyst (Fe-MOG-MF-C), obtained by pyrolysis of an Interpenetrating Polymer Network (IPN) comprised of melamine formaldehyde (MF as hard segment) and Metal-Organic Gel (MOG as soft segment), exhibited significant Oxygen Reduction Reaction (ORR) activity in alkaline medium. BET surface area analysis of Fe-MOG-MF-C showed high surface area (821 m(2) g(-1)), while TEM, Raman and XPS results confirmed Fe and N co-doping. Furthermore, a modulated porous morphology with a higher degree of surface area (950 m(2) g(-1)) has been accomplished for the system (Fe-MOG-MFN-C) when aided by a sublimable porogen, such as naphthalene. XPS results further demonstrated that these systems exhibited a better degree of distribution of graphitic N and an onset potential value of 0.91 V vs. RHE in 0.1 M KOH solution following an efficient four-electron ORR pathway. The electrocatalytic activity of Fe-MOG-MFN-C is superior to that of Fe-MOG-MF-C by virtue of its higher graphitic N content and surface area. Thus, the study presents a new class of IPN derived MF-MOG nanocomposites with the potential to generate extended versions of in situ Fe-N doped porous graphitic carbon structures with superior ORR activity.}, issn = {1144-0546}, doi = {10.1039/c8nj03170c}, author = {Shijina, Kottarathil and llathvalappil, Rajith and Sumitha, N. S. and Sailaja, G. S. and Kurungot, Sreekumar and Nair, Balagopal N. and Mohamed, A. Peer and Anilkumar, Gopinathan M. and Yamaguchig, Takeo and Hareesh, U. S.} } @article {44637, title = {Morphological ensembles of N-doped porous carbon derived from ZIF-8/Fe-graphene nanocomposites: processing and electrocatalytic studies}, journal = {ChemistrySelect}, volume = {3}, year = {2018}, month = {AUG}, pages = {8688-8697}, abstract = {

Engineering the active site density of porous carbon catalysts for enhanced electrocatalytic activity is the current focus in the quest for economically viable fuel cells. Herein, we synthesise ZIF-8/Fe-graphene composites for the formation of N and Fe co-doped carbon with diverse morphologies ranging from tubes and sheets to frameworks of carbon. A synthetic strategy involving the one pot synthesis of ZIF-8 based composites is accomplished by the reaction of 2-methylimidazole with mixed Zn/Fe salt solution containing graphene dispersions. The high temperature heat treatment of this precursor mix yielded micro-meso porous architectures of N, Fe co-doped carbon with dispersions of Fe/Fe3C. An onset potential value of 0.95 V and a half-wave potential of 0.82 V coupled with excellent durability and stability in alkaline medium indicated improved electrocatalytic performances over its commercial Pt/C counterpart. The appreciable electrocatalytic properties of the synthesized carbon are attributed to its morphological diversity, hybrid structure, high N doping and its heteroporous characteristics. The dispersed Fe/Fe3C and FeNx sites facilitated enhanced oxygen adsorption and the graphene inclusions in the composite provided retention of high nitrogen contents.

}, keywords = {electrocatalyst, fuel cell, N- Fe co-doped carbon, oxygen reduction reaction, ZIF-8}, issn = {2365-6549}, doi = {10.1002/slct.201801419}, author = {Thomas, Minju and Illathvalappil, Rajith and Kurungot, Sreekumar and Nair, Balagopal N. and Mohamed, A. Peer and Anilkumar, Gopinathan M. and Yamaguchi, Takeo and Hareesh, U. S.} } @article {44185, title = {Naphthalene diimide copolymers by direct arylation polycondensation as highly stable supercapacitor electrode materials}, journal = {Macromolecules}, volume = {51}, year = {2018}, month = {FEB}, pages = {954-965}, type = {Article}, abstract = {

Conjugated donor-acceptor copolymers based on naphthalene diimide (NDI) as acceptor and thiopheneterminated oligophenylenevinylene as donor moieties (P-1 and P-2, respectively) were synthesized using the direct (hetero) arylation (DHAP) polymerization route. Nitrile groups were introduced at the vinylene linkage in one copolymer (P-2) to fine-tune its electrochemical properties. Both polymers show) pi-pi* transition in the 300-480 nm region and intramolecular charge transfer (ICT) from thiophene to NDI in the 500-800 nm region in the absorption spectra. P-2 exhibits a blue-shifted intramolecular charge transfer (ICT) band in the absorption spectrum as well as a lower reduction potential in the cyclic voltammogram compared to the analogous polymer without the nitrile substitution (P-1). The two polymers were evaluated as type III supercapacitor materials by preparing composite electrodes with carbon nanotubes (CNTs) and employing 0.5 M H2SO4 as the electrolyte. Their performance was compared with that of P(NDI2OD-T2) as a reference polymer. The polymer P-2 based supercapacitor exhibits a specific capacitance of 124 F/g with excellent stability up to 5000 cycles with almost 100\% retention of the initial capacitance in the potential window of -0.7 to 0.5 V. Compared to P-2, P-1 exhibits a specific capacitance of 84 F/g, while the corresponding value for the reference polymer P(NDI2OD-T2) is 61 F/g under identical conditions.

}, issn = {0024-9297}, doi = {10.1021/acs.macromol.7b02425}, author = {Sharma, Sandeep and Soni, Roby and Kurungot, Sreekumar and Asha, S. K.} } @article {44363, title = {Nucleic aptamer modified porous reduced graphene oxide/MoS2 based electrodes for viral detection: application to human papillomavirus (HPV)}, journal = {Sensors and Actuators B-Chemical}, volume = {262}, year = {2018}, month = {JUN}, pages = {991-1000}, type = {Article}, abstract = {Next to graphene nanomaterials, molybdenum disulfide (MoS2) offers large surface area that can enhance its biosensing performance. In this work, we investigate the performance of glassy carbon (GC) electrodes modified successively with porous reduced graphene oxide (prGO) and molybdenum sulfide (MoS2) for the sensitive and selective detection of the L1-major capsid protein of human papilloma virus (HPV). Owing to the difficulties to perform serological assays and HPV culture efficiently, tools based on molecular recognition are becoming of great importance. We developed here an electrochemical sensor for HPV upon covalent functionalization of the electrode with an aptamer Sc5-c3, a RNA aptamer targeted against the HPV-16 L1 protein. Using differential pulse voltammetry (DPV) and an optimized sensor interface, a linear relationship between the peak current density of a redox couple such as [Fe(CN)6]4- and the concentration of HPV-16 L1 proteins in the range of 0.2-2 ng mL(-1) (3.5 pM-35.3 pM) could be reached with a detection limit of 0.1 ng mL(-1) (1.75 pM). Cross-reactivity studies demonstrated high selectivity over potential interfering species such as HPV-16 E6, opening new opportunities of the developed concept for the development of point of care devices. (C) 2018 Elsevier B.V. All rights reserved.}, doi = {10.1016/j.snb.2018.02.065}, author = {Chekin, Fereshteh and Bagga, Komal and Subramanian, Palaniappan and Jijie, Roxana and Singh, Santosh K. and Kurungot, Sreekumar and Boukherroub, Rabah and Szunerits, Sabine} } @article {44552, title = {Porous reduced graphene oxide modified electrodes for the analysis of protein aggregation. Part 2: Application to the analysis of calcitonin containing pharmaceutical formulation}, journal = {Electrochimica Acta}, volume = {266}, year = {2018}, month = {MAR }, pages = {364-372}, abstract = {

In part 1 (A. Vasilescu et al., Porous reduced graphene oxide modified electrodes for the analysis of protein aggregation. Part 1: Lysozyme aggregation at pH 2 and 7.4 Electrochem. Acta, 254 (2017) 375 -383) we proposed porous reduced graphene oxide coated glassy carbon electrode (GC/prGO) in combination with differential pulse voltammetry as a new analytical tool for aggregation studies of proteins. Lysozyme was used as a model to follow its aggregation by electrochemical means at pH 2 and pH 7.4, leading to the formation of amyloid and amorphous aggregates, respectively. Part 2 of this work widens the scope of this approach by investigating a biopharmaceutical product, as the aggregation of peptide based drugs affects their therapeutic activity and can induce allergic reactions in patients. The salmon polypeptide calcitonin (sCT) was chosen as an example of a bioactive peptide with limited pharmaceutical potential due to a tendency to form cytotoxic aggregates and amyloid fibrils. For practical applications, screen printed electrodes (SPE) and flexible electrodes (FE) modified with polydiallyldimethylammonium (PDDA) and prGO by using the layer-by-layer deposition technique have been developed for the detection of sCT. The results indicate that these electrodes can differentiate between formation of amyloid aggregates of calcitonin (2 mg mL(-1)) in citrate buffer to no aggregation in acetate buffer. It was further demonstrated that these electrodes are able to analyze a pharmaceutical drug product of low potency, Miacalcic (8.3 mu g mL(-1)), where no aggregation was observed. (C) 2018 Elsevier Ltd. All rights reserved.

}, keywords = {Calcitonin, Disposable electrodes, Electrochemistry, Porous reduced graphene oxide, Protein aggregation}, issn = {0013-4686}, doi = {10.1016/j.electacta.2018.02.038}, author = {Vasilescu, Alina and Ye, Ran and Boulahneche, Samia and Lamraoui, Sabrina and Jijie, Roxana and Medjram, Mohamed Salah and Gaspar, Szilveszter and Singh, Santosh K. and Kurungot, Sreekumar and Melinte, Sorin and Boukherroub, Rabah and Szunerits, Sabine} } @article {45417, title = {Preparation and investigations of ABPBI membrane for HT-PEMFC by immersion precipitation method}, journal = {Journal of Membrane Science}, volume = {564}, year = {2018}, month = {OCT}, pages = {211-217}, type = {Article}, abstract = {Poly(2,5-benzimidazole) (ABPBI) membranes were prepared by an easy and benign {\textquoteright}immersion precipitation{\textquoteright} method; alleviating drawbacks of conventional solution casting method involving evaporation of the corrosive solvent. The importance of varying inherent viscosity on the properties of resulting membranes was investigated. The porous membranes formed by immersion precipitation method were analyzed for basic properties (water flux, porosity and dimensional analysis). Since the dense structure is required for their applicability for a fuel cell, through-porosity of the formed membranes was successfully eliminated using a unique shrinkage (similar to 50\%) property of ABPBI, initially, at 60 degrees C followed by at higher temperature. The correlation of membranes annealing temperature with the mechanical properties, phosphoric acid doping and proton conductivity was established. The present membranes exhibited high doping level (5.1 mol/RU), proton conductivity (0.083 S cm(-1)) and fuel cell performance. For comparison, solution casted membranes were prepared and analyzed. The OCP (0.91 V) and max power density (766mWcm(-2)) are quite promising features of this new type of membranes.}, issn = { 0376-7388}, doi = {10.1016/j.memsci.2018.07.026}, author = {Chaudhari, Harshal D. and Illathvalappil, Rajith and Kurungot, Sreekumar and Kharul, Ulhas K.} } @article {44373, title = {Rationally designed self-standing V2O5 electrode for high voltage non-aqueous all-solid-state symmetric (2.0 V) and asymmetric (2.8 V) supercapacitors}, journal = {Nanoscale}, volume = {10}, year = {2018}, month = {MAY}, pages = {8741-8751}, abstract = {The maximum capacitive potential window of certain pseudocapacitive materials cannot be accessed in aqueous electrolytes owing to the low dissociation potential of 1.2 V possessed by water molecules. However, the inferior pseudocapacitance exhibited by the commonly used electrode materials when integrated with non-aqueous electrolytes still remains a challenge in the development of supercapacitors (SC). Proper selection of materials for the electrode and a rational design process are indeed important to overcome these practical intricacies so that such systems can perform well with non-aqueous electrolytes. We address this challenge by fabricating a prototype all-solid-state device designed with high-capacitive V2O5 as the electrode material along with a Li-ion conducting organic electrolyte. V2O5 is synthesized on a pre-treated carbon-fibre paper by adopting an electrochemical deposition technique that effects an improved contact resistance. A judicious electrode preparation strategy makes it possible to overcome the constraints of the low ionic and electrical conductivities imposed by the electrolyte and electrode material, respectively. The device, assembled in a symmetrical fashion, achieves a high specific capacitance of 406 F g(-1) (at 1 A g(-1)). The profitable aspect of using an organic electrolyte is also demonstrated with an asymmetric configuration by using activated carbon as the positive and V2O5 as the negative electrode materials, respectively. The asymmetric device displays a wide working-voltage window of 2.8 V and delivers a high energy density of 102.68 W h kg(-1) at a power density of 1.49 kW kg(-1). Moreover, the low equivalent series resistance of 9.9 Omega and negligible charge transfer resistance are observed in the impedance spectra, which is a key factor that accounts for such an exemplary performance.}, doi = {10.1039/c8nr00805a}, author = {Ghosh, Meena and Vijayakumar, Vidyanand and Soni, Roby and Kurungot, Sreekumar} } @article {44218, title = {Realizing high capacitance and rate capability in polyaniline by enhancing the electrochemical surface area through induction of superhydrophilicity}, journal = {ACS Applied Materials \& Interfaces}, volume = {10}, year = {2018}, month = {JAN}, pages = {676-686}, type = {Article}, abstract = {

Polyaniline (PANI) as a pseudocapacitive material has very high theoretical capacitance of 2000 F g(-1). However, its practical capacitance has been limited by low electrochemical surface area (ESA) and unfavorable wettability toward aqueous electrolytes. This work deals with a strategy wherein the high ESA of PANI has been achieved by the induction of superhydrophilicity together with the alignment of PANI exclusively on the surface of carbon fibers as a thin layer to form a hybrid assembly. Superhydrophilicity is induced by electrochemical functionalization of the Toray carbon paper, which further induces superhydrophilicity to the electrodeposited PANI layer on the paper, thereby ensuring a high electrode-electrolyte interface. The Toray paper is electrochemically functionalized by the anodization method, which generates a highly active electrochemical surface as well as greater wettability (superhydrophilic) of the carbon fibers. Because of the strong interaction of anilinium chloride with the hydrophilic carbon surface, PANI is polymerized exclusively over the surface of the fibers without any appreciable aggregation or agglomeration of the polymer. The PANI-Toray paper assembly in the solid-state prototype supercapacitor can provide a high gravimetric capacitance of 1335 F g(-1) as well as a high areal capacitance of 1.3 F cm(-2) at a current density of 10 A g(-1). The device also exhibits high rate capability, delivering 1217 F g(-1) at a current density of 50 A g(-1) and a high energy density of 30 W h kg(-1) at a power density of 2 kW kg(-1).

}, keywords = {electrochemical active sulfate area, electrochemical functionalization, electropolymerization, polyaniline, supercapacitor, superhydrophilic}, issn = {1944-8244}, doi = {10.1021/acsami.7b15534}, author = {Soni, Roby and Kashyap, Varchaswal and Nagaraju, Divya and Kurungot, Sreekumar} } @article {44643, title = {Repeated photoporation with graphene quantum dots enables homogeneous labeling of live cells with extrinsic markers for fluorescence microscopy}, journal = {Light-Science \& Applications}, volume = {7}, year = {2018}, month = {AUG}, pages = {47}, abstract = {

In the replacement of genetic probes, there is increasing interest in labeling living cells with high-quality extrinsic labels, which avoid over-expression artifacts and are available in a wide spectral range. This calls for a broadly applicable technology that can deliver such labels unambiguously to the cytosol of living cells. Here, we demonstrate that nanoparticle-sensitized photoporation can be used to this end as an emerging intracellular delivery technique. We replace the traditionally used gold nanoparticles with graphene nanoparticles as photothermal sensitizers to permeabilize the cell membrane upon laser irradiation. We demonstrate that the enhanced thermal stability of graphene quantum dots allows the formation of multiple vapor nanobubbles upon irradiation with short laser pulses, allowing the delivery of a variety of extrinsic cell labels efficiently and homogeneously into live cells. We demonstrate high-quality time-lapse imaging with confocal, total internal reflection fluorescence (TIRF), and Airyscan super-resolution microscopy. As the entire procedure is readily compatible with fluorescence (super resolution) microscopy, photoporation with graphene quantum dots has the potential to become the long-awaited generic platform for controlled intracellular delivery of fluorescent labels for live-cell imaging.

}, issn = {2047-7538}, doi = {10.1038/s41377-018-0048-3}, author = {Liu, Jing and Xiong, Ranhua and Brans, Toon and Lippens, Saskia and Parthoens, Eef and Zanacchi, Francesca Cella and Magrassi, Raffaella and Singh, Santosh K. and Kurungot, Sreekumar and Szunerits, Sabine and Bove, Hannelore and Ameloot, Marcel and Fraire, Juan C. and Teirlinck, Eline and Samal, Sangram Keshari and De Rycke, Riet and Houthaeve, Gaelle and De Smedt, Stefaan C. and Boukherroub, Rabah and Braeckmans, Kevin} } @article {44362, title = {Sensitive electrochemical detection of cardiac troponin I in serum and saliva by nitrogen-doped porous reduced graphene oxide electrode}, journal = {Sensors and Actuators B-Chemical}, volume = {262}, year = {2018}, month = {JUN}, pages = {180-187}, type = {Article}, abstract = {Cardiovascular diseases pose one of the highest mortality risks among all diseases in developed countries, steadily increasing the burden on the health systems. Early diagnosis of cardiovascular diseases has consequently become highly important to decrease mortality and to use more adapted therapeutic decisions. We demonstrate here the utility of nitrogen-doped reduced graphene oxide (N-prGO) for detecting and quantifying of cardiac troponin I (cTnI), a key human cardiac protein biomarker, under physiologically relevant conditions. Non-covalent modification of N-prGO by 1-pyrenecarboxylic acid (py-COOH) and poly(ethylene glycol) modified pyrene (py-PEG) ligands allowed the covalent integration of Tro4 aptamer, known for its high selectivity towards cTnI. Using differential pulse voltammetry (DPV), a label-free electrochemical sensor for cTnI for concentrations down to 1 pgmL(-1) in human serum could be obtained. This sensitive detection arises from the integration of a porous nanomaterial with excellent electrochemical properties being easily amendable to site-specific surface modification. (C) 2018 Elsevier B.V. All rights reserved.}, doi = {10.1016/j.snb.2018.01.215}, author = {Chekin, Fereshteh and Vasilescu, Alina and Jijie, Roxana and Singh, Santosh K. and Kurungot, Sreekumar and Iancu, Madalina and Badea, Gabriela and Boukherroub, Rabah and Szunerits, Sabine} } @article {44609, title = {Superprotonic conductivity in flexible porous covalent organic framework membranes}, journal = {Angewandte Chemie}, volume = {57}, year = {2018}, month = {AUG}, pages = {10894-10898}, type = {Article}, abstract = {

Poor mechanical stability of the polymer electrolyte membranes (PEMs) remains one of the bottlenecks towards improving the performance of the proton exchange membrane (PEM) fuel cells. The present work proposes a unique way to utilize crystalline covalent organic frameworks (COFs) as a self-standing, highly flexible membrane to further boost the mechanical stability of the material without compromising its innate structural characteristics. The as-synthesized p-toluene sulfonic acid loaded covalent organic framework membranes (COFMs) showing the highest proton conductivity amongst all crystalline porous organic polymeric materials reported till date, as high as 7.8 x 10-2 S cm-1, have been further tested under real PEM operating conditions to ascertain their practical utilization as proton exchange membranes. Attainment of 24 mW cm-2 power density, which is the highest among COFs and MOFs, highlights the possibilityof using a COF membrane over the other state-of-the-art crystalline porous polymeric materials reported to date.

}, doi = {10.1002/ange.201804753}, author = {Banerjee, Rahul and Sasmal, Himadri Sekhar and Harshitha, B. A. and Bhange, Siddheshwar and Karak, Suvendu and Halder, Arjun and Kurungot, Sreekumar} } @article {44425, title = {Water mediated proton conductance in a hydrogen-bonded Ni(II)-bipyridine-glycoluril chloride self-assembled framework}, journal = {CrystEngComm}, volume = {20}, year = {2018}, month = {JAN}, pages = {1094-1100}, type = {Journal Article}, abstract = {

Proton conducting properties have been investigated in a new Ni(II)-based hydrogen-bonded porous framework synthesized using a urea-fused bipyridine-glycoluril (BPG) tecton. This hydrogen-bonded self-assembled structure encapsulates water molecules in the channels with hydrogen-bonding networks which exhibits a significant temperature dependent proton conductance of 1.5 \× 10\−4\ S cm\−1\ at 95 \°C and 95\% RH with a low activation energy (Ea) of 0.54 eV, implying a Grotthuss proton hopping mechanism mediated by hydrogen-bonded water molecules in the channels. In addition, this framework exhibited a very high water uptake under humid conditions. A continuous array of water molecules and chloride ions embedded in the highly hydrophilic porous channels of the hydrogen-bonded framework acts as the proton conducting medium.

}, issn = {14668033}, doi = {10.1039/c7ce01814b}, author = {Tayade, Sakharam B. and Bhat, Satish S. and Illathvalappil, Rajith and Dhavale, Vishal M. and Kawade,Vitthal A. and Kumbhar, Avinash S. and Kurungot, Sreekumar and N{\"a}ther, Christian} } @article {45449, title = {Water-in-acid gel polymer electrolyte realized through a phosphoric acid-enriched polyelectrolyte matrix toward solid-state supercapacitors}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {6}, year = {2018}, month = {OCT}, pages = {12630-12640}, type = {Article}, abstract = {A new concept of water-in-acid gel polymer electrolytes (GPEs) is introduced. The simple and scalable UV-light-assisted synthesis of a copolymer matrix possessing polyelectrolyte behavior, followed by swelling in minimally diluted H3PO4 (15.1 M/88 wt \% aqueous solution), effects formation of a high proton-conducting, self-standing, and mechanically stable polyelectrolyte GPE (PGPE). Retention of high mechanical stability despite the presence of a large amount of liquid species makes it a promising candidate for replacing conventional GPEs. The high proton conductivity (9.8 X 10(-2) S cm(-1)) of the PGPE at an ambient temperature of 303 K is attributed to the high concentration of the conducting species present in the polymer matrix. The PGPE-based polyaniline (PANI) supercapacitor device (PANI-1) with a mass loading of 1 mg cm(-2) exhibits a high specific gravimetric capacitance of 385 F g(-1) at a current density of 0.25 mA cm(-2). At the same current density, the PANI-5 device retains high gravimetric and areal capacitance values of 258 F g(-1) and 1288 mF cm(-2), respectively. The low equivalent series resistance value of 0.78 Omega (for the PANI-5 device) further proves the excellent electrode-electrolyte interface formed by the water-in-acid GPE. A 100\% capacitance retention even after 9000 continuous charge-discharge cycles strongly indicates the feasibility of adopting water-in-acid GPEs in future supercapacitors.}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.8b01175}, author = {Vijayakumar, Vidyanand and Ghosh, Meena and Torris, Arun A. T. and Chandran, Nikhil M. K. and Nair, Sanoop B. and Badiger, Manohar V. and Kurungot, Sreekumar} } @article {46127, title = {3-D nanoribbon-like Pt-free oxygen reduction reaction electrocatalyst derived from waste leather for anion exchange membrane fuel cells and zinc-air batteries}, journal = {Nanoscale}, volume = {11}, year = {2019}, month = {APR }, pages = {7893-7902}, type = {Article}, abstract = {

Fe-N-x and Fe-S-based ORR electrocatalysts have emerged as rightful candidates to replace Pt in fuel cells to make the technology cheap and sustainable. Fe-N-C catalysts are generally prepared by the pyrolysis of conducting polymers, metal-organic frameworks, aerogels, etc., and the combination of multiple heteroatoms and metal precursors. These precursors are mostly expensive and their synthesis involves multiple steps. In this report, we have demonstrated the synthesis of a Fe-N-C catalyst from the waste leather obtained from the footwear and other leather-consuming industries. The pyrolysis of leather with FeCl3 (metal source) results in the formation of a highly thin and porous nano-ribbon like morphology. Waste leather acts as a cost-free single source of heteroatoms like N, S and carbon. The catalyst synthesized at a temperature of 900 degrees C shows an overpotential of 40 mV and better durability compared to the commercial Pt/C catalyst. The catalyst is demonstrated as the cathode for alkaline exchange membrane fuel cell (AEMFC) and zinc-air battery (ZAB) applications. In the AEMFC, a power density of 50 mW cm(-2) and an OCV of 0.92 V are obtained whereas, in the ZAB, it exhibited a power density of 174 mW cm(-2) compared to 160 mW cm(-2) of the system based on the Pt/C catalyst.

}, issn = {2040-3364}, doi = {10.1039/c9nr00977a}, author = {Soni, Roby and Bhange, Siddheshwar N. and Kurungot, Sreekumar} } @article {46294, title = {Carbon derived from soft pyrolysis of a covalent organic framework as a support for small-sized RuO2 showing exceptionally low overpotential for oxygen evolution reaction}, journal = {ACS Omega}, volume = {4}, year = {2019}, month = {AUG}, pages = {13465-13473}, type = {Article}, abstract = {

Electrochemical water splitting is the most energy-efficient technique for producing hydrogen and oxygen, the two valuable gases. However, it is limited by the slow kinetics of the anodic oxygen evolution reaction (OER), which can be improved using catalysts. Covalent organic framework (COF)-derived porous carbon can serve as an excellent catalyst support. Here, we report high electrocatalytic activity of two composites, formed by supporting RuO2 on carbon derived from two COFs with closely related structures. These composites catalyze oxygen evolution from alkaline media with overpotentials as low as 210 and 217 mV at 10 mA/cm(2), respectively. The Tafel slopes of these catalysts (65 and 67 mV/dec) indicate fast kinetics compared to commercial RuO2. The observed activity is the highest among all RuO2-based heterogeneous OER catalysts-a touted benchmark OER catalyst. The high catalytic activity arises from the extremely small-sized (similar to 3-4 nm) RuO2 nanoparticles homogeneously dispersed in a micro-mesoporous (BET = 517 m(2)/g) COF-derived carbon. The porous graphenic carbon favors mass transfer, while its N-rich framework anchors the catalytic nanoparticles, making it highly stable and recyclable. Crucially, the soft pyrolysis of the COF enables the formation of porous carbon and simultaneous growth of small RuO2 particles without aggregation.

}, issn = {2470-1343}, doi = {10.1021/acsomega.9b01777}, author = {Chakraborty, Debanjan and Nandi, Shyamapada and Illathvalappil, Rajith and Mullangi, Dinesh and Maity, Rahul and Singh, Santosh K. and Haldar, Sattwick and Vinod, Chathakudath P. and Kurungot, Sreekumar and Vaidhyanathan, Ramanathan} } @article {46208, title = {A copper(ii)-coordination polymer based on a sulfonic-carboxylic ligand exhibits high water-facilitated proton conductivity}, journal = {Dalton Transactions}, volume = {48}, year = {2019}, month = {AUG}, pages = {11034-11044}, type = {Article}, abstract = {

Proton conduction ability has been investigated in a new Cu(ii) based coordination polymer (CP), {[Cu-2(sba)(2)(bpg)(2)(H2O)(3)]center dot 5H(2)O}(n) (1), synthesized using the combination of 4-sulfobenzoic acid (4-Hsba) and bipyridine-glycoluril (BPG) ligands. Single crystal X-ray structure determination revealed that 1 features 1D porous channels encapsulating a continuous array of water molecules. Proton conductivity measurements reveal a high conductivity value of 0.94 x 10(-2) S cm(-1) at 80 degrees C and 95\% RH. The activation energy (E-a) of 0.64 eV demonstrates that the solvate water, coordinated water and hydrophilic groups in the channels promote the mobility of protons in the framework. Water sorption measurements exhibited hysterical behaviour with a high uptake value of 379.07 cm(3) g(-1). Time-dependent measurements revealed that the proton conductivity is retained even after 12 h of measurements. The proton conduction mechanism was validated by ab initio electronic structure calculations using the Nudged Elastic Band (NEB) method with molecular dynamics (MD) simulation studies. The theoretical activation energy is calculated to be 0.54 eV which is in accordance with the experimental value.

}, doi = {10.1039/c9dt01983a}, author = {Tayade, Sakharam B. and Illathvalappil, Rajith and Lapalikar, Vaidehi and Markad, Datta and Kurungot, Sreekumar and Pujari, Bhatchandra and Kumbhar, Avinash S.} } @article {46351, title = {Cubic palladium nanorattles with solid octahedron gold core for catalysis and alkaline membrane fuel cell applications}, journal = {ChemCatChem}, volume = {11}, year = {2019}, month = {SEP }, pages = {4383-4392}, type = {Article}, abstract = {

Herein, we report the synthesis of palladium nanorattles (Au-Pd NRTs) comprising of a gold octahedral core caged within a thin porous cubic palladium shell. The introduction of core-shell and porous architecture was realized by combining seed mediated and galvanic replacement reaction techniques. Next, we examined the catalytic efficiency of the nanocatalyst in comparison with solid palladium nanocube (Pd-NC) of similar size for the degradation of p-nitrophenol and organic dyes. The rate constant of Au-Pd NRTs was found nearly 12 times higher than the Pd-NCs. Further, we exploited our catalyst for electrochemical oxygen reduction reaction (ORR) and observed its high intrinsic ORR activity. Compared with commercialized Pt/C, the Au-Pd NRT displayed nearly comparable onset and half-wave potential values and excellent durability upon potential cycling. The system level validation in a single-cell mode of alkaline exchange membrane fuel cell also confirms the efficiency of the present catalyst to serve as a potential cathode catalyst for realistic device applications.

}, keywords = {alkaline exchange membrane fuel cell, electrocatalysis, nanorattles, ORR, Pd nanoparticle}, issn = {1867-3880}, doi = {10.1002/cctc.201900741}, author = {Singh, Prem and Sonika and Gangadharan, Pranav K. and Khan, Ziyauddin and Kurungot, Sreekumar and Jaiswal, Amit} } @article {46255, title = {Dendrite growth suppression by Zn2+-integrated nafion ionomer membranes: beyond porous separators toward aqueous Zn/V2O5 batteries with extended cycle life }, journal = {Energy Technology}, volume = {7}, year = {2019}, month = {SEP}, type = {Article}, abstract = {

The dendritic/irregular growth of zinc deposits in the anode surface is often considered as a major intricacy limiting the lifespan of aqueous zinc-ion batteries. The effect of separators on the evolution of the surface morphology of the anode/cathode is never thoroughly studied. Herein, for the first time, the efficacy of the Zn2+-integrated Nafion ionomer membrane is demonstrated as a separator to effectively suppress the growth of irregular zinc deposits in the metallic anode of an aqueous Zn/V2O5 battery. The Zn2+-ions coordinated with the SO3- moieties in Nafion result in a high transference number of the Zn2+ cation, all the while facilitating a high ionic conductivity. The Zn2+-integrated Nafion membrane enables the Zn/V2O5 cell to deliver a high specific capacity of 510 mAh g(-1) at a current of 0.25 A g(-1), which is close to the theoretical capacity of anhydrous V2O5 (589 mAh g(-1)). Moreover, the same cell exhibits an excellent cycling stability of 88\% retention of the initial capacity even after 1800 charge-discharge cycles, superior to that of the Zn/V2O5 cells comprising conventional porous separators.

}, doi = {10.1002/ente.201900442}, author = {Ghosh, Meena and Vijayakumar, Vidyanand and Kurungot, Sreekumar} } @article {45516, title = {Fe2P4O12-carbon composite as a highly stable electrode material for electrochemical capacitors}, journal = {New Journal of Chemistry}, volume = {43}, year = {2019}, month = {JAN}, pages = {399-406}, type = {Article}, abstract = {

Supercapacitors are important energy storage devices for high power applications. Carbon materials, metal oxides and conducting polymers have been known to show capacitive charge storage but transition metal phosphates are not as well-known as electrode materials in supercapacitors. In this study, an iron cyclotetraphosphate (Fe2P4O12)-carbon composite has been synthesized and demonstrated as an electrode material for supercapacitors. The Fe2P4O12-carbon composite has been thoroughly characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, electron microscopy, etc. The composite shows predominant capacitive behaviour only in acidic medium; its charge storage properties are relatively poor in alkaline medium, indicating the important role of H+ in the charge storage mechanism. The composite shows a capacitance of 251 F g(-1) at a current density of 1 A g(-1). The composite is highly stable in 0.5 M H2SO4 and does not show any apparent capacitance loss after 9000 charge-discharge cycles recorded at a current density of 5 A g(-1).

}, issn = {1144-0546}, doi = {10.1039/c8nj04671a}, author = {Soni, Roby and Kurungot, Sreekumar} } @article {46430, title = {Glycine-induced electrodeposition of nanostructured cobalt hydroxide: a bifunctional catalyst for overall water splitting}, journal = {ChemSusChem}, year = {2019}, month = {NOV}, type = {Article; Early Access}, abstract = {

Herein, an interconnected alpha-Co(OH)(2) structure with a network-like architecture was used as a bifunctional electrocatalyst for the overall water splitting reaction in alkaline medium. The complexing ability of glycine with a transition metal was exploited to form [Co(gly)(3)](-) dispersion at pH 10, which was used for the electrodeposition. High-resolution TEM, UV/Vis-diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy were used to confirm that the as-synthesized materials had an alpha-Co(OH)(2) phase. The electrocatalytic oxygen and hydrogen evolution activity of the glycine-coordinated alpha-Co(OH)(2) was found to be approximately 320 and 145 mV, respectively, at 10 mA cm(-2). The material required approximately 1.60 V (vs. reversible hydrogen electrode; RHE) to achieve the benchmark of 10 mA cm(-2) for overall water splitting with a mass activity of approximately 63.7 A g(-1) at 1.60 V (vs. RHE). The chronoamperometric response was measured to evidence the stability of the material for overall water splitting for up to 24 h. Characterization of the catalyst after the oxygen and hydrogen evolution reactions was performed by XPS and showed the presence of a Co-II/Co-III oxidation state.

}, keywords = {cobalt, Electrochemistry, heterogeneous catalysis, Hydrogen, water splitting}, issn = {1864-5631}, doi = {10.1002/cssc.201902323}, author = {Shilpa, Nagaraju and Nadeema, Ayasha and Kurungot, Sreekumar} } @article {46179, title = {Graphene-modified electrodes for sensing doxorubicin hydrochloride in human plasma}, journal = {Analytical and Bioanalytical Chemistry}, volume = {411}, year = {2019}, month = {MAR}, pages = {1509-1516}, type = {Article}, abstract = {

Doxorubicin (DOX), an anthracycline molecule, is currently one of the most widely used anticancer drugs in clinics. Systematic treatment of patients with DOX is known to be accompanied by several unpleasant side effects due to the toxicity of the drug. Thus, monitoring of DOX concentration in serum samples has become increasingly important to avoid side effects and ensure therapeutic efficiency. In this study, we discuss the construction of a disposable electrochemical sensor for the direct monitoring of DOX in clinical blood samples. The sensor is based on coating a gold electrode in a flexible integrated electrode construct formed on polyimide sheets using photolithography, with nitrogen-doped reduced graphene oxide (N-rGO) suspended in chitosan. Under optimized conditions, a linear relationship between the oxidative peak current and the concentration of DOX in the range of 0.010-15M with a detection limit of 10nM could be achieved. The sensor was adapted to monitor DOX in serum samples of patients under anticancer treatment.

}, keywords = {Disposable electrodes, doxorubicin, Nitrogen-doped reduced graphene oxide, Serum}, issn = {1618-2642}, doi = {10.1007/s00216-019-01611-w}, author = {Chekin, Fereshteh and Myshin, Vladyslav and Ye, Ran and Melinte, Sorin and Singh, Santosh K. and Kurungot, Sreekumar and Boukherroub, Rabah and Szunerits, Sabine} } @article {46177, title = {High-performing PGM-free AEMFC cathodes from carbon-supported cobalt ferrite nanoparticles}, journal = {Catalysts}, volume = {9}, year = {2019}, month = {MAR}, pages = {264}, type = {Article}, abstract = {

Efficient and durable non-precious metal electrocatalysts for the oxygen reduction reaction (ORR) are highly desirable for several electrochemical devices, including anion exchange membrane fuel cells (AEMFCs). Here, cobalt ferrite (CF) nanoparticles supported on Vulcan XC-72 carbon (CF-VC) were created through a facile, scalable solvothermal method. The nano-sized CF particles were spherical with a narrow particle size distribution. The CF-VC catalyst showed good ORR activity, possessing a half-wave potential of 0.71 V. Although the intrinsic activity of the CF-VC catalyst was not as high as some other platinum group metal (PGM)-free catalysts in the literature, where this catalyst really shined was in operating AEMFCs. When used as the cathode in a single cell 5 cm(-2) AEMFC, the CF-VC containing electrode was able to achieve a peak power density of 1350 mW cm(-2) (iR-corrected: 1660 mW cm(-2)) and a mass transport limited current density of more than 4 A cm(-2) operating on H-2/O-2. Operating on H-2/Air (CO2-free), the same cathode was able to achieve a peak power density of 670 mW cm(-2) (iR-corrected: 730 mW cm(-2)) and a mass transport limited current density of more than 2 A cm(-2). These peak power and achievable current densities are among the highest reported values in the literature to date.

}, keywords = {AEMFC, cobalt, Ferrite, high-performing, non-PGM, vulcan}, issn = {2073-4344}, doi = {10.3390/catal9030264}, author = {Peng, Xiong and Kashyap, Varchaswal and Ng, Benjamin and Kurungot, Sreekumar and Wang, Lianqin and Varcoe, John R. and Mustain, William E.} } @article {46348, title = {Imidazole-linked crystalline two-dimensional polymer with ultrahigh proton-conductivity}, journal = {Journal of the American Chemical Society}, volume = {141}, year = {2019}, month = {SEP}, pages = {14950-14954}, type = {Article}, abstract = {

Proton-exchange membrane fuel cells are promising energy devices for a sustainable future due to green features, high power density, and mild operating conditions. A facile proton-conducting membrane plays a pivotal role to boost the efficiency of fuel cells, and hence focused research in this area is highly desirable. Major issues associated with the successful example of Nafion resulted in the search for alternate proton conducting materials. Even though proton carrier loaded crystalline porous organic frameworks have been used for protonconduction, the weak host-guest interactions limited their practical use. Herein, we developed a crystalline 2D-polymer composed of benzimidazole units as the integral part, prepared by the condensation of aryl acid and diamine in polyphosphoric acid medium. The imidazole linked-2D-polymer exhibits ultrahigh proton conductivity (3.2 X 10(-2) S cm(-1)) (at 95\% relative humidity and 95 degrees C) in the pristine state, which is highest among the undoped porous organic frameworks so far reported. The present strategy of a crystalline proton-conducting 2D-polymer will lead to the development of new high performing crystalline solid proton conductor.

}, issn = {0002-7863}, doi = {10.1021/jacs.9b06080}, author = {Ranjeesh, Kayaramkodath Chandran and Ilathvalappil, Rajith and Veer, Sairam Dnyaneshwar and Peter, Joseph and Wakchaure, Vivek Chandrakant and Goudappagouda and Raj, K. Vipin and Kurungot, Sreekumar and Babu, Sukumaran Santhosh} } @article {46305, title = {In-situ generated Mn3O4-reduced graphene oxide nanocomposite for oxygen reduction reaction and isolated reduced graphene oxide for supercapacitor applications}, journal = {Carbon}, volume = {154}, year = {2019}, month = {DEC}, pages = {285-291}, type = {Article}, abstract = {

We have generated in situ nanocomposite of Mn3O4 and reduced graphene oxide (rGO) upon employing wet-chemical reduction of graphene oxide (GO) by Mn(II) salt as mild-reducing agent for the first time and examined the oxygen reduction reaction (ORR) activity in 0.1 M KOH electrolyte. The half-wave potential (E-1/2) of the nanocomposite catalyst (20\% Mn3O4-rGO/C) was found to be around -0.153 V which is only similar to 87 mV negative from the commercially available catalyst (20\% Pt/C). Remarkably, after 5000 linear sweep voltammetry cycles the E-1/2 shifted marginally by 20 mV; and the number of electrons transferred during ORR was estimated to be close to 4. Such an efficient electrocatalytic performance of the nanocomposite was primarily attributed to the synergistic interaction between Mn3O4 and rGO. The fabricated all-solid-state supercapacitor of rGO (extracted from the nanocomposite) in aqueous polyvinyl alcohol-sulfuric acid (PVA-H2SO4) gel polymer electrolyte (GPE) showed C-s value of similar to 310 F/g at a current density of 1 A/g along with long durability (10,000 charge-discharge cycles). All-solid-state flexible rGO supercapacitor exhibited high-flexibility and excellent durability (30,000 cycles with 100\% retention of C-s). Our results provide an enormous opportunity in designing transition metal oxides decorated semiconducting reduced graphene oxide nanocomposite platforms for various electrochemical applications. (C) 2019 Elsevier Ltd. All rights reserved.

}, issn = {0008-6223}, doi = {10.1016/j.carbon.2019.08.012}, author = {Jha, Plawan Kumar and Kashyap, Varchaswal and Gupta, Kriti and Kumar, Vikash and Debnath, Anil Krishna and Roy, Debashree and Rana, Shammi and Kurungot, Sreekumar and Ballav, Nirmalya} } @article {46052, title = {[MoS4](2-)-Intercalated NiCo-layered double hydroxide nanospikes: an efficiently synergized material for urine to direct H-2 generation}, journal = {ACS Applied Materials \& Interfaces}, volume = {11}, year = {2019}, month = {JUL }, pages = {25917-25927}, type = {Article}, abstract = {

Substituting the energy-uphill water oxidation half-cell with readily oxidizable urea-rich urine, a ground-breaking bridge is constructed, combining the energy-efficient hydrogen generation and environmental 6 protection. Hence, designing a robust multifunctional electrocatalyst is desirable for widespread implementation of this waste to fuel technology. In this context, here, we report a simple tuning of the electrocatalytically favorable characteristics of NiCo-layered double hydroxide by introducing [MoS4]2- in its interlayer space. The [MoS4]{\textquoteright} insertion as well as its effect on the electronic structure tuning is thoroughly studied via X-ray photoelectron spectroscopy in combination with electrochemical analysis. This insertion induces overall electronic structure tuning of the hydroxide layer in such a way that the designed catalyst exhibited favorable kinetics toward all the required reactions of hydrogen generation. This is why our homemade catalyst, when utilized both as a cathode and anode to fabricate a urea electrolyzer, required a mere X1.37 V cell potential to generate sufficient H2 by reaching the benchmark 10 mA cm-2 in 1 M KOH/0.33 M urea along with long-lasting catalytic efficiency. Other indispensable reason of selecting [MoS4]2- is its high-valent nature making the catalyst highly selective and insensitive to common catalyst-poisoning toxins of urine. This is experimentally supported by performing the real urine electrolysis, where the nanospike-covered Ni foam-based catalyst showed a performance similar to that of synthetic urea, offering its industrial value. Other intuition of selecting [MoS4]2- was to provide a ligand-based mechanism for hydrogen evolution half-cell [hydrogen evolution reaction (HER)] to preclude the HER-competing oxygen reduction. Another crucial point of our work is its potential to avoid the mixing of two explosive product gases, that is, H2 and O-2.

}, keywords = {hydrogen evolution reaction, Layered double hydroxide, nickel oxyhydroxide, sewage denitrification, urea oxidation reaction, urine/urea electrolysis}, issn = {1944-8244}, doi = {10.1021/acsami.9b06545}, author = {Nadeema, Ayasha and Kashyap, Varchaswal and Gururaj, Rakshitha and Kurungot, Sreekumar} } @article {45512, title = {Studies on nano composites of SPEEK/ethylene glycol/cellulose nanocrystals as promising proton exchange membranes}, journal = {Electrochimica Acta}, volume = {293}, year = {2019}, month = {JAN }, pages = {260-272}, type = {Article}, abstract = {

The present work deals with fabrication and characterisations of nano-composite membranes composed of sulfonated poly (ether ether ketone) (SPEEK) cross-linked and reinforced with ethylene glycol (EG) and cellulose nanocrystals (CNCs) respectively. The thin films of cross-linked composite membranes were prepared by solvent casting method and further analysed for physicochemical and electrochemical properties to execute their applicability as promising proton exchange membrane (PEM) in fuel cells. The process of cross-linking helps to improve the strength and dimensional stability of bare SPEEK membranes without compromising with conductivity. However, presence of CNCs further improves the strength and provides an effective pathway for the conduction of protons in membranes by interacting through their surface hydroxyl and sulfonic acid groups with ionic moieties of polymer matrix. All prepared composite membranes showed good oxidative and thermal stability along with good proton conductivity. The cross-linked SPEEK membranes with 4 wt\% loading of CNCs possess an appreciable proton conductivity of 0.186 S/cm at 95 degrees C and 95\% RH which is comparable to Nafion 117. From the view point of above studies, the prepared nano-composite can be described as promising proton exchange membrane for fuel cells. (c) 2018 Elsevier Ltd. All rights reserved.

}, keywords = {Cellulose nanocrystals, Cross-linked SPEEK, fuel cell, oxidative stability, proton conductivity}, issn = {0013-4686}, doi = {10.1016/j.electacta.2018.10.029}, author = {Bano, Saleheen and Negi, Yuvraj S. and Illathvalappil, Rajith and Kurungot, Sreekumar and Ramya, K.} } @article {46164, title = {Synthesis of ultrathin PEDOT on carbon nanotubes and shear thinning xanthan Gum-H2SO4 gel electrolyte for supercapacitors}, journal = {ChemElectroChem}, volume = {6}, year = {2019}, month = {MAR }, pages = {1861-1869}, type = {Article}, abstract = {

Resistance of the electrode material play a vital role for applications in supercapacitors, where lowering the resistance leads to improved performance. Poly(3,4-ethylene dioxythiophene) (PEDOT) possesses high theoretical conductivity; however, the high density of grain boundaries, low accessible surface area, and low rate capability have been pervasive issues affecting the PEDOT-based supercapacitors. To this end, a hydrothermal method is proposed in this work where oxygen functional groups incorporated on the surface of carbon nanotubes (CNTs) are utilized to polymerize 3,4-ethylenedioxythiophene (EDOT). PEDOT forms an ultrathin, well-aligned coating on the surface of CNTs. This arrangement minimizes the number of grain boundaries and increases the electrochemically active surface area. Additionally, a shear-thinning Xanthan gum-H2SO4 gel electrolyte is introduced to overcome the low impregnation of the conventional polyvinyl-based electrolyte due to the hydrophobicity of the CNT-PEDOT composite. A supercapacitor based on this material showed a very low Equivalent Series Resistance (ESR) of 0.31 which leads to a high power density of 74 W cm(-3).

}, keywords = {gel electrolyte, PEDOT, shear thinning, supercapacitor, xanthan gum}, issn = {2196-0216}, doi = {10.1002/celc.201801780}, author = {Soni, Roby and Bhange, Siddheshwar N. and Athira, E. and Chetry, Rashmi and Kurungot, Sreekumar} } @article {46231, title = {Weak intermolecular interactions in covalent organic framework-carbon nanofiber based crystalline yet flexible devices}, journal = {ACS Applied Materials \& Interfaces}, volume = {11}, year = {2019}, month = {AUG}, type = {Article}, abstract = {

The redox-active and porous structural backbone of covalent organic frameworks (COFs) can facilitate high-performance electrochemical energy storage devices. However, the utilities of such 2D materials as supercapacitor electrodes in advanced self-charging power-pack systems have been obstructed due to the poor electrical conductivity and subsequent indigent performance. Herein, we report an effective strategy to enhance the electrical conductivity of COF thin sheets through the in situ solid-state inclusion of carbon nanofibers (CNF) into the COF precursor matrix. The obtained COF-CNF hybrids possess a significant intermolecular Ï€{\textperiodcentered}{\textperiodcentered}{\textperiodcentered}Ï€ interaction between COF and the graphene layers of the CNF. As a result, these COF-CNF hybrids (DqTp-CNF and DqDaTp-CNF) exhibit good electrical conductivity (0.25 {\texttimes} 10{\textendash}3\ S cm{\textendash}1), as well as high performance in electrochemical energy storage (DqTp-CNF: 464 mF cm{\textendash}2\ at 0.25 mA cm{\textendash}2). Also, the fabricated, mechanically strong quasi-solid-state supercapacitor (DqDaTp-CNF SC) delivered an ultrahigh device capacitance of 167 mF cm{\textendash}2\ at 0.5 mA cm{\textendash}2. Furthermore, we integrated a monolithic photovoltaic self-charging power pack by assembling DqDaTp-CNF SC with a perovskite solar cell. The fabricated self-charging power pack delivered excellent performance in the areal capacitance (42 mF cm{\textendash}2) at 0.25 mA cm{\textendash}2\ after photocharging for 300 s.

}, doi = {10.1021/acsami.9b08625}, author = {Mohammed, Abdul Khayum and Vijayakumar, Vidyanand and Halder, Arjun and Ghosh, Meena and Addicoat, Matthew and Bansode, Umesh and Kurungot, Sreekumar and Banerjee, Rahul} } @article {46233, title = {Zinc ion interactions in a two-dimensional covalent organic framework based aqueous zinc ion battery}, journal = {Chemical Science}, year = {2019}, month = {AUG}, type = {Article}, abstract = {

The two-dimensional structural features of covalent organic frameworks (COFs) can promote the electrochemical storage of cations like H+, Li+, and Na+\ through both faradaic and non-faradaic processes. However, the electrochemical storage of cations like Zn2+\ ion is still unexplored although it bears a promising divalent charge. Herein, for the first time, we have utilized hydroquinone linked β-ketoenamine COF acting as a Zn2+\ anchor in an aqueous rechargeable zinc ion battery. The charge-storage mechanism comprises of an efficient reversible interlayer interaction of Zn2+\ ions with the functional moieties in the adjacent layers of COF (-182.0 kcal mol-1). Notably, due to the well-defined nanopores and structural organization, a constructed full cell, displays a discharge capacity as high as 276 mA h g-1\ at a current rate of 125 mA g-1.

}, doi = {10.1039/C9SC03052B}, author = {Mohammed, Abdul Khayum and Ghosh, Meena and Vijayakumar, Vidyanand and Halder, Arjun and Nurhuda, Maryam and Kumar, Sushil and Addicoat, Matthew and Kurungot, Sreekumar and Banerjee, Rahul} } @article {46783, title = {Co (9) S (8) nanoparticle-supported nitrogen-doped carbon as a robust catalyst for oxygen reduction reaction in both acidic and alkaline conditions}, journal = {ChemElectroChem}, volume = {7}, year = {2020}, month = {JUL}, pages = {3123-3134}, type = {Article}, abstract = {

The present work illustrates the synthesis of an efficient and durable catalyst for electrochemical oxygen reduction reaction (ORR) which is active both in the alkaline and acidic conditions by dispersing few-layer graphitic carbon coated Co(9)S(8)nanoparticles on the nitrogen-doped carbon (NVC-G) support (Co9S8/NVC-G). The size of the Co(9)S(8)nanoparticles is nearly 7-8 nm and the particles are found to be dispersed homogeneously on the NVC-G support. The few-layer graphitic carbon formed on the surface of Co(9)S(8)nanoparticles is assisting to accomplish their small size and it also prevents agglomeration of the nanoparticles. The ORR activity of the obtained material was analyzed in both 0.1 M KOH and 0.5 M H(2)SO(4)solutions. Co9S8/NVC-G displays nearly 70 mV overpotential compared to thestate-of-the-artPt/C in 0.1 M KOH solution. The half-wave potential (E-1/2) difference of the present system is nearly 75 mV with the commercial Pt/C. Co9S8/NVC-G displays promising ORR activity in the acidic conditions as well with nearly 140 mV overpotential compared to its Pt/C counterpart. The system shows about 170 mV lowerE(1/2)value with Pt/C. The system shows good stability both in acidic and basic conditions compared to the Pt/C system. Finally, testing of a single cell of a polymer electrolyte membrane fuel cell (PEMFC) was performed by employing Co9S8/NVC-G as the cathode catalyst and Nafion-212 as the proton exchange membrane. The system displays a maximum power density of 245 mW cm(-2)in H-2-O(2)and 115 mW cm(-2)in H-2-air feeding conditions.

}, keywords = {cobalt sulfide, fuel cells, Nanoparticles, nitrogen-doped carbon, oxygen reduction reaction}, issn = {2196-0216}, doi = {10.1002/celc.202000786}, author = {Illathvalappil, Rajith and Kurungot, Sreekumar} } @article {46853, title = {Co@CoAl-layered double hydroxide/nitrogen-doped graphene composite catalyst for Al-H2O-based batteries: simultaneous hydrogen production and electricity generation}, journal = {ChemElectroChem}, volume = {7}, year = {2020}, month = {JUN}, pages = {2582-2591}, type = {Article}, abstract = {

Currently, the low energy efficiency of water electrolysis has compelled research toward the development of novel and energy-effective strategies for low-cost H-2 generation. In this context, we report a new concept of simultaneous H-2 and electricity generation by separating out the exothermic self-sustained Al-H2O reaction via electrochemistry. In addition, to catalyze the cathodic water reduction reaction, a single-pot and environmentally benign synthesis method is adopted. It results in the design of an electrocatalyst composed of Co@CoAl-layered double hydroxide core-shell nanospheres anchored over in situ generated N-doped graphene. Toward the water reduction reaction, the designed catalyst shows a negative voltage shift of mere around 113 mV with respect to the commercial Pt/C catalyst to reach the benchmark 10 mA cm(-2), with excellent stability of approximately 86 \% voltage retention after 12 h of continuous operation. The catalytic superiority of our material is evident when taken for battery-level testing; the fabricated device was able to deliver an average output voltage of around 0.95 V at a discharge current density of 5 mA cm(-2) along with H-2 liberation, which was also detected and quantified through gas chromatography.

}, keywords = {Al-H2O fuel cells, chronopotentiometry, core-shell structures, hydrogen evolution reaction, layered double hydroxides}, issn = {2196-0216}, doi = {10.1002/celc.202000502, Early Access Date = MAY 2020}, author = {Nadeema, Ayasha and Pandurang Kharabe, Geeta and Prakash Biswal, Dibya and Kurungot, Sreekumar} } @article {47006, title = {Dioxolanone-anchored poly(allyl ether)-based cross-linked dual-salt polymer electrolytes for high-voltage lithium metal batteries}, journal = {ACS Applied Materials \& Interfaces}, volume = {12}, year = {2020}, month = {JAN }, pages = {567-579}, type = {Article}, abstract = {

Novel cross-linked polymer electrolytes (XPEs) are synthesized by free-radical copolymerization induced by ultraviolet (UV)-light irradiation of a reactive solution, which is composed of a difunctional poly(ethylene glycol) diallyl ether oligomer (PEGDAE), a monofunctional reactive diluent 4-vinyl-1,3-dioxolan-2-one (VEC), and a stock solution containing lithium salt (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI) in a carbonate-free nonvolatile plasticizer, poly(ethylene glycol) dimethyl ether (PEGDME). The resulting polymer matrix can be represented as a linear polyethylene chain functionalized with cyclic carbonate (dioxolanone) moieties and cross-linked by ethylene oxide units. A series of XPEs are prepared by varying the [O]/[Li] ratio (24 to 3) of the stock solution and thoroughly characterized using physicochemical (thermogravimetric analysis-mass spectrometry, differential scanning calorimetry, NMR, etc.) and electrochemical techniques. In addition, quantum chemical calculations are performed to elucidate the correlation between the electrochemical oxidation potential and the lithium ion-ethylene oxide coordination in the stock solution. Later, lithium bis(fluorosulfonyl)imide (LiFSI) salt is incorporated into the electrolyte system to produce a dual-salt XPE that exhibits improved electrochemical performance, a stable interface against lithium metal, and enhanced physical and chemical characteristics to be employed against high-voltage cathodes. The XPE membranes demonstrated excellent resistance against lithium dendrite growth even after reversibly plating and stripping lithium ions for more than 1000 h with a total capacity of 0.5 mAh cm(-2). Finally, the XPE films are assembled in a lab-scale lithium metal battery configuration by using carbon-coated LiFePO4 (LFP) or LiNi0.8Co0.15Al0.05O2 (NCA) as a cathode and galvanostatically cycled at 20, 40, and 60 degrees C. Remarkably, at 20 degrees C, the NCA-based lithium metal cells displayed excellent cycling stability and good capacity retention (\>50\%) even after 1000 cycles.

}, keywords = {cross-linked polymer electrolyte, dual-salt electrolyte, high-voltage cathode, lithium metal battery, solvent-free photopolymerization}, issn = {1944-8244}, doi = {10.1021/acsami.9b16348}, author = {Vijayakumar, Vidyanand and Diddens, Diddo and Heuer, Andreas and Kurungot, Sreekumar and Winter, Martin and Nair, Jijeesh Ravi} } @article {46911, title = {Fe3+ stabilized 3D cross-linked glycine-melamine formaldehyde networks as precursor for highly efficient oxygen reduction catalyst in alkaline media}, journal = {Materials Letters}, volume = {264}, year = {2020}, month = {APR 1}, pages = {127365}, type = {Article}, abstract = {

Development of inexpensive oxygen reduction electrocatalyst with high activity and durability is very important. Herein, iron carbide encapsulated pod-like graphitic carbon structures were prepared by simple pyrolysis involving Fe-glycine complex integrated melamine-formaldehyde resin precursor. The best catalyst among those studied, Fe-Gly 2 MF-C, possessing high degree of graphitization (I-D /I-G = 0.99) and enhanced specific surface area (205 m(2)/g) exhibited the highest ORR activity with a half-wave potential of 0.80 V in alkaline medium through the four-electron reduction pathway. (C) 2020 Elsevier B.V. All rights reserved.

}, keywords = {fuel cell, Graphitic carbon alloy, Iron carbide, ORR}, issn = {0167-577X}, doi = {10.1016/j.matlet.2020.127365}, author = {Kottarathil, Shijina and Illathvalappil, Rajith and Nisa, S. and Sailaja, G. S. and Mohamed, Peer A. and Nair, Balagopal N. and Gopinathan, Anilkumar M. and Kurungot, Sreekumar and Yamaguchi, Takeo and Hareesh, U. S.} } @article {46940, title = {FeNx/FeSx-anchored carbon sheet-carbon nanotube composite electrocatalysts for oxygen reduction}, journal = {ACS Applied Nano Materials}, volume = {3}, year = {2020}, month = {MAR}, pages = {2234-2245}, type = {Article}, abstract = {

Even though various Pt-free electrocatalysts for oxygen reduction reaction (ORR) have been introduced, many of them are found to be active only in alkaline conditions. Considering Nafion, phosphoric acid-doped polybenzimidazole (PBI), and so on as the prominent ionomer membranes, used in the commercially available polymer electrolyte membrane fuel cells (PEMFCs), it becomes important that any development on the Pt-free catalysts should ensure the better ORR performance under acidic conditions. The present work effectively tackles this issue, where an ORR-based catalyst could be prepared with simultaneous incorporation of both Fe-N and Fe-S active sites on in situ generated carbon sheets which are spatially separated by the carbon nanotube (CNT) network. This catalyst shows ability to perform under both acidic and basic conditions. This has been achieved by growing a polyethylenedioxythiophene polymer network in the presence of CNT and melamine followed by its pyrolysis under an inert atmosphere. The catalyst formed at 900 degrees C (PMCNT-900) displays 0.94 V onset potential for ORR under acidic electrolyte conditions, which corresponds to 60 mV overpotential compared to its 40 wt \% Pt/C counterpart. Interestingly, in single cell demonstration of Nafion-based PEMFC with PMCNT-900 as the cathode catalyst, the system delivered a maximum power density (PD) of 500 and 275 mW/cm(2) at 60 degrees C under H-2-O-2 and H-2-air feed conditions, respectively. On the other hand, in a single cell test in the anion exchange membrane fuel cell (AEMFC) mode, a maximum power density of 65 mW/cm(2) at 50 degrees C could be achieved with the same cathode catalyst, which is a comparable value obtained while employing Pt/C as the cathode. These results, thus, infer to the efficiency of the catalyst to facilitate ORR under the extreme pH conditions, and particularly its performance under acidic condition reveals its prospect as a potential Pt-free electrocatalyst to serve in the Nafion-based systems.

}, keywords = {carbon nanotube, electrocatalyst, fuel cell, oxygen reduction reaction, Pt-free ORR}, issn = {2574-0970}, doi = {10.1021/acsanm.9b02335}, author = {Bhange, Siddheshwar N. and Soni, Roby and Singla, Gourav and Ajithkumar, T. G. and Kurungot, Sreekumar} } @article {46845, title = {Hierarchical nanoflower arrays of Co9S8-Ni3S2 on nickel foam: a highly efficient binder-free electrocatalyst for overall water splitting}, journal = {Chemistry-A European Journal}, volume = {26}, year = {2020}, month = {JUN }, pages = {7900-7911}, type = {Article}, abstract = {

Hydrogen production is vital for meeting future energy demands and managing environmental sustainability. Electrolysis of water is considered as the suitable method for H-2 generation in a carbon-free pathway. Herein, the synthesis of highly efficient Co9S8-Ni3S2 based hierarchical nanoflower arrays on nickel foam (NF) is explored through the one-pot hydrothermal method (Co9S8-Ni3S2/NF) for overall water splitting applications. The nanoflower arrays are self-supported on the NF without any binder, possessing the required porosity and structural characteristics. The obtained Co9S8-Ni3S2/NF displays high hydrogen evolution reaction (HER), as well as oxygen evolution reaction (OER), activities in 1 m KOH solution. The overpotentials exhibited by this system at 25 mA cm(-2) are nearly 277 and 102 mV for HER and OER, respectively, in 1 m KOH solution. Subsequently, the overall water splitting was performed in 1 m KOH solution by employing Co9S8-Ni3S2/NF as both the anode and cathode, where the system required only 1.49, 1.60, and 1.69 V to deliver the current densities of 10, 25, and 50 mA cm(-2), respectively. Comparison of the activity of Co9S8-Ni3S2/NF with the state-of-the-art Pt/C and RuO2 coated on NF displays an enhanced performance for Co9S8-Ni3S2/NF both in the half-cell as well as in the full cell, emphasizing the significance of the present work. The post analysis of the material after water electrolysis confirms that the surface Co(OH)(2) formed during the course of the reaction serves as the favorable active sites. Overall, the activity modulation achieved in the present case is attributed to the presence of the open-pore morphology of the as formed nanoflowers of Co9S8-Ni3S2 on NF and the simultaneous presence of the surface Co(OH)(2) along with the highly conducting Co9S8-Ni3S2 core, which facilitates the adsorption of the reactants and subsequently its conversion into the gaseous products during water electrolysis.

}, keywords = {cobalt sulfide, electrocatalysts, Hydrogen evolution, overall water splitting, oxygen evolution}, issn = {0947-6539}, doi = {10.1002/chem.202000839, Early Access Date = MAY 2020}, author = {Illathvalappil, Rajith and Walko, Priyanka S. and Kanheerampockil, Fayis and Bhat, Suresh K. and Devi, R. Nandini and Kurungot, Sreekumar} } @article {46761, title = {In situ cross-linked nonaqueous polymer electrolyte for zinc-metal polymer batteries and hybrid supercapacitors}, journal = {Small}, volume = {16}, year = {2020}, month = {SEP}, pages = {2002528}, type = {Article}, abstract = {

This work reports the facile synthesis of nonaqueous zinc-ion conducting polymer electrolyte (ZIP) membranes using an ultraviolet (UV)-light-induced photopolymerization technique, with room temperature (RT) ionic conductivity values in the order of 10(-3)S cm(-1). The ZIP membranes demonstrate excellent physicochemical and electrochemical properties, including an electrochemical stability window of \>2.4 V versus Zn|Zn(2+)and dendrite-free plating/stripping processes in symmetric Zn||Zn cells. Besides, a UV-polymerization-assisted in situ process is developed to produce ZIP (abbreviated i-ZIP), which is adopted for the first time to fabricate a nonaqueous zinc-metal polymer battery (ZMPB; VOPO4|i-ZIP|Zn) and zinc-metal hybrid polymer supercapacitor (ZMPS; activated carbon|i-ZIP|Zn) cells. The VOPO(4)cathode employed in ZMPB possesses a layered morphology, exhibiting a high average operating voltage of approximate to 1.2 V. As compared to the conventional polymer cell assembling approach using the ex situ process, the in situ process is simple and it enhances the overall electrochemical performance, which enables the widespread intrusion of ZMPBs and ZMPSs into the application domain. Indeed, considering the promising aspects of the proposed ZIP and its easy processability, this work opens up a new direction for the emergence of the zinc-based energy storage technologies.

}, keywords = {nonaqueous electrolytes, polymer electrolytes, postlithium batteries, Supercapacitors, zinc-metal batteries}, issn = {1613-6810}, doi = {10.1002/smll.202002528, Early Access Date = JUL 2020}, author = {Vijayakumar, Vidyanand and Ghosh, Meena and Kurian, Maria and Torris, Arun and Dilwale, Swati and Badiger, V. Manohar and Winter, Martin and Nair, Jijeesh Ravi and Kurungot, Sreekumar} } @article {46898, title = {Nafion lonomer-based single component electrolytes for aqueous Zn/MnO2 batteries with long cycle life}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {8}, year = {2020}, month = {APR }, pages = {5040-5049}, type = {Article}, abstract = {

Recently, aqueous rechargeable Zn/MnO2 batteries are emerging as promising energy storage aids owing to their improved safety, low cost of fabrication, and high energy density. However, the rapid decay of capacity during extended charge- discharge cycles hinders the prospect of this technology beyond lab-scale. In the conventional Zn/MnO2 cell, additives such as Mn2+ have been used to tackle the stability issue. Here, we demonstrate that cycling performance of the Zn/MnO2 cell can be improved substantially by using Nafion ionomer as the separator in combination with zinc-ion conducting electrolytes. The Nafion ionomer-based Zn/MnO2 cells do not require any Mn{\textquoteright} additive in the electrolyte and hence termed as {\textquoteleft}{\textquoteleft}single component{\textquoteright}{\textquoteright} electrolytes. The postmortem study of the post-cycled electrodes reveals that the structural evolution of both the anode and cathode in various electrolytes (1 M Zn(CF3SO3)(2), 1 M ZnSO4 center dot 7H(2)O, and 3 M ZnSO4 center dot 7H(2)O) during prolonged cycling significantly influences the cycle life of the respective cells. Optimizing the Nafion ionomer membrane with a suitable electrolyte could render the desired combination of high capacity and high cycle life for a Zn/MnO2 cell.

}, keywords = {aqueous Zn-ion batteries, Cycling stability, dendrite suppression, Electrodeposition, MnO2, Nafion ionomer separator, single component electrolyte}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.9b06798}, author = {Ghosh, Meena and Vijayakumar, Vidyanand and Anothumakkool, Bihag and Kurungot, Sreekumar} } @article {46903, title = {NiFe layered double hydroxide-decorated N-doped entangled-graphene framework: a robust water oxidation electrocatalyst}, journal = {Nanoscale Advances}, volume = {2}, year = {2020}, month = {APR }, pages = {1709-1717}, type = {Article}, abstract = {

Three dimensional (3D) porous carbon materials are highly desirable for electrochemical applications owing to their high surface area and porosity. Uniformly distributed porosity in the 3D architecture of carbon support materials allows reactant molecules to access more electrochemically active centres and simultaneously facilitate removal of the product formed during electrochemical reactions. Herein, we have prepared a nitrogen-doped entangled graphene framework (NEGF), decorated with NiFe-LDH nanostructures by an in situ solvothermal method followed by freeze-drying at high vacuum pressure and low temperature. The freeze-drying method helped to prevent the restacking of the graphene sheets and the formation of a high surface area nitrogen-doped entangled graphene framework (NEGF) supported NiFe-LDHs. The incorporation of the NEGF has significantly reduced the overpotential for the electrochemical oxygen evolution reaction (OER) in 1 M KOH solution. This corresponds to an overpotential reduction from 340 mV for NiFe-LDHs to 290 mV for NiFe-LDH/NEGF to reach the benchmark current density of 10 mA cm(-2). The preparation of the catalyst is conceived through a low-temperature scalable process.

}, issn = {2516-0230}, doi = {10.1039/c9na00808j}, author = {Manna, Narugopal and Ayasha, Nadeema and Singh, Santosh K. and Kurungot, Sreekumar} } @article {46840, title = {Porphyrin-based conducting polymer hydrogel for supercapacitor application}, journal = {Energy Technology}, volume = {8}, year = {2020}, month = {JUN}, pages = {2000061}, type = {Article}, abstract = {

Herein, the electrochemical properties and energy storage capability of a flexible, all-solid-state supercapacitor based on the supramolecular assembly of polypyrrole (PPy) and the anion of 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine manganese(III) chloride (MnTSPP) are reported. The electrode material consists of a conductive polymer hydrogel formed through the gelation initiated by cross-linking of the dopant MnTSPP anion in the PPy chains. The morphology of the cross-linked polymer hydrogel is that of a particle-decorated nanofiber, which can perform as a flexible supercapacitor electrode material with a specific capacitance of 300 Fg(-1) and capacitance retention of 78\% up to 10 000 cycles. The anion of MnTSPP plays a pivotal role in enhancing the charge storage capability by facilitating the electron transfer between the polymer interchains. In addition, the steric hindrance due to the large size of the dopant counter ions of MnTSPP reduces the counterion drain effect and structural pulverization of PPy, thereby improving the capacitive retention.

}, keywords = {conductive hydrogels, energy storage devices, Flexible Supercapacitors, nanofibers, porphyrin-based polymers}, issn = {2194-4288}, doi = {10.1002/ente.202000061}, author = {Das, Debasree and Kurungot, Sreekumar} } @article {46777, title = {Role of B site ions in bifunctional oxygen electrocatalysis: a structure-property correlation study on doped Ca(2)Fe(2)O(5)brownmillerites}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, year = {2020}, month = {JUL }, pages = {15520-15527}, type = {Article}, abstract = {

The role of B site doping with transition metals in brownmillerites, a perovskite related family of compounds, in bifunctional oxygen electrocatalysis,viz., simultaneous reduction and evolution reactions, is analysed. Ca2Fe1.9M0.1O5(M = Mn, Co, Ni, and Cu) is synthesised and structurally characterised by powder XRD and Rietveld refinement. Valence states of the surface B site ions are identified by X-ray photoelectron spectroscopy. Bifunctional oxygen electrochemistry is studied with the RDE and RRDE techniques and correlated with the structural and electronic parameters like oxygen non-stoichiometry and B site catalytic activity. Since the widely accepted electronic descriptors like e(g)filling may not be sufficient for explaining the bifunctional activity, B site electron donating capability as well as the extent of oxygen vacancies enhancing O(2)adsorption is also considered. Such structural parameters are also found to influence both the ORR and OER and based on this, Ni doping is proposed as advantageous for the bifunctional activity.

}, issn = {1463-9076}, doi = {10.1039/d0cp02391d}, author = {Thundiyil, Shibin and Vinod, C. P. and Kurungot, Sreekumar and Devi, R. Nandini} } @article {46664, title = {Scalable synthesis of manganese-doped hydrated vanadium oxide as a cathode material for aqueous zinc-metal battery}, journal = {ACS Applied Materials \& Interfaces}, volume = {12}, year = {2020}, month = {OCT }, pages = {48542-48552}, type = {Article}, abstract = {

Rechargeable aqueous zinc-metal batteries (ZMBs) are considered as potential energy storage devices for stationary applications. Despite the significant developments in recent years, the performance of ZMBs is still limited due to the lack of advanced cathode materials delivering high capacity and long cycle life. In this work, we report a low-temperature and scalable synthesis method following a surfactant-assisted route for preparing manganese-doped hydrated vanadium oxide (MnHVO-30) and its application as the cathode material for ZMB. The as-prepared material possesses a porous architecture and expanded interlayer spacing. Therefore, the MnHVO-30 cathode offers fast and reversible insertion of Zn2+ ions during the charge/discharge process and delivers 341 mAh g(-1) capacity at 0.1 A g(-1). Moreover, the MnHVO-30 parallel to Zn cell retains 82\% of its initial capacity over 1200 stability cycles, which is higher compared to that of the undoped system. Besides, a quasi-solid-state home-made pouch cell with an area of 3.3 x 1.6 cm(2) and 3.6 mg cm(-2) loading is assembled, achieving 115 mAh g(-1) capacity over 100 stability cycles. Therefore, this work provides an easy and attractive way for preparing efficient cathode materials for aqueous ZMBs.

}, keywords = {anionic surfactant, hydrated vanadium pentoxide, Nafion ionomer membrane, post-lithium battery, quasi-solid-state battery}, issn = {1944-8244}, doi = {10.1021/acsami.0c13221}, author = {Ghosh, Meena and Dilwale, Swati and Vijayakumar, Vidyanand and Kurungot, Sreekumar} } @article {46770, title = {Template assisted synthesis of Ni,N co-doped porous carbon from Ni incorporated ZIF-8 frameworks for electrocatalytic oxygen reduction reaction}, journal = {New Journal of Chemistry}, volume = {44}, year = {2020}, month = {JUL }, pages = {12343-12354}, type = {Article}, abstract = {

A heteroatom doped porous carbon electrocatalyst with enhanced oxygen reduction reaction (ORR) performance in alkaline medium was obtained by high temperature treatment of Ni incorporated ZIF-8 frameworks and its composite with g-C(3)N(4)as a supporting matrix template. The morphology and porosity of this heteroatom containing carbon were tuned by varying the Ni : Zn molar ratio in Ni/Zn ZIF-8 and Ni/Zn ZIF-8@g-C(3)N(4)composites. The template aided synthetic strategy using g-C(3)N(4)helped in the controlled decomposition of composites leading to a heteroporous sheet like architecture with increased nitrogen content. The Ni/Zn ZIF-8 sample on heat treatment in the 800-1000 degrees C temperature range led to the formation of Ni,N co-doped porous carbon (Ni-NPC) with Ni-C active sites. The defective sites induced by nickel carbide along with the distributed N atoms on the carbon surface enabled active O(2)adsorption sites. The high surface area, high degree of graphitisation as well as the defects created by well dispersed N and Ni on porous carbon matrices favoured charge separation leading to higher electrochemical ORR activity. The Ni,N co-doped carbon catalyst in alkaline medium exhibited a limiting current density of 5.2 mA cm(-2)with a half-wave potential of 0.76 Vvs.RHE in 0.1 M KOH. The catalyst also showed improved methanol tolerance and better stability compared to the standard Pt/C catalyst.

}, issn = {1144-0546}, doi = {10.1039/d0nj01373k}, author = {Priya K., Vaishna and Thomas, Minju and Illathvalappil, Rajith and K., Shijina and Kurungot, Sreekumar and Nair, Balagopal N. and Mohamed, A. Peer and Anilkumar, Gopinathan M. and Yamaguchi, Takeo and Hareesh, U. S.} } @article {46970, title = {WO3 nanorods bearing interconnected Pt nanoparticle units as an activity-modulated and corrosion-resistant carbon-free system for polymer electrolyte membrane fuel cells}, journal = {ACS Applied Energy Materials}, volume = {3}, year = {2020}, month = {FEB}, pages = {1908-1921}, type = {Article}, abstract = {

Commercial platinum-supported carbon (Pt/C) catalyst is the most widely used oxygen reduction reaction (ORR) electrocatalyst in polymer electrolyte membrane fuel cells (PEMFCs). However, carbon oxidation in Pt/C during the operation of PEMFCs poses serious issues, particularly in meeting long-term durability of the cells. Although carbon-free Pt-based catalysts are considered to be the best alternatives, the single-cell performances reported for many such systems are found to be inferior to that of the carbon-based systems. As a practical way to realize a carbon-free electrocatalyst, we have developed a system by dispersing an interconnected Pt nanoparticle network on the nanorods of tungsten oxide (WO3). Uniform dispersion of the WO3 nanorods by fine and more or less interconnected Pt nanoparticles (20 wt \%) is a key feature of the electrocatalyst. This has helped the system to achieve an intrinsic ORR characteristics which is very similar to that of Pt/C, as reflected from the comparative analysis of the onset potential, half-wave potential, limiting current density, and the number of electrons transferred in the ORR process. Pt/WO3 also shows better stability under start-stop accelerated potential cycling after 10 000 cycles, compared to Pt/C. The relative decrement in the electrochemically active surface area (ECSA) for Pt/WO3 nanorods was negligible, compared to the similar to 26\% decrement registered by Pt/C under the identical testing conditions. Finally, a system-level validation in a single-cell model of PEMFC by fabricating a membrane electrode assembly (MEA) with Pt/WO3 as both the anode and cathode catalyst delivered comparable output power density as that of a similar system fabricated by using Pt/C. ECSA comparison in MEA shows the potential use of Pt/WO3-400 as the catalyst for the fuel cells, since it is exhibiting an ECSA value that is 3.4 greater than that of Pt/C at a Pt loading of 0.5 mg cm(-2).

}, keywords = {Carbon-free, electrocatalyst, fuel cell, oxygen reduction reaction, tungsten oxide}, issn = {2574-0962}, doi = {10.1021/acsaem.9b02333}, author = {Kumar, Sachin and Bhange, Siddheshwar N. and Soni, Roby and Kurungot, Sreekumar} } @article {47434, title = {Biomass-derived activated carbon material from native European deciduous trees as an inexpensive and sustainable energy material for supercapacitor application}, journal = {Journal of Energy Storage}, volume = {34}, year = {2021}, month = {FEB}, pages = {102178}, type = {Article}, abstract = {

Activated carbons are one of the possible electrode materials for supercapacitors (SCs), which are widely used in commercial applications. Herein, we reported the synthesis of a novel activated carbon derived through a cavitation process from the mixture of native European deciduous trees, Birch, Fagaceae, and Carpinus betulus (commonly known as European hornbeam), which was employed as the electrode material in SC. From the morphological and structural characterization, we observed that the prepared sample is a desirable carbon with good porosity and high specific surface area of about 614 m(2) g(-1). The electrochemical properties of the synthesized material were evaluated with a three-electrode configuration in 1.0 M H2SO4 electrolyte. It was found that in device mode, the carbon material delivers a specific capacitance of 24 F g(-1) at 0.25 A g(-1) with excellent cycling stability of over 10000 consecutive charge/discharge cycles. Thus, our studies demonstrate the facile synthesis of biomass-derived carbon and its application as a versatile electrode material for SC applications.

}, keywords = {Biomass, Carbon material, Deciduous trees, Electrode material, supercapacitor}, issn = {2352-152X}, doi = {10.1016/j.est.2020.102178}, author = {Jain, Amrita and Ghosh, Meena and Krajewski, Marcin and Kurungot, Sreekumar and Michalska, Monika} } @article {47110, title = {Efficient electrochemical oxygen reduction to hydrogen peroxide by transition metal-doped silicate Sr0.7Na0.3SiO3-delta}, journal = {ACS Applied Materials \& Interfaces}, volume = {13}, year = {2021}, month = {JAN}, pages = {382-390}, type = {Article}, abstract = {

Electrochemical oxygen reduction in a selective two-electron pathway is an efficient method for onsite production of H2O2. State of the art noble metal-based catalysts will be prohibitive for widespread applications, and hence earth-abundant oxide-based systems are most desired. Here we report transition metal (Mn, Fe, Ni, Cu)-doped silicates, Sr0.7Na0.3SiO3-delta, as potential electrocatalysts for oxygen reduction to H2O2 in alkaline conditions. These novel compounds are isostructural with the parent Sr0.7Na0.3SiO3-delta and crystallize in monoclinic structure with corner-shared SiO4 groups forming cyclic trimers. The presence of Na stabilizes O vacancies created on doping, and the transition metal ions provide catalytically active sites. Electrochemical parameters estimated from Tafel and Koutechy-Levich plots suggest a two-electron transfer mechanism, indicating peroxide formation. This is confirmed by the rotating ring disc electrode method, and peroxide selectivity and Faradaic efficiency are calculated to be in the range of 65-82\% and 50-68\%, respectively, in a potential window 0.3 to 0.6 V (vs RHE). Of all the dopants, Ni imparts the maximum selectivity and efficiency as well as highest rate of formation of H2O2 at 1.65 mu mol s(-1).

}, keywords = {H2O2, mixed metal oxide, ORR, silicate}, issn = {1944-8244}, doi = {10.1021/acsami.0c16311}, author = {Thundiyil, Shibin and Kurungot, Sreekumar and Devi, R. Nandini} } @article {47029, title = {Enhanced electrocatalytic activity of PtRu/nitrogen and sulphur co-doped crumbled graphene in acid and alkaline media}, journal = {Journal of Colloid and Interface Science}, volume = {590}, year = {2021}, month = {MAY }, pages = {154-163}, type = {Article}, abstract = {

The low mass activity and high price of pure platinum (Pt)-based catalysts predominantly limit their large-scale utilization in electrocatalysis. Therefore, the reduction of Pt amount while preserving the electrocatalytic efficiency represents a viable alternative. In this work, we prepared new PtRu2 nanoparticles supported on sulphur and nitrogen co-doped crumbled graphene with trace amounts of iron (PtRu2/PF) electrocatalysts. The PtRu2/PF catalysts exhibited enhanced electrocatalytic performance and stability for the hydrogen evolution reaction (HER) at pH = 0. Moreover, the prepared PtRu2/PF electrocatalyst displayed higher HER activity than commercial 20\% Pt/C. The PtRu2/PF catalyst achieved a current density of 10 mA cm(-2) at an overpotential value of only 22 mV for HER, performing better activity than many other Pt-based electrocatalysts. Besides, the PtRu2/PF revealed a good performance for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline media. The PtRu2/PF catalyst recorded a current density of 10 mA cm(-2) at an overpotential of only 270 mV for OER in KOH (1.0 M) solution and an onset potential of 0.96 V vs. RHE (at 1 mA cm(-2)) for ORR in KOH (0.1 M) solution. (C) 2021 Elsevier Inc. All rights reserved.

}, keywords = {HER, OER, ORR, PtRu2, Sulphur and nitrogen co-doped crumbled graphene}, issn = {0021-9797}, doi = {10.1016/j.jcis.2021.01.049}, author = {Pang, Liuqing and Miao, Yuanyuan and Bhange, Siddheshwar N. and Barras, Alexandre and Addad, Ahmed and Roussel, Pascal and Amin, Mohammed A. and Kurungot, Sreekumar and Szunerits, Sabine and Boukherroub, Rabah} } @article {47052, title = {Facile synthesis of CNT interconnected PVP-ZIF-8 derived hierarchically porous Zn/N co-doped carbon frameworks for oxygen reduction dagger}, journal = {Nanoscale}, volume = {13}, year = {2021}, month = {MAR}, pages = {6248-6258}, type = {Article}, abstract = {

In this work, a strategy has been adopted to construct an architecture through the coordination of polyvinylpyrrolidone (PVP) and a monodisperse zeolitic imidazolate framework (ZIF-8), which was entwined by carbon nanotubes (CNTs) firstly, followed by a pyrolysis process to obtain the hybrid catalyst. The meticulous design of the hybrid material using CNTs to interconnect the PVP assisted ZIF-8 derived porous carbon frameworks together produces a hierarchical pore structure and dual-heteroatom (Zn/N) doping (Zn-N/PC@CNT). Without further acid treatment, the hybrid material prepared after pyrolysis at 900 degrees C (PVP-ZIF-8@CNT-900) has been demonstrated as an efficient non-precious metal catalyst for the oxygen reduction reaction (ORR) with its superior stability compared to the commercial 20 wt\% Pt/C catalyst in alkaline media. The catalyst shows better performance towards the ORR, with its more positive onset and half-wave potentials (E-onset = 0.960 V vs. RHE and E-1/2 = 0.795 V vs. RHE) than the counterpart system which is free of both CNT and PVP. The high performance of the hybrid catalyst can be ascribed to the co-existence of dual-active sites with hierarchical pore structures originating from the synergistic effects between Zn/N co-doped porous carbon and CNTs. We further demonstrated the single-cell performance by using the homemade system as the cathode catalyst for the Alkaline Exchange Membrane Fuel Cell (AEMFC) system, which showed a maximum power density of 45 mW cm(-2) compared to 60 mW cm(-2) obtained from the 40 wt\% Pt/C catalyst.

}, issn = {2040-3364}, doi = {10.1039/d0nr09156a, Early Access Date = FEB 2021}, author = {Singla, Gourav and Bhange, Siddheshwar N. and Mahajan, Mani and Kurungot, Sreekumar} } @article {47665, title = {High-voltage non-aqueous hybrid supercapacitor based on the N2200 polymer supported over multiwalled carbon nanotubes}, journal = {Nanoscale}, volume = {13}, year = {2021}, month = {JUL}, pages = {12314-12326}, type = {Article}, abstract = {P(NDI2OD-T2), also known as Polyera ActivInk N2200, is a widely accepted non-fullerene acceptor polymer that is used prominently in the energy harvesting application due to its ease of synthesis, high electron mobility, and other desirable semiconducting properties. With its recent foray into energy storage applications, there is tremendous potential for developing composites of N2200 with carbon nanotubes (CNTs) to improve its electrical properties and extend its applicability. Here we report a facile synthesis of an N2200 composite with multiwalled carbon nanotubes (MWCNTs) following an in situ approach to include MWCNTs into the polymer matrix, improving its electrochemical performance in an organic electrolyte (1 M LiClO4/propylene carbonate). The composite material with an optimum MWCNT content exhibits prominent redox behavior delivering a specific capacity of 80 mA h g((polymer))(-1) in a standard three-electrode cell. Moreover, the N2200/MWCNT composite material showing a battery-type electrochemical signature could perform as an efficient negative electrode in a high-voltage (2.4 V) hybrid supercapacitor device comprising capacitive activated carbon as the positive electrode.}, issn = {2040-3364}, doi = {10.1039/d1nr01422f}, author = {Wavhal, Bhaiyyasaheb Anurath and Ghosh, Meena and Sharma, Sandeep and Kurungot, Sreekumar and Asha, S. K.} } @article {47432, title = {In situ polymerization process: an essential design tool for lithium polymer batteries dagger}, journal = {Energy \& Environmental Science}, volume = {14}, year = {2021}, month = {MAY }, pages = {2708-2788}, type = {Review}, abstract = {

Polymer electrolytes (PEs), a type of solid-state electrolytes (SSEs), have been in contention for nearly half a century to replace organic liquid electrolytes (LEs) that are used in state-of-the-art lithium-ion batteries (LIBs). They are envisaged to accelerate the industrial-scale production of safe, energy-dense, flexible, and thin lithium polymer batteries (LPBs). LPBs are expected to be widely employed for electric propulsion and other futuristic applications, such as flexible electronics and the Internet of Things (IoT). Even though several polymer architectures and chemistries have been attempted so far, PEs that can outperform LEs remain a real challenge. Apart from inadequate Li+-ion transport properties, challenges concerning the integration of PEs and the engineering of compatible, robust, and durable interfaces and interphases at both the electrodes of LPBs must be appropriately addressed. Recently, the in situ polymerization process has been widely employed as a robust fabrication tool for surpassing the intricacies related to the integration of PEs in LPBs. Hence, in this review, we focus on the in situ polymerization processes that employ various polymerization methods (e.g., free-radical polymerization, ionic polymerization, electropolymerization, condensation polymerization, etc.), functional monomers and oligomers (e.g., acrylate, methacrylate, allyl and vinyl ethers, epoxides, etc.), and PE integration strategies for the fabrication of lithium (ion and metal) polymer batteries (LIPBs and LMPBs). Additionally, this review also evaluates the approaches that have been developed until now to implement the in situ processing of LPBs from large-sized pouch cells to flexible-/printable-batteries and even microbatteries.

}, issn = {1754-5692}, doi = {10.1039/d0ee03527k, Early Access Date = FEB 2021}, author = {Vijayakumar, Vidyanand and Anothumakkool, Bihag and Kurungot, Sreekumar and Winter, Martin and Nair, Jijeesh Ravi} } @article {46766, title = {In situ preparation of ionomer as a tool for triple-phase boundary enhancement in 3D graphene supported Pt catalyst}, journal = {Advanced Sustainable Systems}, volume = {5}, year = {2021}, month = {JAN}, pages = {2000125}, type = {Article}, abstract = {

For improving the performance of platinum electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs), it is important to enhance the Pt utilization level in the catalyst systems. A high performing electrocatalyst (Pt/3DNG) is developed for PEMFC applications by using nitrogen-doped 3D graphene (3DNG) as the support material and an in situ grafted active {\textquoteleft}{\textquoteleft}triple-phase boundary{\textquoteright}{\textquoteright} to more precisely control the formation of the proton conducting ionomer interface at the active sites. Considering the 3D morphology of the system, during the electrode fabrication for realistic single-cell evaluation, the concept of in situ generation of the proton conducting-ionomer based {\textquoteleft}{\textquoteleft}active triple-phase boundary{\textquoteright}{\textquoteright} is introduced, which could potentially replace the conventional method of using Nafion ionomer for the electrode preparation. The monomers owing to their small-size can access the pores and inner regions of the 3DNG support, which on UV-curing, undergo polymerization and transform into an ionomer with an extended interfacial network into the nanoregimes of 3DNG. Single cell evaluation of the membrane electrode assembly in a high-temperature PEMFC by using phosphoric acid doped polybenzimidazole membrane demonstrates the utility of the present strategy.

}, keywords = {electrocatalysts, fuel cells, graphene, oxygen reduction reaction}, issn = {2366-7486}, doi = {10.1002/adsu.202000125, Early Access Date = JUL 2020}, author = {Gangadharan, Pranav K. and Vijayakumar, Vidyanand and Nediyirakkal, Shijil A. and Fernandez, Roshni Tresa and Siddharthan, V. Adhrika and Kurungot, Sreekumar} } @article {47120, title = {Interconnected polyaniline nanostructures: enhanced interface for better supercapacitance retention}, journal = {Polymer}, volume = {212}, year = {2021}, month = {JAN }, pages = {123169}, type = {Article}, abstract = {

Polyaniline and its nanocomposites have emerged as desirable electrode materials for supercapacitors. However, achieving specific capacitance with long-term cyclic stability is still a challenge. The present study reports on novel hierarchically porous and cross-linked polyaniline synthesized by a method employing aniline (monomer) and phytic acid (dopant acid) in the presence of octyltrimethyl ammonium bromide (OTAB) surfactant. The electrochemical performance of the phytic acid doped sample has been compared with HCl doped samples, the former being superior, i.e., a specific capacitance of 523 and 325 F g(-1) at current densities of 0.25 and 10 A g(-1), respectively. Additionally, the same possess excellent cycling stability with retention of similar to 88\% of its initial capacitance over 10,000 charge-discharge cycles. Further, the phytic acid doped sample exhibited a lower equivalent series resistance (0.98 Omega cm(2)) than the HCl doped sample (1.26 Omega cm(2)). These results reveal the capability of the phytic acid doped hierarchical polyaniline sample as a promising active material for electrochemical applications.

}, keywords = {Cyclic stability, Hierarchical polyaniline, Supercapacitance retention}, issn = {0032-3861}, doi = {10.1016/j.polymer.2020.123169}, author = {Mooss, Vandana A. and Vijayakumar, Vidyanand and Kurungot, Sreekumar and Athawale, Anjali A.} } @article {47419, title = {Naphthalene dianhydride organic anode for a {\textquoteleft}rocking-chair{\textquoteright} zinc-proton hybrid ion battery}, journal = {Dalton Transactions}, volume = {50}, year = {2021}, month = {MAR }, pages = {4237-4243}, type = {Article}, abstract = {

Rechargeable batteries consisting of a Zn metal anode and a suitable cathode coupled with a Zn2+ ion-conducting electrolyte are recently emerging as promising energy storage devices for stationary applications. However, the formation of high surface area Zn (HSAZ) architectures on the metallic Zn anode deteriorates their performance upon prolonged cycling. In this work, we demonstrate the application of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), an organic compound, as a replacement for the Zn-metal anode enabling the design of a {\textquoteleft}rocking-chair{\textquoteright} zinc-proton hybrid ion battery. The NTCDA electrode material displays a multi-plateau redox behaviour, delivering a specific discharge capacity of 143 mA h g(-1) in the potential window of 1.4 V to 0.3 V vs. Zn|Zn2+. The detailed electrochemical characterization of NTCDA in various electrolytes (an aqueous solution of 1 M ZnOTF, an aqueous solution of 0.01 M H2SO4, and an organic electrolyte of 0.5 M ZnOTF/acetonitrile) reveals that the redox processes leading to charge storage involve a contribution from both H+ and Zn2+. The performance of NTCDA as an anode is further demonstrated by pairing it with a MnO2 cathode, and the resulting MnO2||NTCDA full-cell (zinc-proton hybrid ion battery) delivers a specific discharge capacity of 41 mA h g(total)(-1) (normalized with the total mass-loading of both anode and cathode active materials) with an average operating voltage of 0.80 V.

}, issn = {1477-9226}, doi = {10.1039/d0dt04404k}, author = {Ghosh, Meena and Vijayakumar, Vidyanand and Kurian, Maria and Dilwale, Swati and Kurungot, Sreekumar} } @article {47725, title = {PdP/WO3 multi-functional catalyst with high activity and stability for direct liquid fuel cells (DLFCs)}, journal = {Sustainable Energy \& Fuels}, volume = {5}, year = {2021}, month = {SEP}, pages = {4758-4770}, type = {Article}, abstract = {Direct liquid fuel cells are energy conversion devices which utilize formate and methanol as fuels. These systems are relieved of the problem of H-2 transport and storage, making them highly desirable for various practical applications. However, the low stability and activity of carbon supported catalysts such as Pt/C both in the anode and cathode is a critical hindering factor towards their further development. As a practical solution to overcome this issue, in this work, we report on the development of phosphorus-doped palladium (PdP) nanoparticle-supported tungsten oxide (WO3) nanorods (PdP/WO3) as a versatile multifunctional catalyst for facilitating the oxidation of formate and methanol in the anode and the oxygen reduction reaction (ORR) in the cathode. Strong metal-support interactions and electronic modifications incurred by the doped phosphorus help this system to achieve desirable properties to enable it to effectively function both for the anode and cathode applications. PdP/WO3 showed 16-times higher mass activity compared to Pt/C even after 3000 start/stop cycles for the ORR. For formate and methanol oxidation, PdP/WO3 exhibited current densities of 0.50 and 0.734 A mg(Pd)(-1), respectively, outperforming the state-of-the-art catalysts. With these bifunctional features, PdP/WO3 stands out as a potential system to be used as an anode and cathode catalyst in direct liquid fuel cells, all the while offering an opportunity for the development of carbon-free electrocatalysts.}, issn = {2398-4902}, doi = {10.1039/d1se00584g}, author = {Kumar, Sachin and Soni, Roby and Kurungot, Sreekumar} } @article {47674, title = {Seed-mediated growth of Pt on high-index faceted Au nanocrystals: the ag lining and implications for electrocatalysis}, journal = {ACS Applied Nano Materials}, volume = {4}, year = {2021}, month = {SEP }, pages = {9155-9166}, type = {Article}, abstract = {Bimetallic Au@Pt nanocrystals (NCs) offer a unique combination of plasmonic and catalytic properties and are a growing field of research. Herein, we report an unusual observation in the behavior of silver ions (Ag+) which was found to play a dominant role in dictating the Pt deposition in a seed-mediated growth method. {\textquoteleft}While the literature is replete with various instances of Ag-assisted Pt deposition whereby higher concentration of Ag+ translates into a thicker Pt shell, in the present study, contradictory observations were made. In the presence of lower amounts of Ag+, thick Pt shells were visualized, while at higher concentrations of Ag+, the extent of Pt deposition via the galvanic replacement reaction was reduced. Additionally, the presence of Ag was deemed necessary for the Pt deposition to take place, either in the form of an underpotential deposition layer on the Au NCs or by introducing Ag+ in the growth solution. We have demonstrated our findings on two different Au NCs enclosed with high-index facets, concave cuboid, and elongated tetrahexahedra, which mirror similar observations and provide generality to our claim. To the best of our knowledge, the time required for Pt deposition on the Au core in the present work is the least among the reported seed-mediated routes. Furthermore, this work, besides presenting a facile and general route for the amalgamation of catalytic and plasmonic properties in hybrid Pt-Au NCs, sheds light on the mechanistic aspects of Ag-assisted wet-chemical generation of bimetallic Au@Pt NCs. The overall electrocatalytic performance of our Au@Pt NCs toward the oxygen reduction reaction was realized to be impressive.}, keywords = {bimetallic nanostructure, galvanic replacement reaction, high-index facet, oxygen reduction reaction, seed-mediated growth, underpotential deposition}, doi = {10.1021/acsanm.1c01714}, author = {Roy, Debashree and Rajendra, Ranguwar and Gangadharan, Pranav K. and Pandikassala, Ajmal and Kurungot, Sreekumar and Ballav, Nirmalya} } @article {47603, title = {Sulfonated polyvinyl alcohol ionomer membrane favoring smooth electrodeposition of zinc for aqueous rechargeable zinc metal batteries}, journal = {Sustainable Energy \& Fuels}, volume = {5}, year = {2021}, month = {OCT}, pages = {5557-5564}, type = {Article}, abstract = {One of the failure mechanisms of aqueous rechargeable zinc metal batteries (AZMBs) involves high surface area zinc (HSAZ)/dendrite-like deposits over the Zn-metal anode during long-term cycling. Negatively charged (anionic) polymeric ionomer electrolyte membranes and separators are known for suppressing the dendrite-/HSAZ-induced failure of AZMBs. However, the preparation of cost-effective and non-fluorinated ionomers from cheap and environmentally friendly polymers is essential to leverage the feasibility of AZMBs. The current work demonstrates the potential of an ionomer electrolyte membrane (P-AS-C-Zn) made by the crystallization-induced physical cross-linking of sulfonated poly (vinyl alcohol) (PVS) and poly (vinyl alcohol) (PVA) as a dendrite-/HSAZ-inhibiting separator for AZMBs. The P-AS-C-Zn membranes exhibited excellent Zn plating/stripping behavior with a stable voltage vs. time profile beyond 1100 h, compared to their neutral PVA-C-Zn counterpart without any ionomer character (cell failure at close to 280 h). Applying the optimized P-AS-C-Zn membrane in a MnO2||Zn full cell helps retain about 50\% of the initial capacity close to 600 cycles in the absence of extra manganese salt in the electrolyte, which is indeed promising.}, issn = {2398-4902}, doi = {10.1039/d1se00865j}, author = {Vijayakumar, Vidyanand and Torris, Arun and Kurian, Maria and Mathew, Megha Mary and Ghosh, Meena and Khairnar, Ajay B. and Badiger, Manohar V. and Kurungot, Sreekumar} } @article {47311, title = {Synergistic effect of B site co-doping with Co and Ce in bifunctional oxygen electrocatalysis by oxygen deficient brownmillerite Ba2In2O5}, journal = {Catalysis Today}, volume = {375}, year = {2021}, month = {SEP}, pages = {494-500}, type = {Article}, abstract = {

Specificity in oxygen reduction and evolution reactions is pivotal in bifunctional catalysts in advanced energy devices which are expected to be active in a wide potential window and stable in both electrochemically reducing and oxidising atmospheres. State of the art noble metal catalysts for these reactions are fraught with issues whereas, metal oxides are expected to be stable in large potential window and can be tuned to have better bifunctional activity. Catalytically active metals, redox centres, oxygen vacancies etc. are some of the features of structured oxides which can be exploited in oxygen electrocatalysis. Brownmillerite family of compounds with general formula, A2B2O5\ has high concentrations of ordered oxygen vacancy in a layer and can be promising bifunctional oxygen electrocatalysts, by appropriate B site doping. Ba2In2O5\ is a well-studied system for its oxide ion conductivity and proximity of active B sites to O vacancies provide good O adsorption sites which are catalytically active. Here, cobalt and cerium are co-doped in Ba2In2O5, anticipating a synergistic effect of Ce(III)/Ce(IV) redox centre in ORR and Co activity in OER along with O vacancies providing adsorption sites. We have studied the structural changes associated with the doping by Rietveld refinement of the XRD patterns and correlated the structure to bifunctional oxygen electrocatalytic activity which is found to enhance on increasing the Co and Ce content.

}, doi = {10.1016/j.cattod.2020.05.046}, author = {Thundiyil, Shibin and Kurungot, Sreekumar and Devi, R. Nandini} } @article {47740, title = {Synergistic electronic coupling/cross-talk between the isolated metal halide units of zero dimensional heterometallic (Sb, Mn) halide hybrid with enhanced emission}, journal = {Journal of Materials Chemistry C}, volume = {10}, year = {2021}, month = {DEC }, pages = {360-370}, type = {Article}, abstract = {Heterometallic 0D metal halide hybrids, consisting of more than one kind of metal halide units, are anticipated to manifest synergistic effects on the photo-physical properties of the constituent metal halide units. Such architectures hold great promise for design and development of function-targeted materials. However, heterometallic 0D hybrids, featuring isolated metal halide units, typically do not show any synergistic effects due to large inter-unit spatial separations that inhibit interactions/coupling between the constituent metal halide units. It remains challenging to design synthetic strategies that would support structural modifications to allow synergistic electronic coupling between the metal halide units in heterometallic 0D hybrids. Here, we report synthesis and characterization of heterometallic (Sb, Mn) 0D hybrid, namely Tris SbMnCl, with isolated MnCl5 units, (Sb/Mn)Cl-6 units, dispersed in the organic ligand matrix and layer of dynamic and networked water molecules. Steady state and time resolved emission spectra (TRES) analysis suggests strong synergistic interaction between the isolated metal halide units. Efficient energy transfer from the strongly absorbing Sb centres to emissive Mn centres results in the observed enhanced emission. Proton conductivity measurements together with first-principles calculations suggest the unique role of the networked water molecules in mediating the electronic coupling/energy transfer between the separated metal halide units in Tris SbMnCl hybrid. This report highlights the role of structure/composition of the synthesized heterometallic 0D hybrid in attaining electronic dimensionality higher than 0D through synergistic electronic interaction between the isolated metal halide units.}, issn = {2050-7526}, doi = {10.1039/d1tc04704c}, author = {Biswas, Anupam and Bakthavatsalam, Rangarajan and Das, Deep K. and Sam, Jisvin and Mali, Bhupendra P. and Biswas, Chinmoy and Maana, Narugopal and Thomson, Stuart and Raavi, Sai Santosh Kumar and Kurungot, Sreekumar and Gonnade, Rajesh G. and Dutta, Sudipta and Kundu, Janardan} } @article {47055, title = {Toward pH independent oxygen reduction reaction by polydopamine derived 3D interconnected, iron carbide embedded graphitic carbon}, journal = {ACS Applied Materials \& Interfaces}, volume = {13}, year = {2021}, month = {FEB }, pages = {8147-8158}, type = {Article}, abstract = {

Recent advancements on the development of nonprecious electrocatalysts with iron (Fe) incorporated active centers have generated confidence on realizing cost-effective proton exchange membrane fuel cells (PEMFCs). However, most of these catalysts that emerged as a substitution for the platinum supported on carbon (Pt/C) catalysts in oxygen reduction reaction (ORR) are active under basic conditions, and their feasibility in PEMFCs remains as a challenge. In this scenario, this work reports the synthesis of a Pt-free oxygen reduction electrocatalyst prepared by the annealing of polydopamine grown melamine foam. The prepared catalyst has a three-dimensional (3D) interconnected bilayer network structure possessing the carbon nitride backbone wrapped by graphitic carbon layer bearing iron carbides and nitrides as the active centers (3DFePDC). Interestingly, the 3D-FePDC catalyst displayed an ORR activity both under acidic and basic conditions. Whereas the ORR performance of 3D-FePDC closely matches that of the commercial Pt/C in the basic medium, it displays only a low overpotential value of 60 mV under acidic conditions compared to its Pt counterpart. The kinetics of ORR on 3DFePDC is found to be similar to the four-electron (4e) reduction pathway displayed by Pt/C. Testing of a PEMFC in a single cell mode by using 3D-FePDC as the cathode catalyst and Nafion membrane delivered a maximum power density of 278 mW cm(-2), which is a promising value expected from a system based on the nonprecious metal cathode. Ultimately, as a cost-effective catalyst that can effectively perform irrespective of the pH conditions, 3D-FePDC offers significant prospects in the areas like fuel cells and metal-air batteries which work in acidic and/or basic conditions.

}, keywords = {acidic medium, electrocatalyst, fuel cell, graphitic carbon, Iron carbide, nitrogen doping, nonprecious metal, oxygen reduction reaction}, issn = {1944-8244}, doi = {10.1021/acsami.0c18036}, author = {Gangadharan, Pranav K. and Pandikassala, Ajmal and Kurungot, Sreekumar} } @article {47456, title = {Zinc-air batteries catalyzed using Co3O4 nanorod-supported N-doped entangled graphene for oxygen reduction reaction}, journal = {ACS Applied Energy Materials}, volume = {4}, year = {2021}, month = {MAY }, pages = {4570-4580}, type = {Article}, abstract = {

The work reported here deals with the development of an efficient non-platinum electrocatalyst for electrochemical oxygen reduction reaction (ORR) through a sequential pathway involving hydrothermal treatment followed by freeze-drying to build the desired structural architecture of the catalyst. The designed catalyst (Co3O4/nitrogen-doped entangled porous 3D graphene (NEGF)), which contains Co3O4 nanorods anchored on the surface of three-dimensional (3D)-structured N-doped graphene, was found to display higher ORR activity during single-electrode testing and demonstrate a Zn-air battery (ZAB) system. Under the hydrothermal treatment at 180 degrees C, in the presence of ammonia, nitrogen was doped into the carbon framework of graphene, which subsequently formed a self-assembled entangled 3D structure of graphene after freeze-drying. The hydrothermal treatment and freeze-drying processes were found to play vital roles in tuning the morphological and structural features of the catalyst. The doped nitrogen, apart from its favorable contribution toward ORR, helped facilitate efficient dispersion of oxide nanorods on graphene. Co3O4/NEGF displayed remarkable ORR activity in 0.1 M KOH solution, as evident from the 60 mV onset potential shift compared to the state-of-the-art Pt/C catalyst and the Tafel slope value of 74 mV dec(-1) vs 68 mV dec(-1) for Pt/C. The ZAB fabricated by employing Co3O4/NEGF as the cathode catalyst was found to be an efficient competitor for the system based on the Pt/C cathode. This high performance has been credited to the controlled interplay of the governing factors such as the interfacial interactions leading to the efficient dispersion of metal oxide nanorods, increased catalyst surface area, the cooperative effect arising from the defects present in the N-doped porous 3D graphene, and the synergetic interactions operating in the system.

}, keywords = {cobalt-oxide nanorod, freeze-drying, hydrothermal, N-doped entangled graphene, oxygen reduction reaction, zinc-air battery}, issn = {2574-0962}, doi = {10.1021/acsaem.1c00210}, author = {Manna, Narugopal and Singh, Santosh K. and Kharabe, Geeta Pandurang and Torris, Arun and Kurungot, Sreekumar} } @article {48174, title = {Air-cathode interface-engineered electrocatalyst for solid-state rechargeable zinc-air batteries}, journal = {ACS Applied Energy Materials}, volume = {5}, year = {2022}, month = {JUL }, pages = {8756-8768}, type = {Article}, abstract = {

Solid-state rechargeable zinc-air batteries (ZABs) are gaining interest as a class of portable clean energy technology due to their advantages such as high theoretical energy density, intrinsic safety, and low cost. It is expected that an appropriately triple-phase boundary (TPB) engineered, bifunctional oxygen reaction (OER and ORR) electrocatalyst at the air- electrode of ZABs can redefine the performance characteristics of these systems. To explore this possibility, an electrode material consisting of manganese- cobalt-based bimetallic spinel oxide (MnCo2O4)-supported nitrogen-doped entangled graphene (MnCo2O4/NEGF) with multiple active sites responsible for facilitating both OER and ORR has been prepared. The porous 3D graphitic support significantly affects the bifunctional oxygen reaction kinetics and helps the system display a remarkable catalytic performance. The air electrode consisting of the MnCo2O4/NEGF catalyst coated over the gas diffusion layer (GDL) ensures the effective TPB, and this feature works in favor of the rechargeable ZAB system under the charging and discharging modes. As an important structural and functional attribute of the electrocatalyst, the porosity and nitrogen doping in the 3D conducting support play a decisive aspect in controlling the surface wettability (hydrophilicity/hydrophobicity) of the air electrode. The fabricated solid-state rechargeable ZAB device with the developed electrode displayed a maximum peak power density of 202 mW cm(-2), which is significantly improved as compared to the one based on the Pt/C + RuO2 standard catalyst pair (124 mW cm(-2)). The solid-state device which displayed an initial charge-discharge voltage gap of only 0.7 V at 10 mA cm(-2) showed only a small increment of 86 mV after 50 h.

}, keywords = {air-cathode interface, bifunctional oxygen catalyst, N-doped entangled graphene, solid-state zinc-air battery, spinel oxides}, issn = {2574-0962}, doi = {10.1021/acsaem.2c01266}, author = {Manna, Narugopal and Singh, Santosh K. and Kurian, Maria and Torris, Arun and Kurungot, Sreekumar} } @article {48122, title = {Co-Ni layered double hydroxide for the electrocatalytic oxidation of organic molecules: an approach to lowering the overall cell voltage for the water splitting process}, journal = {ACS Applied Materials \& Interfaces}, volume = {14}, year = {2022}, month = {APR}, pages = {16222-16232}, type = {Article}, abstract = {

Electrocatalytic oxidation of simple organic molecules oilers a promising strategy to combat the sluggish kinetics of the water oxidation reaction (WOR). The low potential requirement, inhibition of the crossover of gases, and formation of value-added products at the anode are benefits of the electrocatalytic oxidation of organic molecules. Herein, we developed cobalt-nickel-based layered double hydroxide (LDH) as a robust material for the electrocatalytic oxidation of alcohols and urea at the anode, replacing the WOR. A facile synthesis protocol to form LDHs with different ratios of Co and Ni is adapted. It demonstrates that the reactants could be efficiently oxidized to concomitant chemical products at the anode. The half-cell study shows an onset potential of 1.30 V for benzyl alcohol oxidation reaction (BAOR), 1.36 V for glycerol oxidation reaction (GOR), 1.33 V for ethanol oxidation reaction (EOR), and 1.32 V for urea oxidation reaction (UOR) compared with 1.53 V for WOR. Notably, the hybrid electrolyzer in a full-cell configuration significantly reduces the overall cell voltage at a 20 mA cm(-2) current density by similar to 15\% while coupling with the BAOR, EOR, and GOR and similar to 12\% with the UOR as the anodic half-cell reaction. Furthermore, the efficiency of hydrogen generation remains unhampered with the types of oxidation reactions (alcohols and urea) occurring at the anode. This work demonstrates the prospects of lowering the overall cell voltage in the case of a water electrolyzer by integrating the hydrogen evolution reaction with suitable organic molecule oxidation.

}, keywords = {electrocatalytic oxidation, energy conversion, imidazole mediated, Layered compounds, water splitting}, issn = {1944-8244}, doi = {10.1021/acsami.2c00982}, author = {Shilpa, Nagaraju and Pandikassala, Ajmal and Krishnaraj, Perayil and Walko, Priyanka S. and Devi, R. Nandini and Kurungot, Sreekumar} } @article {48186, title = {Electrodeposited layered sodium vanadyl phosphate (NaxVOPO4 center dot nH(2)O) as cathode material for aqueous rechargeable zinc metal batteries}, journal = {Energy \& Fuels}, volume = {36}, year = {2022}, month = {JUN }, pages = {6520-6531}, type = {Article}, abstract = {

Aqueous rechargeable zinc metal batteries (ARZMBs) present a safer and cost-effective solution for energy storage in stationary applications. However, a major challenge is the lack of suitable cathode materials simultaneously exhibiting high operating voltage and long cycling stability. Herein, we report the polyanionic sodium-intercalated layered vanadyl phosphate [NaxVOPO4 center dot nH(2)O (NVP)] as a suitable high-voltage and stable cathode for ARZMBs. This work employs a simpler electrochemical route (electrodeposition) for the synthesis of NVP over functionalized carbon fiber substrates and its application as a binder-free cathode in ARZMBs. The electrodeposited NVP possesses a morphology of vertically aligned well-separated nanosheet bundles resembling a flower. When used as the ARZMB cathode, the NVP electrode delivers a specific discharge capacity of 100 mA h g(-1) at 0.033 A g(-1) and high cycling stability (98\% retention of the initial capacity over 1100 cycles at 0.333 A g(-1)) in a mild aqueous electrolyte with moderate zinc salt concentration. The observed electrochemical performance of NVP is credited to the synergistic effect of unique nanoflower morphology, the pillaring effect offered by the intercalated Na, and the intimate contact of the active material with the carbon fiber network. These factors are favorable for enhancing the transport of the electrolyte ions and electrons and maintaining the structural stability of the electrode during long-term cycling. The NVP electrode could also deliver appreciable performance (a discharge capacity of 73 mA h g(-) 1 and a current density of 0.033 A g(-1)) in quasi-solidstate ARZMB cells employing PVA/Zn(CF3SO3)(2) gel electrolyte.

}, issn = {0887-0624}, doi = {10.1021/acs.energyfuels.2c00831}, author = {Dilwale, Swati and Ghosh, Meena and Vijayakumar, Vidyanand and Kurungot, Sreekumar} } @article {48135, title = {Enhanced proton conductivity in amino acid based self-assembled non-porous hydrogen-bonded organic frameworks}, journal = {Chemical Communications}, volume = {58}, year = {2022}, month = {MAY}, pages = {5972-5975}, type = {Article}, abstract = {

beta-Alaninium oxalate hemihydrate, glycinium oxalate, and L-leucinium oxalate salt-cocrystals as non-porous self-assembled hydrogen-bonded organic frameworks afforded proton conductivity of 2.43 x 10(-2) S cm(-1) (60 degrees C, 95\% RH), 3.03 x 10(-2) S cm(-1) (60 degrees C, 95\% RH), and 1.19 x 10(-2) S cm(-1) (80 degrees C, 95\% RH), respectively. These materials possess an extensive 3-dimensional network of hydrogen bonds in their crystal structures, making them efficient proton conducting membranes. The reduction in conductivity values over 10(-1) S cm(-1) order upon exposure of the samples to a D2O atmosphere in extreme conditions ratified the role of humidity for the conduction of protons. This work explores the relationship between structural features and proton conductivity for the design of proton conducting membranes that are easy to synthesize, eco-friendly, and cheap with potential for futuristic applications.

}, issn = {1359-7345}, doi = {10.1039/d2cc00948j}, author = {Pramanik, Titas and Anand, Ashish and Pandikassala, Ajmal and Illathvalappil, Rajith and Kurungot, Sreekumar and Row, T. N. Guru} } @article {48356, title = {Influence of ice templating on oxygen reduction catalytic activity of metal-free heteroatom-doped mesoporous carbon derived from polypyrrole for zinc-air batteries}, journal = {Energy Technology}, volume = {10}, year = {2022}, month = {DEC}, type = {Article}, abstract = {

The development of highly active, cost-effective, and durable, noble metal-free oxygen reduction electrocatalysts is inevitable for the full-fledged implementation of fuel cells and zinc-air batteries. This work reports the synthesis of heteroatom (N, P, S)-doped metal-free mesoporous carbon-based electrocatalyst derived from polypyrrole by combining the ice templating, freeze-drying, and carbonization processes. The correlation between the structure and electrochemical activity of the polypyrrole-derived carbon-based electrocatalyst in the presence and absence of ice templating is investigated. The optimized electrocatalyst, aided by the ice-templating and freeze-drying step, shows an onset and half-wave potential (E-1/2) of 0.94 and 0.78 V vs reversible hydrogen electrode, respectively, in an alkaline electrolyte (0.1 m KOH). Later, the application of the optimized electrocatalyst is demonstrated in a primary zinc-air battery (ZAB) cell. The results prove that the ZAB device performance based on the homemade catalyst is on par with that of the state-of-the-art Pt/C cathode. The catalyst performance is correlated with the heteroatom doping and the enhanced porosity of the sample benefitted from ice templating. Ultimately, this work depicts a facile and rational synthesis of a truly metal-free electrocatalyst for the primary ZABs that can be a potential replacement for state-of-the-art systems.

}, keywords = {metal-free electrocatalysts, oxygen reduction reaction, zinc-air batteries}, issn = {2194-4288}, doi = {10.1002/ente.202200840}, author = {Kurian, Maria and Ghosh, Meena and Vijayakumar, Vidyanand and Puthiyaveetil, Priyanka Pandinhare and Torris, Arun and Kurungot, Sreekumar} } @article {48201, title = {Pseudo-boehmite AlOOH supported NGr composite-based air electrode for mechanically rechargeable Zn-air battery applications}, journal = {Journal of Materials Chemistry A}, volume = {10}, year = {2022}, month = {MAY}, pages = {10014-10025}, type = {Article}, abstract = {

Both mechanically and electrically rechargeable zinc-air batteries (ZABs) have received much interest due to their high energy density and suitability for mobile and stationary applications. However, their commercialization has been impeded by the lack of robust, low-cost and environmentally benign catalyst materials that can be easily scaled up. In this context, the present work introduces a new type of transition metal-free catalytic material (AlOOH/NGr) by anchoring the pseudo-boehmite phase of aluminium oxyhydroxide (AlOOH) nanosheets over nitrogen-doped graphene (NGr) via a single-step and straightforward hydrothermal process. Furthermore, density functional theory (DFT) based computation demonstrates that the nucleation of AlOOH starts from the N-sites and points towards the strong surface interaction between AlOOH and NGr via doped nitrogen. AlOOH/NGr consisting of thin layered pseudo-boehmite sheets uniformly distributed over NGr has displayed an oxygen reduction reaction onset potential of 0.83 V and a half-wave potential of 0.72 V, along with good catalytic durability in alkaline medium. With this, AlOOH/NGr, when used as an air electrode for fabricating a primary Zn-air battery, the system has exhibited an open circuit voltage of similar to 1.27 V with a flat discharge profile at a current rate of 10 mA cm(-2). The fabricated system delivered a specific capacity of similar to 720 mA h g(-1) and a high power density of 204 mW cm(-2) and is comparable to the counterpart system based on the state-of-the-art Pt/C (20 wt\% Pt) cathode. Additionally, the homemade battery was able to maintain its performance after 4 times of mechanical recharging of the battery, which lasted for more than 35 h at a discharge current density of 10 mA cm(-2). Thus, we have uncovered the potential of an earth-abundant metal-based catalytic system for fabricating and demonstrating a robust mechanically rechargeable zinc-air battery.

}, issn = {2050-7488}, doi = {10.1039/d2ta00546h}, author = {Kharabe, Geeta Pandurang and Manna, Narugopal and Nadeema, Ayasha and Singh, Santosh K. and Mehta, Shweta and Nair, Aathira and Joshi, Kavita and Kurungot, Sreekumar} } @article {48119, title = {Recent advances in the metal-organic framework-based electrocatalysts for trifunctional electrocatalysis}, journal = {Dalton Transactions}, volume = {51}, year = {2022}, month = {SEP}, pages = {13573-13590}, type = {Review}, abstract = {

The sustainable energy technology is in great demand due to the depletion and the risks associated with the use of fossil fuels. Various energy technologies like regenerative fuel cells, zinc-air batteries, and overall water-splitting devices have a huge scope in the growth of green energy. The efficiency of these devices is reliant upon the multifunctional electrocatalysts, which include both bifunctional and trifunctional electrocatalysts. Among the different categories of the materials used for such multifunctional electrocatalysis, metal-organic-frameworks (MOFs) occupy a very consolidated place because of their high surface area, porosity, and many other unique physicochemical properties. However, the use of MOFs for the trifunctional electrocatalytic applications is in the budding phase and needs to be explored more. Further, most of these MOF-based trifunctional electrocatalysts are derived by pyrolyzing MOFs at high temperatures. Therefore, there is a need to develop more conductive MOFs which can be directly utilized for the trifunctional applications. In this frontier article, we present the latest reports on the MOF-based materials for trifunctional applications. The material design strategies of the MOF-based materials for trifunctional electrocatalysis have been discussed. The progressive improvements made with MOFs in electrocatalytic applications have been provided with emphasis on the structural, active site and compositional requirements. Finally, the challenges and viewpoints on the future development of the MOF-based materials for trifunctional electrocatalysis have been provided.

}, issn = {1477-9226}, doi = {10.1039/d2dt01981g}, author = {Devi, Bandhana and Koner, Rik Rani and Kurungot, Sreekumar} } @article {48232, title = {Single-step synthesis of exfoliated Ti3C2Tx MXene through NaBF4/HCl etching as electrode material for asymmetric supercapacitor}, journal = {ChemistrySelect}, volume = {7}, year = {2022}, month = {MAY}, pages = {e202201166}, type = {Article}, abstract = {

Two-dimensional Ti3C2Tx MXene, derived from the parent Ti3AlC2 phase, is considered a promising electrode material for electrochemical energy storage applications. Ti3C2Tx MXene synthesis methods often employ concentrated hydrofluoric acid (HF), which is harsh, corrosive, and hazardous to the environment. Herein, we report the preparation of Ti3C2Tx MXene following a new synthetic route under a mild reaction condition comprising an aqueous solution of NaBF4 and HCl. This etching environment at a moderate temperature of 130 degrees C effectively removes the Al layer of the Ti3AlC2 precursor, assisted by the in situ formed HF in the reaction medium. Electron microscopy images of the as-prepared Ti3C2Tx (MX-130) reveal a partially exfoliated nanosheet-like morphology. The material displays a specific capacitance of 262 F g(-1) (three-electrode assembly, 1 A g(-1), -0.85 to -0.25 V vs. Hg/Hg2SO4) in 1 M H2SO4 electrolyte. The achieved specific capacitance is superior to that of Ti3C2Tx prepared via the common HF-treatment (25 F g(-1)). Additionally, the potential application of the optimized MXene as a negative electrode material is demonstrated in a quasi-solid-state RuO2|MX-130 asymmetric supercapacitor device.

}, keywords = {asymmetric supercapacitor, Electrochemistry, Fluoride salt etchant, Layered electrode materials, Transition metal carbides}, issn = {2365-6549}, doi = {10.1002/slct.202201166}, author = {Ghosh, Meena and Szunerits, Sabine and Cao, Ning and Kurungot, Sreekumar and Boukherroub, Rabah} } @article {48003, title = {Synthesis of a highly electron-deficient, water-stable, large ionic box: multielectron accumulation and proton conductivity}, journal = {Organic Letters}, volume = {24}, year = {2022}, month = {APR 19}, pages = {3038-3042}, type = {Article}, abstract = {

pi-acidic boxes exhibiting electron reservoir and proton conduction are unprecedented because of their instability in water. We present the synthesis of one of the strongest electron-deficient ionic boxes showing e(-) uptake as well as proton conductivity. Two large anions fit in the box to form anion-pi interactions and form infinite anion-solvent wires. The box with NO3-center dot center dot center dot water wires confers high proton conductivity and presents the first example that manifests redox and ionic functionality in an organic electron-deficient macrocycle.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.2c00993}, author = {Shukla, Jyoti and Illathvalappil, Rajith and Kumar, Sharvan and Chorol, Sonam and Pandikassala, Ajmal and Kurungot, Sreekumar and Mukhopadhyay, Pritam} } @article {48151, title = {Tailored synthesis of ultra-stable Au@Pd nanoflowers with enhanced catalytic properties using cellulose nanocrystals}, journal = {Carbohydrate Polymers}, volume = {292}, year = {2022}, month = {SEP}, pages = {119723}, type = {Article}, abstract = {

A green strategy for the synthesis of bimetallic core-shell Au@Pd nanoflowers (NFs) employing banana pseudostem-derived TEMPO-oxidized cellulose nanocrystals (TCNC) as both capping and shape-directing agent via seed-mediated method is presented. Flower-like nanostructures of Au@Pd bound to TEMPO-oxidized cellulose nanocrystals (TCNC-Au@Pd) were decorated on amino-functionalized graphene (NH2-RGO) without losing their unique structure, allowing them to be deployed as an efficient, reusable and a green alternative heterogeneous catalyst. The decisive role of TCNC in the structural metamorphosis of nanoparticle morphology were inferred from the structural and morphology analyses. According to our study, the presence of -OH rich TCNC appears to play a pivotal role in the structured evolution of intricate nanostructure morphology. The feasibility of the bio-supported catalyst has been investigated in two concurrently prevalent model catalytic reactions, namely the oxygen reduction reaction (ORR) and the reduction of 4-nitrophenol, the best model reactions in fuel cell and industrial catalytic applications, respectively.

}, keywords = {Au@Pd, catalysis, Cellulose nanocrystals, Nanoflowers, oxygen reduction reaction}, issn = {0144-8617}, doi = {10.1016/j.carbpol.2022.119723}, author = {Hakkeem, Hasna M. Abdul and Babu, Aswathy and Shilpa, Nagaraju and Venugopal, Adithya A. and Mohamed, A. P. and Kurungot, Sreekumar and Pillai, Saju} } @article {47826, title = {Tuning of oxygen reduction pathways through structural variation in transition metal-doped Ba2In2O5}, journal = {ChemElectroChem}, volume = {9}, year = {2022}, month = {JAN}, pages = {e202101163}, type = {Article}, abstract = {Abstract Oxygen reduction reaction (ORR) can take place either through a two-electron pathway to form H2O2 or through a four-electron pathway to form H2O. Both the reactions are important in the respective fields, viz., H2O2 production as well as fuel cell technology, and rational design of catalysts is mandatory to acquire high energy efficiency in both cases. Here, we report the structure-electrochemical property correlation of a series of perovskite related brownmillerite compounds, Ba2In0.75M0.25O5 (M=Mn/Fe/Co/Ni/Cu), synthesized by solid-state method. On transition metal doping, octahedral distortions were observed, and the highly disordered material tends to follow the 4e transfer mechanism. More symmetrical structures followed the 2e pathway to form H2O2 as the product with high peroxide selectivity. The distortion in the octahedral arrangement can be a descriptor to finetune the selectivity of the catalysts towards the 2e and 4e pathways of ORR.}, keywords = {brownmillerite, Descriptors, Electrochemical H2O2 synthesis, Octahedral distortion, oxygen reduction reaction}, doi = {10.1002/celc.202101163}, author = {Thundiyil, Shibin and Pandikassala, Ajmal and Kurungot, Sreekumar and Devi, R. Nandini} } @article {48200, title = {Unravelling faradaic electrochemical efficiencies over Fe/Co spinel metal oxides using surface spectroscopy and microscopy techniques}, journal = {Nanoscale}, volume = {14}, year = {2022}, month = {NOV }, pages = {15928-15941}, type = {Article}, abstract = {

Cobalt and iron metal-based oxide catalysts play a significant role in energy devices. To unravel some interesting parameters, we have synthesized metal oxides of cobalt and iron (i.e. Fe2O3, Co3O4, Co2FeO4 and CoFe2O4), and measured the effect of the valence band structure, morphology, size and defects in the nanoparticles towards the electrocatalytic hydrogen evolution reaction (HER), the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). The compositional variations in the cobalt and iron precursors significantly alter the particle size from 60 to \<10 nm and simultaneously the shape of the particles (cubic and spherical). The Tauc plot obtained from the solution phase ultraviolet (UV) spectra of the nanoparticles showed band gaps of 2.2, 2.3, 2.5 and 2.8 eV for Fe2O3, Co3O4, Co2FeO4 and CoFe2O4, respectively. Further, the valence band structure and work function analysis using ultraviolet photoelectron spectroscopy (UPS) and core level X-ray photoelectron spectroscopy (XPS) analyses provided better structural insight into metal oxide catalysts. In the Co3O4 system, the valence band structure favors the HER and Fe2O3 favors the OER. The composites Co2FeO4 and CoFe2O4 show a significant change in their core level (O 1s, Co 2p and Fe 2p spectra) and valence band structure. Co3O4 shows an overpotential of 370 mV against 416 mV for Fe2O3 at a current density of 2 mA cm(-2) for the HER. Similarly, Fe2O3 shows an overpotential of 410 mV against the 435 mV for Co3O4 at a current density of 10 mA cm(-2) for the OER. However, for the ORR, Co3O4 shows 70 mV improvement in the half-wave potential against Fe2O3. The composites (Co2FeO4 and CoFe2O4) display better performance compared to their respective parent oxide systems (i.e., Co3O4 and Fe2O3, respectively) in terms of the ORR half-wave potential, which can be attributed to the presence of the oxygen vacancies over the surface in these systems. This was further corroborated in density functional theory (DFT) simulations, wherein the oxygen vacancy formation on the surface of CoFe2O4(001) was calculated to be significantly lower (similar to 50 kJ mol(-1)) compared to Co3O4 (001). The band diagram of the nanoparticles constructed from the various spectroscopic measurements with work function and band gap provides in-depth understanding of the electrocatalytic process.

}, issn = {2040-3364}, doi = {10.1039/d2nr04170g}, author = {Kashyap, Varchaswal and Pandikassala, Ajmal and Singla, Gourav and Khan, Tuhin Suvra and Haider, M. Ali and Vinod, C. P. and Kurungot, Sreekumar} } @article {48335, title = {2D layered nanomaterials as fillers in polymer composite electrolytes for lithium batteries}, journal = {Advanced Energy Materials}, volume = {13}, year = {2023}, month = {APR}, type = {Review}, abstract = {

Polymer composite electrolytes (PCEs), i.e., materials combining the disciplines of polymer chemistry, inorganic chemistry, and electrochemistry, have received tremendous attention within academia and industry for lithium-based battery applications. While PCEs often comprise 3D micro- or nanoparticles, this review thoroughly summarizes the prospects of 2D layered inorganic, organic, and hybrid nanomaterials as active (ion conductive) or passive (nonion conductive) fillers in PCEs. The synthetic inorganic nanofillers covered here include graphene oxide, boron nitride, transition metal chalcogenides, phosphorene, and MXenes. Furthermore, the use of naturally occurring 2D layered clay minerals, such as layered double hydroxides and silicates, in PCEs is also thoroughly detailed considering their impact on battery cell performance. Despite the dominance of 2D layered inorganic materials, their organic and hybrid counterparts, such as 2D covalent organic frameworks and 2D metal-organic frameworks are also identified as tuneable nanofillers for use in PCE. Hence, this review gives an overview of the plethora of options available for the selective development of both the 2D layered nanofillers and resulting PCEs, which can revolutionize the field of polymer-based solid-state electrolytes and their implementation in lithium and post-lithium batteries.

}, keywords = {2D materials, clay minerals, covalent organic frameworks, metal-organic frameworks, MXene, polymer composite electrolyte, solid-state batteries}, issn = {1614-6832}, doi = {10.1002/aenm.202203326}, author = {Vijayakumar, Vidyanand and Ghosh, Meena and Asokan, Kiran and Sukumaran, Santhosh Babu and Kurungot, Sreekumar and Mindemark, Jonas and Brandell, Daniel and Winter, Martin and Nair, Jijeesh Ravi} } @article {48935, title = {Active site engineering and theoretical aspects of {\textquoteleft}{\textquoteleft}Superhydrophilic{\textquoteright}{\textquoteright} nanostructure array enabling efficient overall water electrolysis}, journal = {Small}, volume = {19}, year = {2023}, month = {DEC}, type = {Article}, abstract = {

The rational design of noble metal-free electrocatalysts holds great promise for cost-effective green hydrogen generation through water electrolysis. In this context, here, the development of a superhydrophilic bifunctional electrocatalyst that facilitates both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline conditions is demonstrated. This is achieved through the in situ growth of hierarchical NiMoO4@CoMoO4 center dot xH(2)O nanostructure on nickel foam (NF) via a two-step hydrothermal synthesis method. NiMoO4@CoMoO4 center dot xH(2)O/NF facilitates OER and HER at the overpotentials of 180 and 220 mV, respectively, at the current density of 10 mA cm(-2). The NiMoO4@CoMoO4 center dot xH(2)O/NF parallel to NiMoO4@CoMoO4 center dot xH(2)O/NF cell can be operated at a potential of 1.60 V compared to 1.63 V displayed by the system based on the Pt/C@NF parallel to RuO2@NF standard electrode pair configuration at 10 mA cm(-2) for overall water splitting. The density functional theory calculations for the OER process elucidate that the lowest Delta G of NiMoO4@CoMoO4 compared to both Ni and NiMoO4 is due to the presence of Co in the OER catalytic site and its synergistic interaction with NiMoO4. The preparative strategy and mechanistic understanding make the windows open for the large-scale production of the robust and less expensive electrode material for the overall water electrolysis.

}, keywords = {density functional theory (DFT) study, hydrogen evolution reaction (HER), Hydrothermal synthesis, oxygen evolution reaction (OER), superhydrophilic nanostructures, synergistic interaction, water electrolysis}, issn = {1613-6810}, doi = {10.1002/smll.202304143}, author = {Barik, Sidharth and Kharabe, Geeta Pandurang and Illathvalappil, Rajith and Singh, Chandrodai Pratap and Kanheerampockil, Fayis and Walko, Priyanka S. and Bhat, Suresh K. and Devi, R. Nandini and Vinod, C. P. and Krishnamurty, Sailaja and Kurungot, Sreekumar} } @article {48692, title = {Binder-free and flexible VOPO4/CNT film as cathode for aqueous rechargeable Zn-metal battery}, journal = {Advanced Sustainable Systems}, volume = {7}, year = {2023}, month = {SEP}, type = {Article}, abstract = {

Aqueous rechargeable Zn-metal batteries (AZMBs) are promising energy storage aids due to their inherent safety, low cost, and competent performance, with prospects in stationary and portable applications. In this regard, one of the critical requirements is developing electrodes that can adapt to mechanical deformation without compromising the charge storage performance. The current work demonstrates the development of a binder-free and mechanically flexible composite cathode film (VP/fCNT-F, where {\textquoteleft}F{\textquoteright} stands for the film) based on VOPO4 (VP) and functionalized carbon nanotubes (fCNTs). The VP/fCNT-F film processing involves simple vacuum filtration of the composite obtained from the in-situ reaction of the fCNTs and the VP precursor in an aqueous medium. The functionalization of carbon nanotube (CNT) is important for the homogenous dispersion of VP and fCNT. The VP/fCNT-F electrode is used as a monolithic electrode in AZMB cells in combination with both liquid and quasi-solid-state gel polymer electrolytes. Besides, the utility of the VP/fCNT-F electrode in a flexible battery configuration is also demonstrated. Interestingly, in both the coin-cell and flexible configurations, the VP/fCNT-F electrode delivers a comparable discharge capacity of 90 and 78 mAh g(-1), respectively (at 0.1 A g(-1)), validating the advantage of the binder-free VP/fCNT-F electrode for AZMBs.

}, keywords = {binder-free cathodes, flexible batteries, layered VOPO4, polymer gel electrolytes, self-standing flexible films}, issn = {2366-7486}, doi = {10.1002/adsu.202300141}, author = {Dilwale, Swati and Babu, Athira and Puthiyaveetil, Priyanka Pandinhare and Kurian, Maria and Ghosh, Meena and Kurungot, Sreekumar} } @article {49004, title = {Chemically gradient hydrogen-bonded organic framework crystal film}, journal = {Angewandte Chemie-International Edition}, volume = {62}, year = {2023}, month = {JUL }, type = {Article}, abstract = {

Hydrogen-bonded organic frameworks (HOFs) are ordered supramolecular solid structures, however, nothing much explored as centimetre-scale self-standing films. The fabrication of such crystals comprising self-supported films is challenging due to the limited flexibility and interaction of the crystals, and therefore studies on two-dimensional macrostructures of HOFs are limited to external supports. Herein, we introduce a novel chemical gradient strategy to fabricate a crystal-deposited HOF film on an in situ-formed covalent organic polymer film (Tam-Bdca-CGHOF). The fabricated film showed versatility in chemical bonding along its thickness from covalent to hydrogen-bonded network. The kinetic-controlled Tam-Bdca-CGHOF showed enhanced proton conductivity (8.3x10(-5) S cm(-1)) compared to its rapid kinetic analogue, Tam-Bdca-COP (2.1x10(-5) S cm(-1)), which signifies the advantage of bonding-engineering in the same system.

}, keywords = {Chemical Gradience, Crystal Films, Free-Standing Films, hydrogen-bonded organic framework, Interfacial Chemistry, proton conductivity}, issn = {1433-7851}, doi = {10.1002/anie.202304313}, author = {Mohammed, Abdul Khayum and Raya, Jesus and Pandikassala, Ajmal and Addicoat, Matthew A. and Gaber, Safa and Aslam, Mohamed and Ali, Liaqat and Kurungot, Sreekumar and Shetty, Dinesh} } @article {48309, title = {Cobalt-manganese modified theophrastite phase of nickel hydroxide nanoflower arrays on nickel foam as a self-standing bifunctional electrode for overall water electrolysis}, journal = {Sustainable Energy \& Fuels}, volume = {7}, year = {2023}, month = {MAY}, pages = {2428-2440}, type = {Article}, abstract = {

Designing and developing self-supported electrodes for water electrolysis is attractive as compared to conventional catalyst-coated electrodes. Herein, a (Co0.3Mn0.1Ni0.6)(OH)(2)/NF nanocomposite is prepared by anchoring (Co0.3Mn0.1Ni0.6)(OH)(2)via simple one-pot hydrothermal synthesis on nickel foam. The presence of Mn induces the external electronic structure of Co(OH)(2), and this also improves the electrochemically active surface area (ECSA). These favor better accessibility of active sites and increased intrinsic activity for the OER and HER. (Co0.3Mn0.1Ni0.6)(OH)(2)/NF has shown promising electrochemical activity toward the OER and HER in a 1 M KOH electrolyte, with an overpotential of 270 mV for the OER and 163 mV for the HER to deliver 10 mA cm(-2) current density. The overall water splitting was performed by employing (Co0.3Mn0.1Ni0.6)(OH)(2)/NF as both the cathode and anode by displaying a voltage of 1.62 V at 10 mA cm(-2), which is comparable to that extracted from a similar system based on the state-of-the-art Pt/C@NF cathode and RuO2@NF anode (1.60 V at 10 mA cm(-2)) standard electrode pair. Interestingly, at high current densities, the (Co0.3Mn0.1Ni0.6)(OH)(2)/NF//(Co0.3Mn0.1Ni0.6)(OH)(2)/NF system displayed better overall water splitting performance (1.78 V at 100 mA cm(-2)) compared to its Pt/C@NF//RuO2@NF (1.89 V at 100 mA cm(-2)) counterpart while displaying a stable output during the evolution period that lasted for 24 h. The amounts of H-2 and O-2 produced are estimated to be 701.2 and 358.6 mmol, respectively, at a time interval of 1 h; these amounts correspond to an similar to 1 : 2 ratio of O-2 and H-2, respectively. This study confirms the capability for employing (Co0.3Mn0.1Ni0.6)(OH)(2)/NF as a bi-functional and self-standing electrode for the realistic demonstrations of overall water splitting applications.

}, issn = {2398-4902}, doi = {10.1039/d3se00233k}, author = {Kharabe, Geeta Pandurang and Illathvalappil, Rajith and Barik, Sidharth and Kanheerampockil, Fayis and Walko, Priyanka S. and Bhat, Suresh K. and Devi, R. Nandini and Kurungot, Sreekumar} } @article {48676, title = {Electrode|electrolyte interface enhancement in quasi-solid-state zinc-air batteries through an anion conducting polymer electrolyte interlayer by in situ polymerization}, journal = {Journal of Materials Chemistry A}, volume = {11}, year = {2023}, month = {JUL}, pages = {14776-14787}, type = {Article}, abstract = {

This work introduces a novel concept of electrode|electrolyte interface enhancement using an ultraviolet (UV) light-assisted in situ polymerization strategy to improve the performance of quasi-solid-state zinc-air batteries (ZABs). The suitability of the UV polymerization strategy to process a mechanically stable OH- conducting anion exchange polymer electrolyte membrane (AEPEM) reinforced by a glass fiber (GF) separator is also reported. The in situ polymerized ionomer-skin/interlayer (a thin anion-conducting polymer coating over the air-cathode of ZAB) acts as a buffer layer to narrow down the performance gap generally observed between ZABs possessing quasi-solid-state electrolytes and standard liquid electrolytes, respectively. For instance, when combined with the in situ polymerization strategy, a rechargeable ZAB (rZAB) based on an AEPEM-GF composite membrane delivered a high power density of 140 mW cm(-2), higher than that of the one without an in situ polymerized ionomer interlayer (120 mW cm(-2)). Notably, in a flexible rZAB configuration, this new strategy resulted in enhanced rate capability and cycling stability for 14 h at an operating current density of 2 mA cm(-2).

}, issn = {2050-7488}, doi = {10.1039/d3ta02320f}, author = {Kurian, Maria and Vijayakumar, Vidyanand and Manna, Narugopal and Kanheerampockil, Fayis and Bhat, Suresh and Kurungot, Sreekumar} } @article {48493, title = {Microporous 3D-structured hierarchically entangled graphene-supported Pt3Co alloy catalyst for PEMFC application with process-friendly features}, journal = {ACS Applied Materials \& Interfaces}, volume = {15}, year = {2023}, month = {JUN }, pages = {28023-28035}, type = {Article}, abstract = {

To improve the oxygen reduction reaction(ORR) performance in aproton-exchange membrane fuel cell (PEMFC) cathode with respect tomass activity and durability, a suitable electrocatalyst design strategyis essentially needed. Here, we have prepared a sub-three nm-sizedplatinum (Pt)-cobalt (Co) alloy (Pt3Co)-supportedN-doped microporous 3D graphene (Pt3Co/pNEGF) by usingthe polyol synthesis method. A microwave-assisted synthesis methodwas employed to prepare the catalyst based on the 3D porous carbonsupport with a large pore volume and dense micro-/mesoporous surfaces.The ORR performance of Pt3Co/pNEGF closely matches withthe state-of-the-art commercial Pt/C catalyst in0.1 M HClO4, with a small overpotential of 10 mV. The 3Dmicroporous structure of the N-doped graphene significantly improvesthe mass transport of the reactant and thus the overall ORR performance.As a result of the lower loading of Pt in Pt3Co/pNEGF ascompared to that in Pt/C, the alloy catalyst achieved 1.5 times highermass activity than Pt/C. After 10,000 cycles, the difference in theelectrochemically active surface area (ECSA) and half-wave potential(E (1/2)) of Pt3Co/pNEGF is foundto be 5 m(2) g(Pt) (-1) (Delta ECSA)and 24 mV (Delta E (1/2)), whereas, forPt/C, these values are 9 m(2) g(Pt) (-1) and 32 mV, respectively. Finally, in a realistic perspective, single-celltesting of a membrane electrode assembly (MEA) was made by sandwichingthe Pt3Co/pNEGF-coated gas diffusion layers as the cathodedisplayed a maximum power density of 800 mW cm(-2) under H-2-O-2 feed conditions with aclear indication of helping the system in the mass-transfer region(i.e., the high current dragging condition). The nature of the I-V polarization shows a progressivelylower slope in this region of the polarization plot compared to asimilar system made from its Pt/C counterpart and a significantlyimproved performance throughout the polarization region in the caseof the system made from the Pt3Co/NEGF catalyst (withoutthe microwave treatment) counterpart. These results validate the betterprocess friendliness of Pt3Co/pNEGF as a PEMFC electrode-specificcatalyst owing to its unique texture with 3D architecture and well-definedporosity with better structural endurance.

}, keywords = {microwave synthesis, N-doped porous 3D graphene, ORR, PEMFC, polyol synthesis, Pt3Co alloy}, issn = {1944-8244}, doi = {10.1021/acsami.3c03372}, author = {Manna, Narugopal and Singh, Mayank and Kurungot, Sreekumar} } @article {48324, title = {Pt-anchored-zirconium phosphate nanoplates as high-durable carbon-free oxygen reduction reaction electrocatalyst for PEM fuel cell applications}, journal = {Advanced Sustainable Systems}, volume = {7}, year = {2023}, month = {FEB}, type = {Article}, abstract = {

Commercially available platinum-supported carbon (Pt/C) catalysts are the most widely used oxygen reduction reaction (ORR) electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs). However, inadequate active triple-phase boundary formation and carbon oxidation in Pt/C during PEMFC operation shorten its lifetime and efficiency. In this direction, a new class of carbon-free electrocatalysts for ORR is prepared by dispersing Pt nanoparticles on ZrP (Zirconium phosphates) nanoplates. In one case (ZrP@Pt), the Pt nanoparticles are found to be closely distributed and completely covering the ZrP nanoplates, whereas in the second case (Pt/ZrP), the Pt nanoparticles selectively restrict dispersion along the edges of the support. ZrP as the support displays an intrinsic proton conductivity of approximate to 0.5 x 10(-4) S cm(-1) at 70 degrees C, with an activation energy (E-a) of 0.19 eV. Pt/ZrP shows better durability after 3000 start-stop cycles. The mass activity of Pt/ZrP is increased by 4.6 times compared to Pt/C, which exhibits a loss in mass activity by 1.37 times. The single-cell level validation of ZrP@Pt, Pt/ZrP, and Pt/C as the electrocatalysts in PEMFC at an operating potential of 0.60 V shows the achievable current densities of 0.600, 0.890, and 0.890 A cm(-2).

}, keywords = {carbon-free electrocatalysts, fuel cells, oxygen reduction reaction, zirconium phosphate}, issn = {2366-7486}, doi = {10.1002/adsu.202200330}, author = {Kumar, Sachin and Yoyakki, Athira and Pandikassala, Ajmal and Soni, Roby and Kurungot, Sreekumar} } @article {48333, title = {Salicylaldehydate coordinated two-dimensional-conjugated metal-organic frameworks}, journal = {Chemical Communications}, volume = {59}, year = {2023}, month = {FEB }, pages = {2608-2611}, type = {Article}, abstract = {

A novel class of copper-based 2D-c-MOF was synthesized from 1,3,5-triformylphloroglucinol using green mechano-chemistry. Herein, metal coordination with the salicylaldehyde functional moiety was explored for the first time in MOFs. Moreover, an intrinsic semiconductive copper-based SA-MOF thin film was fabricated using an in situ salt-free method at room temperature.

}, issn = {1359-7345}, doi = {10.1039/d2cc06283f}, author = {Mohammed, Abdul Khayum and Pena-Sanchez, Pilar and Pandikassala, Ajmal and Gaber, Safa and AlKhoori, Ayesha A. and Skorjanc, Tina and Polychronopoulou, Kyriaki and Kurungot, Sreekumar and Gandara, Felipe and Shetty, Dinesh} } @article {48798, title = {Unlocking the potential of proton conductivity in guanidinium-based ionic covalent organic nanosheets (iCONs) through pore interior functionalization}, journal = {Applied Materials Today}, volume = {33}, year = {2023}, month = {AUG}, pages = {101866}, type = {Article}, abstract = {

Recently, scientists have been exploring the incorporation of proton carriers such as water and phosphoric acid (PA) into the pores and channels of porous materials to enhance proton conduction performance. Ionic covalent organic nanosheets (iCONs) have been identified as promising functional materials due to their inbuilt ionic interfaces, which can facilitate strong interaction with counter ions present inside the pore structure and thus shorten ion transport pathways. However, there is a lack of research related to proton conductivity in iCONs loaded with PA. To address this, we prepared three functionalized guanidinium-based iCONs using a solvothermal condensation reaction between guanidinium amine (TG) and functionalized terephthaldehyde (Da, Dha, and Dma). PA was also incorporated into the iCON structure via ex situ loading to observe its effects on proton conduction performance. The results showed that both the iCONs and PA-iCONs were highly stable in water, organic solvents, acidic and basic media. Amongst these PA-iCONs, one with hydroxyl-functionalization (PA-DhaTG) displayed high proton conductivity at 90 degrees C and 95\% relative humidity due to a Grotthuss mechanism for protons. These functionalized guanidinium-based iCONs could prove useful for applications in energy conversion devices.

}, keywords = {chemical stability, Functionalized pore interior, Guanidinium group, ionic covalent organic nanosheets, proton conductivity}, issn = {2352-9407}, doi = {10.1016/j.apmt.2023.101866}, author = {Kumar, Sushil and Hu, Jiahui and Pandikassala, Ajmal and Kurungot, Sreekumar and Addicoat, Matthew A. and Szekely, Gyorgy} } @article {49324, title = {Advanced 3D network of N-doped graphitic carbon with FeNi alloy embedding for high-performance rechargeable Zn-air batteries}, journal = {Advanced Sustainable Systems}, volume = {8}, year = {2024}, month = {JUL}, type = {Article}, abstract = {

Despite the significant progress in Zn-air batteries (ZABs), their widespread use in the rechargeable sector is hindered due to the scarcity of efficient bifunctional oxygen catalysts that can catalyze both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). To address this, an ORR/OER bifunctional electrocatalyst is designed with ultrafine alloyed FeNi nanoparticles encapsulated in a 3D interconnected N- doped carbon network structure, featuring a carbon nitride backbone enclosed in graphitic carbon. The FeNi electrocatalyst (3DFeNiPDC) showed good bifunctional activity toward both ORR and OER in the basic medium with a low overpotential value of 30 mV for ORR and 6 mV for OER compared to its state-of-the-art counterparts Pt/C, and RuO2, respectively. Utilizing 3DFeNiPDC in a rechargeable Zn-air battery (RZAB) yields an open circuit voltage (OCV) of 1.35 V, a maximum power density of 232 mW cm-2, and an energy density of 707 W h kg-1. Additionally, a flexible RZAB employing 3DFeNiPDC demonstrates an OCV of 1.4 V with various bending angles. These finding suggest 3DFeNiPDC as a viable alternative to noble metal-based RZABs, offering superior bifunctional electrocatalytic activity and stability, particularly with its enhanced air-breathing properties facilitating improved operability under practical conditions. The bifunctional electrocatalytic activity of FeNi alloy nanoparticles embedded in a 3D- interconnected N-doped graphitic carbon (3DFeNiPDC) for both oxygen reduction and oxygen evolution is studied. The 3D architecture and core-shell characteristics of FeNi alloy nanoparticles provide better activity and stability for oxygen electrocatalysis. The electrocatalytic activity of 3DFeNiPDC has been exploited for liquid-state and solid-state flexible rechargeable zinc-air batteries. image

}, keywords = {Oxygen Evolution Reaction, oxygen reduction reaction, rechargeable flexible zinc-air battery}, issn = {2366-7486}, doi = {10.1002/adsu.202400012}, author = {Pandikassala, Ajmal and Kurian, Maria and Gangadharan, Pranav K. and Torris, Arun and Kurungot, Sreekumar} } @article {49367, title = {Aluminium, nitrogen-dual-doped reduced graphene oxide Co-existing with cobalt-encapsulated graphitic carbon nanotube as an activity modulated electrocatalyst for oxygen electrocatalyst for oxygen electrochemistry applications}, journal = {Small}, volume = {20}, year = {2024}, month = {AUG}, type = {Article}, abstract = {

There is a rising need to create high-performing, affordable electrocatalysts in the new field of oxygen electrochemistry. Here, a cost-effective, activity-modulated electrocatalyst with the capacity to trigger both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in an alkaline environment is presented. The catalyst (Al, Co/N-rGCNT) is made up of aluminium, nitrogen-dual-doped reduced graphene oxide sheets co-existing with cobalt-encapsulated carbon nanotube units. Based on X-ray Absorption Spectroscopy (XAS) studies, it is established that the superior reaction kinetics in Al, Co/N-rGCNT over their bulk counterparts can be attributed to their electronic regulation. The Al, Co/N-rGCNT performs as a versatile bifunctional electrocatalyst for zinc-air battery (ZAB), delivering an open circuit potential approximate to 1.35 V and peak power density of 106.3 mW cm-2, which are comparable to the system based on Pt/C. The Al, Co/N-rGCNT-based system showed a specific capacity of 737 mAh gZn-1 compared to 696 mAh gZn-1 delivered by the system based on Pt/C. The DFT calculations indicate that the adsorption of Co in the presence of Al doping in NGr improves the electronic properties favoring ORR. Thus, the Al, Co/N-rGCNT-based rechargeable ZAB (RZAB) emerges as a highly viable and affordable option for the development of RZAB for practical applications. This manuscript reports the development of a new bifunctional catalyst that exhibits high activity and stability under practical operating conditions. The catalyst (Al, Co/N-rGCNT) is made up of aluminium, nitrogen-dual-doped reduced graphene oxide sheets co-existing with the in situ formed cobalt-encapsulated CNT units is synthesized by a scalable pyrolysis method in an inert Ar atmosphere. The developed electrocatalyst achieved enhanced the oxygen reduction reaction (ORR) and the oxygen evolution reaction OER activity as a result of the favorable synergistic modulations and the system can serve as a process-friendly air-electrode for rechargeable zinc-air battery (RZAB). image

}, keywords = {Al, Bifunctional catalyst, DFT study, encapsulated structure, N-dual doping, Oxygen Evolution Reaction, oxygen reduction reaction, rechargeable zinc-air battery, X-ray absorption spectroscopy}, issn = {1613-6810}, doi = {10.1002/smll.202400012}, author = {Kharabe, Geeta Pandurang and Barik, Sidharth and Veeranmaril, Sudheesh Kumar and Nair, Aathira and Illathvalappil, Rajith and Yoyakki, Athira and Joshi, Kavita and Vinod, Chathakudath Prabhakaran and Kurungot, Sreekumar} } @article {49360, title = {Breaking the Pt electron symmetry and OH spillover towards ptir active center for performance modulation in direct ammonia fuel cell}, journal = {Small}, volume = {20}, year = {2024}, month = {DEC}, type = {Article}, abstract = {

The growing interest in low-temperature direct ammonia fuel cells (DAFCs) arises from the utilization of a carbon-neutral ammonia source; however, DAFCs encounter significant electrode overpotentials due to the substantial energy barrier of the *NH2 to *NH dehydrogenation, compounded by the facile deactivation by *N on the Pt surface. In this work, a unique catalyst, Pt4Ir@AlOOH/NGr i.e., Pt4Ir/ANGr, is introduced composed of PtIr alloy nanoparticles controllably decorated on the pseudo-boehmite phase of AlOOH-supported nitrogen-doped reduced graphene (AlOOH/NGr) composite, synthesized via the polyol reduction method. The detailed studies on the structural and electronic properties of the catalyst by XAS and VB-XPS reveal the possible electronic modulations. The optimized Pt4Ir/ANGr composition exhibits a significantly improved onset potential and mass activity for AOR. The DFT study confirms the OHad species spillover by AlOOH and Pt4Ir (100) facilitates the conversion of the *NH2 to *NH with minimal energy barriers. Finally, testing of DAFC at the system level using a membrane electrode assembly (MEA) with Pt4Ir/ANGr as the anode catalyst, demonstrating the suitability of the catalyst for its practical applications. This study thus uncovers the potential of the Pt4Ir catalyst in synergy with ANGr, largely addressing the challenges in hydrogen transportation, storage, and safety within DAFCs. In this article, a versatile catalyst, Pt4Ir/ANGr, is introduced composed of PtIr alloy nanoparticles decorated on AlOOH/NGr composite. The AlOOH provides an -OH-rich surface conducive to the facile adsorption and decoration of the PtIr alloy nanoparticles and OHad species spillover from AlOOH to the Pt4Ir active center during AOR, further validating the higher experimental activity obtained in Pt4Ir/ANGr. image

}, keywords = {ammonia oxidation reaction (AOR), d-band center, density functional theory (DFT) study, direct ammonia fuel cells, hydroxyl spillover effect, XAS analysis}, issn = {1613-6810}, doi = {10.1002/smll.202406589}, author = {Barik, Sidharth and Kharabe, Geeta Pandurang and Samal, Pragnya Paramita and Urkude, Rajashri R. and Kumar, Sachin and Yoyakki, Athira and Vinod, C. P. and Krishnamurty, Sailaja and Kurungot, Sreekumar} } @article {49651, title = {Cathode|electrolyte interface engineering by a hydrogel polymer electrolyte for a 3D porous high-voltage cathode material in a quasi-solid-state zinc metal battery by in situ polymerization}, journal = {SMALL}, volume = {20}, year = {2024}, month = {OCT}, pages = {2403158}, type = {Article}, abstract = {

This work highlights the development of a superior cathode|electrolyte interface for the quasi solid-state rechargeable zinc metal battery (QSS-RZMB) by a novel hydrogel polymer electrolyte using an ultraviolet (UV) light-assisted in situ polymerization strategy. By integrating the cathode with a thin layer of the hydrogel polymer electrolyte, this technique produces an integrated interface that ensures quick Zn2+ ion conduction. The coexistence of nanowires for direct electron routes and the enhanced electrolyte ion infiltration and diffusion by the 3D porous flower structure with a wide open surface of the Zn-MnO electrode complements the interface formation during the in situ polymerization process. The QSS-RZMB configured with an integrated cathode (i-Zn-MnO) and the hydrogel polymer electrolyte (PHPZ-30) as the separator yields a comparable specific energy density of 214.14 Wh kg(-1) with that of its liquid counterpart (240.38 Wh kg(-1), 0.5 M Zn(CF3SO3)(2) aqueous electrolyte). Other noteworthy features of the presented QSS-RZMB system include its superior cycle life of over 1000 charge-discharge cycles and 85\% capacity retention with 99\% coulombic efficiency at the current density of 1.0 A g(-1), compared to only 60\% capacity retention over 500 charge-discharge cycles displayed by the liquid-state system under the same operating conditions.

}, keywords = {cathode-electrolyte interface tuning, dendrite inhibition, epitaxial zinc deposition, hydrogel polymer electrolyte, In situ polymerization, Quasi solidstate rechargeable zinc metal battery}, issn = {1613-6810}, doi = {10.1002/smll.202403158}, author = {Puthiyaveetil, Priyanka Pandinhare and Torris, Arun and Dilwale, Swati and Kanheerampockil, Fayis and Kurungot, Sreekumar} } @article {49067, title = {Co-incorporated N-doped micro-meso porous carbon as an electrocatalyst for oxygen reduction reaction and Zn-air battery}, journal = {Energy and Fuels}, volume = {38}, year = {2024}, month = {APR }, pages = {7196-7207}, type = {Article}, abstract = {

Metal-organic frameworks are considered ideal precursors for the preparation of transition-metal, heteroatom-doped carbon catalysts that are perceived to be efficient electrocatalysts for energy storage devices. Herein, we demonstrate the synthesis of ZIF-67-derived Co-incorporated N-doped porous carbon catalysts supported on high surface area microporous carbon prepared from a lotus seed shell. The combination of the two carbon catalysts in different weight ratios resulted in Co-incorporated N-doped carbon sheets with tuned surface area and porosity, enabling enhanced oxygen reduction reaction (ORR) activity in an alkaline medium. The optimized carbon catalyst ZL 600 (3:1) exhibited a half-wave potential of 0.79 V vs RHE and a limiting current density of -4.38 mA cm(-2) in 0.1 M KOH solution with higher stability and methanol tolerance. The optimized sample ZL 600 (3:1) demonstrated as a cathode in a zinc-air battery exhibited an open circuit voltage of 1.29 V with a flat discharge profile at a current rate of 10 mA cm(-2). The homemade system produced a specific capacity of 610 mAh g(-1) and a peak power density of 111 mW cm(-2), comparable to the cathode made with Pt/C. The high micro-mesoporosity, pyridinic and pyrrolic nitrogen contents, as well as enriched Co-active centers protected by carbon sheets favorably contributed to the efficient ORR mechanism.

}, issn = {0887-0624}, doi = {10.1021/acs.energyfuels.4c00059}, author = {Priya, Vaishna K. and Kharabe, Geeta Pandurang and Barik, Sidharth and Mohamed, A. Peer and Kurungot, Sreekumar and Hareesh, Unnikrishnan Nair Saraswathy} } @article {48907, title = {Conductive metal-organic frameworks for zinc-air battery application: design principles, recent trends and prospects}, journal = {Journal of Materials Chemistry A}, volume = {12}, year = {2024}, month = {JAN }, pages = {2605-2619}, type = {Journal Article }, abstract = {

Electrochemical energy conversion and storage systems have an indispensable place in the modern world to fulfill the increasing energy demands. Among the different storage devices, rechargeable zinc-air batteries (ZABs) have become one of the most promising energy technologies owing to the abundance and inexpensiveness of Zn, simple operation, environmental friendliness, and reasonable energy density. However, the sluggishness of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occurring in ZABs is a serious obstacle in their progress and commercialization. This creates a need for the development of efficient bifunctional electrocatalysts for ORR and OER. Conductive metal-organic frameworks (cMOFs) imbibing the general properties of MOFs, like high surface area, tunable porosity, redox-active centers, and additional intrinsic conductivity, can be a very lucrative option for developing bifunctional ORR and OER electrocatalysts for ZAB applications. In this review, we discuss the conductivity and design strategies of conductive MOFs, the basic configuration of ZABs, and the use of cMOFs for ZAB applications. The future directions for the improvement of cMOFs for ZABs have been provided, which hopefully will incite interest among researchers for further exploring cMOFs for ZABs. Electrochemical energy conversion and storage systems have an indispensable place in the modern world to fulfill the increasing energy demands.

}, keywords = {Biofunctional Oxygen Electrocatalyst, Electrical conductivity, Energy storage, Fuel-Cells, li-ion batteries}, issn = {2050-7488}, doi = {10.1039/d3ta03753c}, author = {Devi, Bandhana and Kurungot, Sreekumar} } @article {49308, title = {F-doped nickel cobalt oxide-carbon composite electrocatalysts paired with mechanically robust anion-conducting chitosan membranes for flexible and rechargeable zinc-air batteries}, journal = {ACS Applied Energy Materials}, volume = {7}, year = {2024}, month = {AUG}, pages = {7037-7054}, type = {Article}, abstract = {

High-performing, cost-effective electrocatalysts and anion-conducting polymer electrolyte membranes are essential for realizing commercially affordable zinc-air batteries (ZABs). In this context, the present work deals with the development of a bifunctional electrocatalyst and an anion-exchange quasi-solid-state electrolyte membrane (based on quaternary ammonium group-grafted chitosan) for demonstrating flexible and rechargeable ZABs. The electrocatalyst composed of NiCoO2 nanoparticles supported on a carbon framework showcased substantial advancements in its ability to catalyze both oxygen reduction and evolution reactions (ORR and OER) due to the heteroatom doping by fluorine. For instance, the optimized electrocatalyst (F-NCO-ADC-600) exhibited an onset potential of 0.96 V vs RHE with a half-wave potential of 0.83 V vs RHE for ORR, a comparable performance with the state-of-the-art Pt/C (1.0 and 0.86 V vs RHE, respectively). On a similar note, the same catalyst also displayed an overpotential of 340 mV vs RHE for OER at a current density of 20 mA cm(-2), close to that of a standard RuO2 catalyst (337 mV vs RHE). In the context of polymer electrolytes, the quaternary ammonium-group-grafted chitosan membrane depicted superior ionic conductivity, liquid electrolyte uptake, and mechanical properties, thereby proving to be an efficient anion-conducting polymer electrolyte membrane. The realistic application of the developed electrocatalyst and the polymer electrolyte membrane is demonstrated in the ZAB prototypes. The assembled rechargeable ZAB (RZAB) delivered a power density of 207 mW cm(-2) and maintained high-rate capability and cycling stability, notably in a flexible configuration (f-RZABs). Thus, this work provides a strategy for the rational design of anion-exchange membranes and bifunctional electrocatalysts for f-RZABs.

}, keywords = {anion-conducting polymer electrolytemembrane, F-doping, flexible and rechargeable zinc-air batteries(f-RZABs), oxygen evolution reaction(OER), oxygen reduction reaction (ORR)}, issn = {2574-0962}, doi = {10.1021/acsaem.4c01261}, author = {Kurian, Maria and Ranganath, Suresha P. and Vijayakumar, Vidyanand and Sivadasan, Sneha and Kurian, Rachna Maria and Badiger, Manohar V. and Kurungot, Sreekumar} } @article {49305, title = {High-voltage symmetric supercapacitor electrodes via in situ synthesized multiwalled carbon nanotube-doped perylenebisimide-based donor-acceptor conjugate polymer P(PDI2OD-T2)}, journal = {Journal of Physical Chemistry C}, volume = {128}, year = {2024}, month = {JUL}, pages = {12808-12821}, type = {Article}, abstract = {

This study presents the design and synthesis of a donor-acceptor pi-conjugated polymer composite P(PDI2OD-T2)/MWCNT tailored for high-voltage symmetric supercapacitor applications. The synthesis of P(PDI2OD-T2)/MWCNT was expedited by adopting a novel in situ polymerization technique that modifies the traditional Stille polymerization process. Incorporating approximately 33\% by weight of multiwalled carbon nanotubes (MWCNT) into the polymer matrix, referred to as P-2, significantly enhances its conductivity, surface area, and porosity. These improvements in the material properties contribute to the superior electrochemical performance of the composites by promoting efficient electrolyte ion transport across the electrode-electrolyte interfaces. The symmetric supercapacitor devices fabricated with P-2 electrodes employing both liquid organic (LE-P-2||P-2) and quasi-solid-state gel (QSS- P-2||P-2) electrolytes demonstrate capacitance values of 85.4 and 84.2 F g(-1), respectively, at a current density of 0.25 A g(-1), while operating at a high-voltage window of 3.1 V. Moreover, these devices exhibit robust cycling stability, maintaining approximately 70\% of their initial capacitance over 45,000 cycles with a coulombic efficiency of 96\%. The successful demonstration of a quasi-solid-state symmetric supercapacitor underscores the potential of flexible energy storage solutions, as evidenced by a PMMA LiClO4 gel electrolyte prototype. This flexible device not only maintains structural integrity but also achieves an impressive power density of 18,600 W kg(-1) and an energy density of 112.4 Wh kg(-1), indicating its practical viability for real-world applications.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.4c02345}, author = {Wavhal, Aryan Anurath and Dilwale, Swati and Puthiyaveetil, Priyanka Pandinhare and Kakde, Navnath R. and Prakash, Medha and Kurungot, Sreekumar and Asha, S. K.} } @article {49404, title = {Insights on prussian blue analogue cathode material engineered with polypyrrole surface protection layer for aqueous rechargeable zinc metal battery}, journal = {Small}, year = {2024}, month = {NOV}, type = {Article; Early Access}, abstract = {

One of the key intricacies against using Prussian blue analogues (PBAs) in aqueous batteries is their gradual dissolution in aqueous electrolytes, resulting in inadequate cycling stability. Besides, the rate capability of PBAs is limited due to their poor electrical conductivity. To overcome these challenges, it is essential to tune the physical and chemical properties of PBAs at the nano regime without affecting the inherent charge storage properties, especially at high-voltage operating conditions. Through this work, a strategy is demonstrated to enhance the electrochemical performance of vanadium-based PBA (V-PBA) by surface engineering using a conducting polymer nano-skin (V-PBA/PPy) for aqueous zinc metal batteries. The polypyrrole (PPy) nano-skin over the V-PBA nanoparticles acts as an electron percolation path to ameliorate the poor electronic conductivity of the otherwise pristine V-PBA. Interestingly, the V-PBA with an optimized polypyrrole coating (V-PBA/PPy-2) exhibits an enhanced specific capacity (173 mAh g-1 at 0.10 A g-1) than the pristine V-PBA counterpart (80 mAh g-1) and 85\% capacity retention up to 500 cycles. The DFT calculation confirms the synergistic interaction between PPy and V-PBA and the presence of PPy favors the adsorption of Zn.

}, keywords = {aqueous rechargeable zinc metal battery, DFT, polypyrrole coating, Prussian blue analogue, surface protection layer}, issn = {1613-6810}, doi = {10.1002/smll.202409947}, author = {Puthiyaveetil, Priyanka Pandinhare and Nair, Aathira and Dilwale, Swati and Kurian, Maria and Joshi, Kavita and Kurungot, Sreekumar} } @article {49273, title = {Interlayer space engineering-induced pseudocapacitive zinc-ion storage in holey graphene oxide-bearing vertically oriented MoS2 nano-wall array cathode for aqueous rechargeable Zn metal batteries}, journal = {Small}, volume = {20}, year = {2024}, month = {DEC}, type = {Article}, abstract = {

Transition metal dichalcogenides, particularly MoS2, are acknowledged as a promising cathode material for aqueous rechargeable zinc metal batteries (ARZMBs). Nevertheless, its lack of hydrophilicity, poor electrical conductivity, significant restacking, and restricted interlayer spacing translate into inadequate capacity and rate performance. Herein, the unique porous structure and additional functional groups present in holey graphene oxide (hGO) are taken advantage of to dictate the vertical growth pattern of oxygen-doped MoS2 nanowalls (O-MoS2/NW) over the hGO surface. Compared to conventional graphene oxide (GO), the presence of nano-pores in hGO facilitates the homogeneous dispersion of Mo precursors and provides stronger interaction sites, promoting the uniform vertical alignment of O-MoS2/NW. The synergistic interaction between O-MoS2-NW and hGO translates to enhanced electron conductivity, efficient electrolyte penetration, enhanced interlayer spacing, reduced restacking, and enhanced surface area. As a consequence of precise control of various factors that decide the overall battery performance, a high discharge capacity (227 mAh g(-1) at 100 mA g(-1)) cathode material with significantly lower charge transfer resistance (66 Omega) compared to pristine O-MoS2 (153 Omega) is developed. These findings underscore the potential of hGO as a multifunctional platform for nanoengineering high-performance cathode materials for the next generation of efficient and durable ARZMBs.

}, keywords = {aqueous rechargeable zinc metal battery, holey graphene oxide, hydrophilicity tuning, interlayer space engineering, oxygen-doped MoS2, transition metal dichalcogenide, vertical nanowall}, issn = {1613-6810}, doi = {10.1002/smll.202406926}, author = {Babu, Athira and Dilwale, Swati and Kurungot, Sreekumar} } @article {49251, title = {Iron salicylaldehydate conjugated metal-organic framework for quasi solid-state supercapacitor}, journal = {CHEMICAL ENGINEERING JOURNAL}, volume = {496}, year = {2024}, month = {SEP }, type = {Journal Article}, keywords = {Carbon, conductivity, ELECTROLYTE CONCENTRATION, performance, ROBUST}, issn = {1385-8947}, doi = {10.1016/j.cej.2024.153589}, author = {Mohammed, Abdul Khayum and Pandikassala, Ajmal and Sanchez, Pilar Pena and Gaber, Safa Abdullah and Canossa, Stefano and Kurian, Maria and Xavier, Gigi and He, Yao and Gandara, Felipe and Kurungot, Sreekumar and Shetty, Dinesh} } @article {49262, title = {Phytic acid customized hydrogel polymer electrolyte and prussian blue analogue cathode material for rechargeable zinc metal hydrogel batteries}, journal = {Small}, volume = {20}, year = {2024}, month = {AUG}, type = {Article}, abstract = {

Zinc anode deterioration in aqueous electrolytes, and Zn dendrite growth is a major concern in the operation of aqueous rechargeable Zn metal batteries (AZMBs). To tackle this, the replacement of aqueous electrolytes with a zinc hydrogel polymer electrolyte (ZHPE) is presented in this study. This method involves structural modifications of the ZHPE by phytic acid through an ultraviolet (UV) light-induced photopolymerization process. The high membrane flexibility, high ionic conductivity (0.085 S cm-1), improved zinc corrosion overpotential, and enhanced electrochemical stability value of approximate to 2.3 V versus Zn|Zn2+ show the great potential of ZHPE as an ideal gel electrolyte for rechargeable zinc metal hydrogel batteries (ZMHBs). This is the first time that the dominating effect of chelation of phytic acid with M2+ center over H-bonding with water is described to tune the gel electrolyte properties for battery applications. The ZHPE shows ultra-high stability over 360 h with a capacity of 0.50 mAh cm-2 with dendrite-free plating/stripping in Zn||Zn symmetric cell. The fabrication of the ZMHB with a high-voltage zinc hexacyanoferrate (ZHF) cathode shows a high-average voltage of approximate to 1.6 V and a comparable capacity output of 63 mAh g-1 at 0.10 A g-1 of the current rate validating the potential application of ZHPE. A novel phytic acid (PA) modulated zinc hydrogel polymer electrolyte (ZHPE) as an efficient electrolyte and separator for rechargeable Zn-metal hydrogel batteries (ZMHB) is designed. The zincophilic, and hydrogen bonding characteristics of ZHPE help in regulating uniform dendrite-free Zn-deposition over the Zn anode surface. ZHPE in combination with the developed high-voltage zinc hexacyanoferrate (ZHF) cathode performs as an efficient ZMHB. image

}, keywords = {high voltage cathode, high-conducting gel polymer electrolyte, phytic acid, rechargeable Zn-metal hydrogel batteries, Zn hydrogel polymer electrolyte}, issn = {1613-6810}, doi = {10.1002/smll.202311923}, author = {Dilwale, Swati and Puthiyaveetil, Priyanka Pandinhare and Babu, Athira and Kurungot, Sreekumar} } @article {49080, title = {Role of nitrogen doping in modulating ruthenium nanocatalysts for enhanced electrochemical hydrogen evolution reaction in alkaline medium}, journal = {Chemistry of Materials }, volume = {36}, year = {2024}, month = {APR }, pages = {4262-4274}, type = {Article}, abstract = {

Nitrogen doping has become a fundamental approach to enhance the catalytic performance of carbon materials across various applications. The introduction of nitrogen creates defects and active sites, promoting the formation of small metal particles and strengthening the metal-support interaction within carbon materials. However, the challenge lies in developing sustainable and cost-effective methods for synthesizing nitrogen-doped carbon materials. In this study, we present a sustainable approach for the synthesis of ruthenium on nitrogen-doped carbon catalysts (Ru-CCP) using chitosan as a nitrogen and carbon source. Unlike traditional methods, our process avoids the use of additional nitrogen precursors and templates, streamlining the synthesis while using a renewable resource. The synthesized material exhibits an exceptional performance in the electrochemical hydrogen evolution reaction (HER) in alkaline conditions by achieving a current density of 25 mA cm(-2) at an impressively low overpotential of 46 mV, outperforming Pt/C under similar conditions. The detailed studies on structural and electronic properties of the materials using X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) revealed that the remarkable catalytic activity is upheld by the unique interplay between Ru delta+ and surface nitrogen moieties, notably pyridinic and pyrrolic nitrogen. Here, we demonstrate the control of particle size and electronic environment around the metal atom via the interaction of nitrogen and unravel the role of nitrogen doping in tuning the catalytic performance. In addition, this work offers insights into efficient HER catalyst design and emphasizes the potential of biomass-derived materials like chitosan in advancing clean hydrogen production for renewable energy applications.

}, issn = {0897-4756}, doi = {10.1021/acs.chemmater.3c03169}, author = {Korampattu, Lavanya and Barik, Sidharth and Pandikassala, Ajmal and Urkude, Rajashri R. and Kurungot, Sreekumar and Dhepe, Paresh L.} } @article {49401, title = {Surface-anchored PtNi alloy network over SiO2 (PtNi/SiO2): a versatile carbon-free cathode for proton exchange membrane fuel cells (PEMFCs)}, journal = {ACS Applied Engineering Materials}, volume = {2}, year = {2024}, month = {APR}, type = {Article}, abstract = {

The large-scale commercialization of the PEMFCs is hindered due to the high cost of the Pt-based electrocatalysts (Pt/C) and the low durability associated with the oxidation of the carbon support in Pt/C. Many Pt-based carbon-free electrocatalysts have been explored, exhibiting excellent stability and activity, but the performance is further expected to be improved by developing suitable Pt alloy catalysts based on the carbon-free supports. To explore this possibility, we have developed a PtNi/SiO2\ alloy system, which acts as a carbon-free electrocatalyst exhibiting enhanced activity for the oxygen reduction reaction (ORR). A half-cell study of PtNi/SiO2\ (45 wt\%) shows \~{}4.3 times higher ORR activity compared to the state-of-the-art Pt/C (40\%). The uniform distribution of the PtNi nanoparticles over SiO2\ is the crucial feature of the catalyst. PtNi/SiO2\ shows better durability even after 5000 cycles compared to the state-of-the-art Pt/C. The catalyst shows a negative shift in the half-wave potential (E1/2) by only 5 mV, which is lower than that of the 11 mV drop incurred by Pt/C. Considering this high activity of the PtNi/SiO2\ catalyst for the ORR, we tried to explore the possibility of demonstrating a single-cell PEMFC in the MEA by pairing the catalyst as the cathode along with the Pt/C as the anode. This paired configuration of the single cell is found to be providing promising performance by delivering a current density of 960 mA/cm2\ at 0.60 V and a maximum power density of 835 mW/cm2. Thus, this study outlines the possibility of developing potential alloy combinations of Pt on carbon-free substrates and then deploying them as electrodes for PEMFC applications. In the context of mitigating the carbon corrosion-related issues without compromising the intrinsic activities of the catalysts, the development of suitable alloy combinations on various carbon-free substrates is of significant technological advantages. The formation of the alloy phase along with the fine and uniform distribution of the alloy nanoparticles on the SiO2\ substrate, followed by its successful deployment as the cathode of a single cell, points toward the scope of exploring material developments in this direction.

}, doi = {https://doi.org/10.1021/acsaenm.4c00091}, author = {Kumar, Sachin and Yoyakki, Athira and Kurungot, Sreekumar} } @article {49056, title = {Water-chain mediated proton conductivity in mechanically flexible redox-active organic single crystals}, journal = {Journal of Materials Chemistry A}, volume = {12}, year = {2024}, month = {MAR }, pages = {5866-5874}, type = {Article}, abstract = {

Investigating electrochemical features of proton-conducting organic crystalline materials is relevant in developing efficient energy storage and conversion devices. However, the poor structural flexibility of the crystalline materials at the molecular level often impedes hydrogen bond reorganization of the proton carriers during proton migration, ultimately leading to low ionic conductivity. Here, we report crystals of azobenzene, functionalized with dipicolylamine at both ends (Azo-DPA), which contain an extended hydrogen-bonding network with water molecules in its structure. Interestingly, the crystals display remarkable mechanical flexibility explicitly probed by the nanoindentation technique. The mechanically flexible neutral organic crystals devoid of any acidic moieties (-COOH, -PO3H2, etc.) within the system, exhibit promising proton conductivity (1.63 x 10-4 S cm-1 at 30 degrees C under 95\% relative humidity) which is almost 100 times better compared to the neutral organic systems reported to date. Mechanically flexible redox-active crystalline organic material (Azo-DPA) capable of impressive proton conduction was employed as an electrode material for the first time in an aqueous battery containing Zn2+ ions. The experimental and theoretical studies on the charge storage mechanism revealed the redox activity of the azo (-N 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N-) centers involving reversible insertion/extraction of protons and Zn2+ ions. Ultimately, the electrode displayed a specific capacity similar to 49 mA h g-1 with almost 100\% retention after 1400 cycles, encouraging the scope of redox-active organic crystalline materials for energy storage applications. Investigating the electrochemical features of proton-conducting flexible organic crystalline materials is crucial for the development of efficient energy storage and conversion devices.

}, issn = {2050-7488}, doi = {10.1039/d3ta05797f}, author = {Hossain, Munshi Sahid and Ghosh, Meena and Mondal, Amit and Ajmal, P. and Saha, Monochura and Reddy, C. Malla and Kurungot, Sreekumar and Bandyopadhyay, Subhajit} } @article {49779, title = {3D-architectured Pt-carbon electrodes for PEM fuel cells with tuned porosity and ionomer distribution-a micromanaged approach for improving activation, ohmic, and mass transport characteristics}, journal = {ACS Applied Energy Materials}, volume = {8}, year = {2025}, month = {DEC }, pages = {18158-18170}, type = {Article}, abstract = {

The conventional catalyst layer in Proton Exchange Membrane Fuel Cells (PEMFCs) suffers the limitation of masked active sites, hindered proton transportation, excessive water clogging, and irregular ionomer distribution, resulting in an underutilized catalyst. To overcome these challenges, an innovative catalyst layer (CL) is constructed by aligning Vulcan carbon (VC) particles along a 3D carbon nitride interconnected network originating from a melamine sponge. This forms a robust scaffold rich in anchoring sites like sulfur and nitrogen for the Pt nanoparticle. The resultant 3D CL exhibits a doubled through-plane proton transport conductivity from 23 to 41 mS cm-1, delivering a 17.3\% increase in the current density at 0.60 V compared to a conventional VC CL. This strategy enables enhanced ionomer incorporation, yielding a 19.60\% enhancement in the ionomer coverage over the Pt without sacrificing the porosity, as verified by a mercury porosimeter. Kelvin probe force microscopy confirms a more uniform electron density across the 3D CL, in contrast to the traditional CL, suggesting uniform coverage. The advanced porosity and structure of the 3D CL allow the mass transport regions to shift to higher current densities, with an increase of 0.30 A cm-2 at 0.50 V compared to the VC CL. The improved ionomer coverage also demonstrates 19\% lower voltage degradation at 0.80 A cm-2. Further, the impedance mapping across the entire current range graphically illustrates the 3D CL{\textquoteright}s advantage in the activation, Ohmic, and mass transport regions, showing a parabolic profile with a flattened bottom attributed to the reduced Ohmic resistance and its extension to delay the mass transport losses.

}, keywords = {3D-structured catalyst layer, impedancemapping, ionomer coverage, low-temperature proton exchange membranefuel cell (LT-PEMFC), mercury porosimeter, proton resistance, triplephase boundary (TPB)}, issn = {2574-0962}, doi = {10.1021/acsaem.5c03025}, author = {Singh, Mayank U. and Mathew, Grigory and Kurungot, Sreekumar} } @article {49514, title = {Advances in polymer electrolyte design strategies for highly efficient supercapacitors and Zn-based batteries}, journal = {Chemical Communications}, volume = {61}, year = {2025}, month = {MAY }, pages = {6864-6881}, type = {Article}, abstract = {

Electrolytes play a crucial role in the performance of electrochemical energy storage systems, such as batteries and supercapacitors. Their main function is to act as a medium for ion transport between the electrodes, which is essential for the charge and discharge processes. Beyond this, the electrochemical performance of the device is strongly affected by the various properties of the electrolytes such as their ionic conductivity, chemical, thermal and electrochemical stability, chemical compatibility, etc. The intrinsic limitations of the aqueous electrolytes such as their decomposition during high voltage operations has led to the development of better electrolytes for batteries and supercapacitors. These included non-aqueous electrolytes, inorganic solid-state electrolytes, and gel polymer electrolytes. This feature article reviews the various approaches to designing a highly efficient polymer electrolyte for the targeted application along with the suitable device fabrication strategy adopted in the current literature to achieve a balanced electrochemical performance compared with a liquid electrolyte-based device.

}, issn = {1359-7345}, doi = {10.1039/d5cc00174a}, author = {Puthiyaveetil, Priyanka Pandinhare and Babu, Athira and Kurian, Maria and Kurungot, Sreekumar} } @article {49772, title = {Anode|electrolyte|cathode interface engineering to develop a robust zinc metal hydrogel battery}, journal = {Journal of Materials Chemistry A}, volume = {13}, year = {2025}, month = {DEC }, pages = {41105-41121}, type = {Article}, abstract = {

The poor electrode-electrolyte interfaces in quasi-solid-state zinc metal batteries often hinder Zn2+ ion transport due to the poor compatibility of the gel electrolyte with the electrodes. This report proposes a dual-interface engineering strategy across the anode, cathode, and separator using a single hydrogel polymer electrolyte (HPE). The integration of vanadyl phosphate functionalized carbon nanotubes (VP/fCNT) into a commercial glass fiber (GF) separator, followed by a thin hydrogel coating and UV-light photopolymerization, resulted in a dual-interface engineered cathode-separator-electrolyte structure (VP/IC-EGF). To mitigate the dendritic growth, an artificial solid electrolyte interface was developed on Zn foil (AEI@Zn). The engineered GF (EGF) demonstrates a room-temperature conductivity of 6.5 mS cm-1 and a high electrochemical stability window of 2.4 V vs. Zn|Zn2+. The symmetric cell with AEI@Zn|EGF|AEI@Zn exhibits exceptional plating/stripping stability over 1400 h at a current density of 0.1 mA cm-2 and a capacity of 0.1 mAh cm-2. Moreover, the low-volume cell (AEI@Zn \& Vert;VP/IC-EGF), featuring the dual-interface-engineered cathode-separator-electrolyte, demonstrates outstanding cycling stability with over 3000 charge-discharge cycles at a current rate of 1.0 A g-1, retaining 98-99\% of its initial capacity and showing high coulombic efficiency. These findings underscore the significant impact of interface engineering on enhancing the performance of ZMBs.

}, issn = {2050-7488}, doi = {10.1039/d5ta04128g}, author = {Dilwale, Swati and Babu, Athira and Kanheerampockil, Fayis and Torris, Arun and Puthiyaveetil, Priyanka Pandinhare and Bhat, Suresh and Kurungot, Sreekumar} } @article {49780, title = {Binder-free in situ interface reconstruction of NiMoO4 nanorods over Ni(OH)2 nanosheets for efficient urea oxidation}, journal = {Advanced Sustainable Systems}, volume = {9}, year = {2025}, month = {DEC}, type = {Article}, abstract = {

Replacing the energy-intensive oxygen evolution reaction (OER) with the urea oxidation reaction (UOR) in electrochemical water splitting offers simultaneous green hydrogen production and urea-rich wastewater oxidation, enhancing energy efficiency and economic viability. In this study, a non-noble metal-based binder-free NiMoO4/Ni(OH)2/NF electrocatalyst is developed, featuring NiMoO4 nanorods anchored on Ni(OH)2 nanosheets. This unique morphology facilitates a highly active in situ reconstructed interface, delivering a current density of 134 mA cm-2 at 1.40 V (vs RHE) in 1 m KOH with 0.33 m urea, significantly outperforming its individual components. The catalyst demonstrates excellent stability over 50 h at 30 mA cm-2. When integrated into an anion exchange membrane urea electrolyser (13 cm2 area) with Pt@C/NF as the HER cathode, the system achieves 192 mA cm-2 at 1.60 V. The post-UOR studies confirm the presence of an amorphous NiMoO4-crystalline Ni(OH)2 interface, which plays a key role in enhancing the availability of the active sites to enhance the UOR performance. The improved electrochemical performance of the engineered catalyst can be ascribed to the in situ reconstructed amorphous-crystalline interface, optimal hydrophilicity, reduced charge transfer resistance, and the distinct morphology. This strategy offers a promising pathway for developing highly active electrocatalysts for energy conversion applications.

}, keywords = {AEM, electrolyser, OWS, tomography, UOR, wastewater}, issn = {2366-7486}, doi = {10.1002/adsu.202500883}, author = {Kumar, Yogesh and Barik, Sidharth and Kharabe, Geeta Pandurang and Torris, Arun and Singh, Mayank U. and Mohan, S. and Galave, Chaitanya and Tekawadia, Jyoti and Kanawade, Rajesh and Kurungot, Sreekumar} } @article {49802, title = {Defect-rich CoFe-alloy with engineered carbon support for high-performance rechargeable Zn-air batteries}, journal = {Small}, volume = {21}, year = {2025}, month = {SEP}, type = {Article}, abstract = {

Defect-rich CoFe-alloy with engineered carbon support is synthesized as a bifunctional cathode, coupled with a modified electrode fabrication technique, for rechargeable zinc-air batteries (RZABs). The CoFe(2:1)/N-rGCNT-catalyst is synthesized by annealing graphene oxide (GO), cobalt and iron acetate, and melamine, leading to the in situ formation of CoFe alloy-encapsulated CNTs. This resulted in a unique layer-separated Fe-rich skin@CoFe alloy decorated nitrogen-doped graphene (NGr) with CoFe-encapsulated CNTs. The interplay of line defects, enhanced conductivity, and electronic modulation underpins electrocatalyst{\textquoteright}s performance. Electrochemical analysis revealed an onset potential of 955 mV vs RHE, a half-wave potential of 835 mV vs RHE for oxygen reduction reaction (ORR) and an overpotential of 340 mV for oxygen evolution reaction (OER), yielding a Delta E of 0.73 V, comparable to the reported catalysts. The 3D X-ray microtomography simulations suggest improved air permeability of CoFe(2:1)/N-rGCNT facilitates easier gas diffusion, contributing in better device performance. The RZAB with CoFe(2:1)/N-rGCNT-cathode exhibited a peak power density of 171.3 mW cm(-)2, surpassing 140.8 mW cm(-)2 obtained from a cell based on Pt/C-cathode. The Co/N-rGCNT-based battery achieved a stable discharge profile at 10 mA cm(-)2 with a specific capacity of 650 mAh g(-)(1)Zn, and in rechargeable mode, achieved 140 h of high-rate charge-discharge cycling capability.

}, keywords = {3D tomography, N-doping, alloy encapsulated structure, device demonstration, grain boundaries, oxygen reduction and evolution reactions, rechargeable zinc-air battery}, issn = {1613-6810}, doi = {10.1002/smll.202505342}, author = {Kharabe, Geeta Pandurang and Barik, Sidharth and Torris, Arun and Maria, Anit and Kumar, Yogesh and Kurungot, Sreekumar} } @article {49596, title = {Hot injection assisted electronically modulated twin and grain boundary rich sub-2 nm pt3co alloy resistant to phosphate ion for PEMFCs}, journal = {Small}, volume = {21}, year = {2025}, month = {MAY}, type = {Article}, abstract = {

Modulation of the electronic d-band center, structural defects (line defects), and particle size of Pt3Co alloy electrocatalyst have huge significance in elevating its electrochemical oxygen reduction reaction activity. Deviating from traditional high-temperature strategies, the current work focuses on ripening these benefits by implying a simple economically viable hot-injection-assisted modified polyol process. A conclusive control over decrementing particle size starting from 2.7 to 1.3 nm, an increasing degree of strain (twin boundary), and shifting of the d-band center away from the Fermi level are obtained via varying the temperature to which the solution is injected. The catalyst prepared via the injection at 200 degrees C (Pt3Co(1.3 t,g-b)/fVC-200) has delivered an electrochemical surface area of 84 m(2) g(Pt)(-1) with the onset and half-wave potentials of 0.980 and 0.858 V, respectively, versus RHE and a limiting current of -6.0 mA cm(-2) with stability till 20k cycles. In the high-temperature proton exchange membrane fuel cell Pt3Co(1.3 t,g-b)/fVC-200-based cell has outperformed Pt/C rendering 600 mWcm(-2) under H-2-Air compared to 529 mWcm(-2) of Pt/C with 20\% lower Pt loading and double the stability due to enhanced resistance toward phosphoric acid for accelerated voltage cycling. A similar enhancement is seen while employing the catalyst for low-temperature fuel cells.

}, keywords = {electrocatalyst, grain boundary, hot injection synthesis, modified polyol process, oxygen reduction reaction, proton exchange membrane fuel cell, Pt3Co alloy, twin boundary, valance band X-ray photoelectron spectroscopy}, issn = {1613-6810}, doi = {10.1002/smll.202500954}, author = {Singh, Mayank U. and Jadhav, Swapnil D. and Shivankar, Bhavana R. and Pandikassala, Ajmal and Kumar, Yogesh and Krishnamurty, Sailaja and Vinod, C. P. and Kurungot, Sreekumar} } @article {49573, title = {Hydrogel electrolyte-mediated in situ Zn-anode modification and the Ru-RuO2/NGr-coated cathode for high-performance solid-state rechargeable Zn-air batteries}, journal = {ACS Applied Materials \& Interfaces}, volume = {17}, year = {2025}, month = {JAN}, pages = {3188-3204}, type = {Article}, abstract = {

This work aims to deal with the challenges associated with designing complementary bifunctional electrocatalysts and a separator/membrane that enables rechargeable zinc-air batteries (RZABs) with nearly solid-state operability. This solid-state RZAB was accomplished by integrating a bifunctional electrocatalyst based on Ru-RuO2 interface nanoparticles supported on nitrogen-doped (N-doped) graphene (Ru-RuO2/NGr) and a dual-doped poly(acrylic acid) hydrogel (d-PAA) electrolyte soaked in KOH with sodium stannate additive. The catalyst shows enhanced activity and stability toward the two oxygen reactions, i.e., oxygen reduction and evolution reactions (ORR and OER), with a very low potential difference (Delta E) of 0.64 V. The computational insights bring out the electronic factors contributing to the enhanced catalytic activity of Ru-RuO2/NGr based on the charge density difference (CDD) between the interfaces. The disadvantages of the existing solid-state RZABs, such as their limited lifespan brought on by passivation, dendritic growth, corrosion, and shape change, have also been taken into account. The introduction of the stannate additive to the electrolyte induced an in situ Zn-anode modification, which subsequently improved the interfacial stability of the ZABs and, hence, the battery life cycles. The experimental observations reveal that, during the charging process, the Sn nanoparticles enable the homogeneous Zn deposition on the surface of the anode. Thus, the in situ Zn-anode surface modification assisted in achieving a high-rate cycle capability, viz., the homemade catalyst-based system exhibited continuous charge-discharge cycles for 20 h at a current density of 2.0 mA cm-2, with each cycle lasting for 5 min.

}, keywords = {Bifunctional Electrocatalyst, Core-ShellStructure, DFT study, electrolyte additive, Hydrogel, solid-state rechargeable zinc-airbattery, X-ray absorption spectroscopy}, issn = {1944-8244}, doi = {10.1021/acsami.4c14231}, author = {Kharabe, Geeta Pandurang and Verma, Tushar and Barik, Sidharth and Urkude, Rajashri R. and Ayasha, Nadeema and Ghosh, Biplab and Krishnamurty, Sailaja and Kurungot, Sreekumar} } @article {49694, title = {In situ engineered triple phase boundary enhancement in 3D structured carbon supported catalyst for high-temperature PEMFC}, journal = {Journal of Materials Chemistry A}, volume = {13}, year = {2025}, month = {JUL}, pages = {21847-21863}, type = {Article}, abstract = {

Enhancing platinum (Pt) utilization in polymer electrolyte membrane fuel cells (PEMFCs) requires optimizing the catalyst support microstructures to expand the triple-phase boundary (TPB). A promising method has been reported here which employs a three-dimensional (3D) catalyst support with an in situ-generated ionomer interface from preadmitted monomer molecules, potentially replacing the traditional Nafion ionomers. The small-sized monomers infiltrate the catalyst{\textquoteright}s pores, and UV curing polymerizes them into an extended interfacial network within the 3D carbon support. The single-cell analysis of the membrane electrode assemblies (MEAs) in high-temperature PEMFCs (HT-PEMFCs) using phosphoric acid-doped polybenzimidazole (PBI) membranes highlights the effectiveness of this approach. The strategy helps to achieve a current density of 1.06 A cm-2 and 0.49 A cm-2 at 0.60 V in H2-O2 and H2-air feed conditions, respectively. These values represent a significant improvement over the conventional Nafion ionomer-based MEAs, which exhibit current densities of 0.87 A cm-2 and 0.40 A cm-2 under H2-O2 and H2-air feeds, respectively, when utilizing a platinum-supported carbon (Pt/C) catalyst. When Pt nanoparticles are decorated on a high-surface-area, porous 3D interconnected carbon support synthesized via the carbonization of the polydopamine-coated melamine foam (Pt/3DPDC), the conventional Nafion ionomers tend to block the nanopores in the 3D carbon supports, leading to the underutilization of the Pt active sites. In contrast, the in situ ionomer approach enabled the system to deliver 0.93 A cm-2 at 0.60 V H2-O2 feed conditions, which is significantly higher than 0.38 A cm-2 obtained with the Nafion-based ionomers under similar conditions. This approach successfully makes use of the Pt active sites present in the nanopores and tackles the issues of mass transfer and reactant distribution, both of which are essential for expanding fuel cells from single cells to stacks. The exhibited method emphasizes how crucial it is to develop process-friendly electrocatalysts and complementary electrode manufacturing techniques in order to advance the PEMFC performance through a novel scientific path.

}, issn = {2050-7488}, doi = {10.1039/d5ta02793d}, author = {Pandikassala, Ajmal and Jadhav, Swapnil D. and Kurian, Maria and Kurungot, Sreekumar} } @article {49504, title = {Pt-based 3D electrocatalyst with process-friendly features for PEMFCs possessing fast activation and improved mass-transfer properties}, journal = {Advanced Sustainable Systems}, volume = {9}, year = {2025}, month = {APR}, type = {Article}, abstract = {

Polymer-electrolyte-membrane fuel cells (PEMFCs) face the challenges like slow oxygen reduction reaction (ORR) kinetics and limited mass transport at high current densities, which affects their performance. The efficient water removal from the cathode is essential to improve oxygen diffusion. Addressing this, a catalyst is presented with platinum (Pt) nanoparticles distributed within a 3D carbon network (Pt/3DPDC) derived from the polydopamine-coated melamine foam. This unique architecture enhances Pt utilization and water management due to its high porosity and ample free spaces, providing a process-friendly feature for the electrode under PEMFC conditions. The pores and accessible texture of the 3D polydopamine derived carbon (3DPDC) framework facilitate ionomer uptake during the electrode fabrication, extending the active triple-phase boundary and improving the membrane electrode assembly (MEA) performance. The high porosity of Pt/3DPDC is mitigated by adding a small amount of commercial fuel cell catalayst (Pt/C), which maintains the effective catalyst number density per unit area by utilizing the excess porosity of the 3DPDC framework. This controlled interplay of the unique catalyst structure and spatially confined distribution of Pt/C within the Pt/3DPDC framework offers fast activation, reduced electrode flooding, and improved current densities across the operating potential window. This carefully engineered catalyst, designed through bottom-up strategies, is a promising electrocatalyst for practical PEMFC applications.

}, keywords = {Oxygen Evolution Reaction, oxygen reduction reaction, rechargeable flexible zinc-air battery}, issn = {2366-7486}, doi = {10.1002/adsu.202400904}, author = {Pandikassala, Ajmal and Nadumattuvayil, Varsha and Singh, Mayank U. and Jadhav, Swapnil D. and Yoyakki, Athira and Kurungot, Sreekumar} } @article {49862, title = {A Pt-Based Carbon-Free Cathode with Embedded Oxygen Nanoreservoirs: A Promising Approach for Oxygen Buffering to Aid Oxygen Reduction Reactions of PEMFCs}, journal = {ACS Catalysis}, volume = {15}, year = {2025}, month = {NOV}, pages = {19677-19694}, type = {Article}, abstract = {

For practical applications of proton exchange membrane fuel cells (PEMFCs), the system needs to be operated by employing air in the cathode instead of pure oxygen (O2). This makes it necessary to develop innovative electrode engineering solutions so that the system can function well even in oxygen-lean environments under the realistic working conditions of PEMFCs. Taking this into account, we introduce Pt/SiO2@CeO2-30\%, an engineered electrocatalyst with potentially generated oxygen vacancies (Ov), which can immensely contribute toward the enhancement in the O2 availability in oxygen-lean conditions like the air feed conditions, allowing an effective control of the overpotential related to the oxygen reduction reactions (ORRs) at the electrode level. The meticulously crafted Pt-CeO2 interface serves as one of the appreciable structural attributes of the present catalyst, facilitating oxygen spillover toward the Pt environment, aided by the creation of the immense Ov along the nano CeO2 phase of the catalyst. In addition to the benefit of addressing the oxygen-lean conditions and overcoming the limitations of the state-of-the-art catalysts, usage of a noncarbonaceous support like SiO2 to house the Pt and CeO2 nanoparticles has been anticipated to lessen the corrosion problems, a major drawback associated with the carbon-based ORR catalysts. Apart from this, a significant contribution of SiO2 to the self-humidification of the ionomer interface plays a crucial role in enabling the MEA to work under low relative humidity conditions, which can be attributed to an additional benefit of the current composition of the catalyst. The catalyst demonstrated a promising ORR performance with a substantial improvement in H2-air feed circumstances and better corrosion resistance when tested with a membrane electrode assembly (MEA) in a single-cell configuration, illustrating the practical feasibility in a realistic system-level validation.

}, keywords = {carbon corrosion, carbon-free electrocatalyst, oxygen buffering, oxygen reductionreaction, oxygen spill over, protonexchange membrane fuel cell}, issn = {2155-5435}, doi = {10.1021/acscatal.5c06455}, author = {Yoyakki, Athira and Kumar, Sachin and Pandikassala, Ajmal and Jadhav, Swapnil D. and Vinod, C. P. and Kurungot, Sreekumar} } @article {49531, title = {Self-supported super-hydrophilic interconnected nanospikes and particles of MoS2-Ni3S2/NF with optimum d-band center for anion exchange membrane water electrolyzer}, journal = {Advanced Sustainable Systems}, volume = {9}, year = {2025}, month = {MAR}, type = {Article}, abstract = {

There is an imperative need for highly efficient electrocatalysts for cost-effective hydrogen production. Herein, a self-supported, hybrid composite as a bifunctional electrocatalyst is introduced. This is achieved by in situ growth of MoS2-Ni3S2 on nickel foam (NF), designated as MoS2-Ni3S2/NF, synthesized by a facile one-step hydrothermal synthesis method. MoS2-Ni3S2/NF exhibits low overpotentials of only 187 and 146 mV for OER and HER, respectively, to achieve a current density of 10 mA cm-2 in 1 M KOH. The practical application of the designed bifunctional electrocatalyst is verified by constructing the MoS2-Ni3S2/NF || MoS2-Ni3S2/NF symmetrical membrane electrode assembly (MEA) of 4 cm2 working area for the anion exchange membrane water electrolyzer. The system shows continuous electrolysis for the monitored 48 h duration. For OER, an optimum d-band center of -1.66 eV for the heterostructure is calculated from the Density Functional Theory (DFT) studies. The factors like the unique structure of the electrocatalyst, enhanced hydrophilicity, improved electrochemically accessible number of sites (ECASs), and optimum d-band center, are expected to be the primary contributors to the system{\textquoteright}s improved performance. Thus, the present finding unveils a straightforward synthesis approach for creating a stable electrocatalyst for advancing commercial water electrolysis in the realm of renewable electrochemical energy conversion.

}, keywords = {AEM, d-band center, electrolyzer, HER, OER}, issn = {2366-7486}, doi = {10.1002/adsu.202400957}, author = {Kumar, Yogesh and Barik, Sidharth and Samudre, Nikhil S. and Kharabe, Geeta Pandurang and Chauhan, Inderjeet and Manna, Narugopal and Bhat, Suresh and Kurungot, Sreekumar} } @article {49793, title = {Tunable, amine-functionalized porous silica catalyst for CO2 transformation into cyclic organic carbonates at atmospheric pressure}, journal = {Chemistry-A European Journal}, volume = {31}, year = {2025}, month = {AUG }, type = {Article}, abstract = {

A silica catalyst with characteristic features of broad pore size distribution, large pore width and tunable basic sites was synthesized by a one-step green co-condensation synthesis method analogous to SBA-15 synthesis. The surface chemical features of the above catalyst were explored by XPS, N-2 and CO2 adsorption and desorption experiments. The catalyst showed 90\% conversion of styrene oxide (SO) with nearly complete selectivity toward styrene carbonate (SC) in 7 hours under a solvent-free condition at a temperature of 120 degrees C with the aid of co-catalyst tetrabutylammonium bromide (TBAB). Moreover, the catalyst demonstrates versatility with various epoxide substrates, providing valuable insights into the cycloaddition reaction under ambient pressure conditions involving carbon dioxide. The mechanistic details of the catalytic conversion were investigated by the in-situ DRIFT studies and reported here.

}, keywords = {CO2 fixation, cyclic organic carbonates, heterogeneous catalysis, in-situ FTIR}, issn = {0947-6539}, doi = {10.1002/chem.202500873}, author = {Gorai, Twinkle and Thanasekar, Chandragopal and Kumar, Pawan and Babu, Athira and Kurungot, Sreekumar and Vinod, C. P.} } @article {49853, title = {UV-modified polydopamine zincophilic protective layer for durable and alkaline-stable zinc anodes in zinc-air batteries}, journal = {Journal of Materials Chemistry A}, volume = {13}, year = {2025}, month = {NOV}, pages = {38928-38944}, type = {Article}, abstract = {

Rechargeable zinc-air batteries (ZABs) are promising for flexible energy storage due to their high specific energy, safety, and cost-effectiveness. However, the snags of the zinc (Zn) anode, like ineluctable passivation and dissolution in strongly alkaline electrolytes, limit the discharge and cycling performance of the battery. Electroless plating can be employed to coat the Zn foil with a polydopamine (PDA) layer, leveraging PDA{\textquoteright}s strong adsorption on the Zn via bidentate bonds. Due to PDA{\textquoteright}s poor stability in alkaline media, ultraviolet (UV)-induced secondary modifications are conducted to obtain Zn@PDA-UV electrodes with enhanced mechanical and chemical stability. The Zn@PDA-UV layer regulates Zn dendrite growth and suppresses hydrogen evolution and passivation. The zincophilic groups on the Zn@PDA-UV anode suppressed the zincate cross-over, enhancing the recyclability of the ZABs. When paired with commercial catalysts to assemble alkaline ZABs, the battery displayed excellent cycling stability of 75 h. A highly stable anion-conducting polymer electrolyte membrane (PXM) was prepared from the polymer blend of polyvinyl alcohol (PVA), xanthan gum, and METAC monomers to tailor a high-performing flexible ZAB with suppressed zincate crossover. The flexible ZAB, integrating the modified Zn anode and PXM, shows a stable cycling profile under various bending angles, demonstrating excellent mechanical and electrochemical durability.

}, issn = {2050-7488}, doi = {10.1039/d5ta05126f}, author = {Kurian, Maria and Pandikassala, Ajmal and Kurungot, Sreekumar} } @article {50016, title = {High-performance sultone-modified PVA/PAMPS semi-IPN hydrogels for proton exchange membranes}, journal = {Journal of Applied Polymer Science}, volume = {143}, year = {2026}, month = {APR}, type = {Article}, abstract = {

Hydrogel membranes composed of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and sultone-modified poly(vinyl alcohol) (PVA) were successfully synthesized and evaluated as promising proton-conducting materials. A key advantage involves the premodification of PVA with 1,3-propane sultone to introduce sulfonic acid groups, thereby imparting proton conductivity to the PVA backbone. This sultone-modified PVA was then physically entangled within a PAMPS cross-linked network to form novel semi-interpenetrating network (semi-IPN) hydrogels. This synergistic design leverages the excellent film-forming and mechanical properties of PVA with the high proton conductivity inherent to PAMPS. The synthesized membranes exhibited robust mechanical properties, with tensile strengths ranging from 5 to 30 MPa and percentage elongations between 200\% and 400\%, depending on their humidity content. These hydrogel membranes demonstrated proton conductivities ranging from 0.6 to 4.3 x 10-2 S cm-1. The activation energy for proton conduction was found to be as low as 3.5 kJ mol-1, significantly lower than that of the commercial benchmark membrane, Nafion 117 (12 kJ mol-1). These findings underscore the potential of these novel PAMPS/sultone-modified PVA semi-IPN hydrogel membranes for advanced fuel cell applications.

}, keywords = {batteries and fuel cells, functionalization of polymers, Gels, membranes, polyelectrolytes}, issn = {0021-8995}, doi = {10.1002/app.70462}, author = {Patwadkar, Manjusha V. and Illathvalappil, Rajith and Torris, Arun and Francis, Sifa C. and Kurungot, Sreekumar and Badiger, Manohar V.} } @article {50046, title = {Proton conductivity in a copper(II) bipyridine glycoluril complex: the synergistic role of coordinated water and hydrogen-bonded networks}, journal = {Inorganica Chimica Acta}, volume = {594}, year = {2026}, month = {MAY}, pages = {123063}, type = {Article}, abstract = {

A dinuclear complex of copper(II) and bipyridine glycoluril (BPG) ligand is synthesized, characterized, and structurally examined by single-crystal X-ray diffraction. The complex [Cu2(BPG)2(NO3)2(H2O)4](NO3)2 center dot 5H2O (complex (1)) further forms a supramolecular network sustained by H-bonds between NH/C=O of BPG, coordinated/free water molecules, and nitrate anions. The complex exhibits a proton conductivity of 5.99 x 10_ 3 S center dot cm_ 1 at 90 degrees C and 95 \% relative humidity (RH) with activation energy value Ea 0.35 eV, suggesting the Grotthuss proton transport mechanism. This value is consistent with those reported for proton-conducting systems in which coordinated water molecules play a critical role in facilitating efficient proton hopping across hydrogen-bonded networks.

}, keywords = {Coordinated water, Copper(II) complex, H -bonding, proton conduction, Supramolecular networks}, issn = {0020-1693}, doi = {10.1016/j.ica.2026.123063}, author = {Khatavkar, Medhavi D. and Panday, Rishukumar and Singh, Mayank U. and Kurungot, Sreekumar and Kumbhar, Avinash S.} } @article {49835, title = {Self-healing hydrogel electrolyte enabled by dynamic polar covalent and noncovalent interactions for high-performance rechargeable zinc-metal batteries: a leap toward sustainable energy storage}, journal = {Advanced Energy Materials}, volume = {16}, year = {2026}, month = {JAN}, type = {Article}, abstract = {

Hydrogel polymer electrolytes with superior multifunctional properties are promising alternatives to aqueous electrolytes for resolving interfacial issues in rechargeable zinc-metal batteries. In this study, an intrinsic self-healing hydrogel polymer electrolyte (PHBC-4) is synthesized, engineered through an integrated approach involving the polar covalent (B \& horbar;O bond), hydrogen-bond (polyvinyl alcohol-hydroxypropyl methylcellulose interface), and coordination-type (Zn \& horbar;O) interactions to enable self-healing functionality. The PHBC-4 has demonstrated high ionic conductivity (4.6 x 10-2 S cm-1), good oxidative stability (2.3 V vs Zn|Zn2+), a high cation transference number (0.89), superior tensile strength (0.32 MPa), and an impressive healing efficiency of 93\% achieved just within 5 min, confirming its robust self-healing capability. In Zn||Zn symmetric cells, it effectively suppresses dendrite growth, ensuring stable cycling for over 1032 h with an areal capacity of 1.0 mAh cm-2 at a current density of 1.0 mA cm-2. When paired with a Zn-doped MnO cathode in the rechargeable homemade pouch cell, the system delivers a high specific capacity of 160 mAh g-1 at 0.10 A g-1 and cycling stability up to 493 charge-discharge cycles at 2.0 A g-1. The self-healing ability of PHBC-4 HGPE is confirmed in a homemade pouch cell via OCV and charge-discharge tests, demonstrating stable performance. The DFT studies confirm molecular-level interactions within the hydrogel heterostructure.

}, keywords = {dendrite inhibition, flexible rechargeable zinc metal battery, high cation transference number, self-healing hydrogel polymer electrolyte}, issn = {1614-6832}, doi = {10.1002/aenm.202502883}, author = {Puthiyaveetil, Priyanka Pandinhare and Kurian, Rachna Maria and Samudre, Nikhil S. and Balasubramanian, Rajalakshmi and Torris, Arun and Pockil, Fayis Kanheeram and Bhat, Suresh and Ajithkumar, T. G. and Krishnamurty, Sailaja and Kurungot, Sreekumar} }