@article { ISI:000329137400042, title = {Selective imaging of quorum sensing receptors in bacteria using fluorescent Au nanocluster probes surface functionalized with signal molecules}, journal = {ACS Applied Materials \& Interfaces}, volume = {5}, number = {24}, year = {2013}, month = {DEC}, pages = {13076-13081}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Fluorescent ultrasmall gold clusters decorated with bacterial quorum sensing signal molecules, acyl homoserine lactone, are synthesized. These fluorescent probes are found to have emission in the near-infrared spectral region advantageous for bioimaging. Imaging studies using different. strains of bacteria with and without acyl homoserine lactone receptors with the aid of confocal microscopy have shown that the probe interacts preferentially with cells possessing these receptors. This indicates that, with appropriate surface functionalization, the Au clusters can be used for receptor specific detection with enhanced selectivity.

}, keywords = {Au nanoclusters, Biosensor, fluorescence imaging, quorum sensing}, issn = {1944-8244}, doi = {10.1021/am404093m}, author = {Mukherji, Ruchira and Samanta, Anupam and Illathvalappil, Rajith and Chowdhury, Somak and Prabhune, Asmita and Devi, R. Nandini} } @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:000340768000019, title = {New approach of blending polymeric ionic liquid with polybenzimidazole (PBI) for enhancing physical and electrochemical properties}, journal = {Journal of Materials Chemistry A}, volume = {2}, number = {35}, year = {2014}, month = {JUN}, pages = {14449-14458}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Although the use of ionic liquids (IL) in polymeric membranes is known to elevate the electrochemical performance for proton exchange membrane-based fuel cells (PEMFC), they suffer from drawbacks such as IL drain and lowering in mechanical properties that lead to deterioration in PEMFC performance. To mitigate these issues, we report, for the first time, the use of polymeric ionic liquid (PIL), namely, poly(diallyl dimethyl ammonium trifluoride methane sulphonate) (P[DADMA][TFMS]) to be blended with polybenzimidazole (PBI-I) as a membrane material for PEMFC. PBI-I and (P[DADMA][TFMS]) were chosen because they form miscible blends and are suitable for acid doping as a matrix, which can eventually be used as proton conductor. The structure, miscibility and inter-polymer interactions were studied by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). The increase in proton conduction in comparison to the PBI membranes was observed due to the presence of ionic groups of PILs in blend membranes. With the increase in PIL content, the proton conductivity of the composite membranes gradually increased from 0.04 S cm(-1) for PBI to 0.07 S cm(-1) for the blend membrane at 150 degrees C. The MEAs were fabricated with PBI-I, PBI-PIL15, PBI-PIL25 and PBI-PIL35. Corresponding single cells were successfully tested at temperatures of 160 degrees C. The maximum power density and current density obtained were 515 mW cm(-2) and 1632 mA cm(-2), respectively, for PBI-PIL25-based MEA.

}, issn = {2050-7488}, doi = {10.1039/c4ta02184c}, author = {Rewar, Anita S. and Chaudhari, Harshal D. and Illathvalappil, Rajith and Sreekumar, K. and Kharul, Ulhas K.} } @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: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 {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: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 {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: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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {48448, title = {Hydroxide ion-conducting viologen-bakelite organic frameworks for flexible solid-state zinc-air battery applications}, journal = {Nanoscale Horizons}, volume = {8}, year = {2023}, month = {JAN }, pages = {224-234}, type = {Article}, abstract = {

Adaptable polymer-based solid-state electrolytes can be a game-changer toward safe, lightweight flexible batteries. We present a robust Bakelite-type organic polymer covalently decked with viologen, triazine, and phenolic moieties. Its flexible structure with cationic viologen centers incorporates counter-balancing free hydroxide ions into the polymeric framework. By design, the aromatic groups and heteroatoms in the framework can be activated under an applied potential to prompt a push-pull drive, setting off the towing of hydroxide ions via weak electrostatic, van der Waals, and hydrogen-bond interactions. The frontier orbitals from a DFT-modeled structure certify this. The hydroxyl-polymer requires minimal KOH wetting to maintain a humid environment for Grotthuss-type transport. The hydroxide ion conductivity reaches a value of 1.4 x 10(-2) S cm(-1) at 80 degrees C and 95\% RH, which is retained for over 15 h. We enhanced its practical utility by coating it as a thin solid-state separator-cum-electrolyte on readily available filter paper. The composite exhibits a conductivity of 4.5 x 10(-3) S cm(-1) at 80 degrees C and 95\% RH. A zinc-air battery (ZAB) constructed using this polymer-coated paper as electrolyte yields a maximum power density of 115 mW cm(-2) and high specific capacitance of 435 mA h g(-1). The power density recorded for our ZAB is among the best reported for polymer electrolyte-based batteries. Subsequently, the flexible battery fabricated with IISERP-POF11_OH@FilterPaper exhibits an OCV of 1.44 V, and three batteries in series power a demo traffic signal. To underscore the efficiency of hydroxide ion transport through the complex multifunctional backbone of the polymer, we calculated the diffusion coefficient for OH- (Exp: 2.9 x 10(-5) cm(2) s(-1); Comp. 5.2 x 10(-6) cm(2) s(-1)) using electrochemical methods and MD simulations. Climbing-edge NEB calculations reveal a large energy barrier of 2.11 eV for Zn2+ to penetrate the polymer and identify hydroxide ions within the polymer, suggesting no undesirable Zn2+ crossover. Our findings assert the readily accessible C-C-linked cationic polymer{\textquoteright}s capacity as a solid-state electrolyte for ZABs and any anion-conducting membrane.

}, issn = {2055-6756}, doi = {10.1039/d2nh00455k}, author = {Rase, Deepak and Illathvalappil, Rajith and Singh, Himan Dev and Shekhar, Pragalbh and Leo, Liya S. and Chakraborty, Debanjan and Haldar, Sattwick and Shelke, Ankita and Ajithkumar, Thalasseril G. and Vaidhyanathan, Ramanathan} } @article {48735, title = {Made to measure squaramide COF cathode for zinc dual-ion battery with enriched storage via redox electrolyte}, journal = {Advanced Energy Materials}, volume = {13}, year = {2023}, month = {SEP}, type = {Article}, abstract = {

Aqueous rechargeable batteries are promising grid-scale energy storage devices because of their affordability, operational safety, and environmental benignity. Among these, Zn-ion batteries (ZIBs) have unfolded new horizons. Designing superior cathodes for ZIBs is crucial. Covalent organic frameworks (COFs) can be made redox active with a high storage surface. Here, for the first time, a chelating COF with redox-active ZnI2 in a ZnSO4(aq) electrolyte is combined. Including iodide harvests an approximately threefold enhancement in capacity from 208 to 690 mAh g(-1) at 1.5 A g(-1), the highest among all the COF-derived ZIBs. Remarkably, a charge-discharge curve at 1.3 V exhibits very limited dropout voltage and super-flat platform, with a remarkable capacity of 600 mAh g(-1) at 5 A g(-1) stable up to 6000 cycles, confirming that the polyiodide generation and storage are sustainable. The COF{\textquoteright}s dual-ion storage (Zn2+ and polyidode) delivers a ZIB with the highest energy density. Spectro-electrochemical measurements coupled with X-ray photoelectron spectroscopy unambiguously unveil the existence of multiple polyiodide species, with I-3(-) and IO3- ions as the prominent species. The latter gets reduced at the COF electrode under an applied potential, leaving I-3(-) as the major species stored on the COF. The prospect of COF-polyiodide((aq)) is a windfall for metal-ion batteries.

}, keywords = {covalent organic frameworks, flexible batteries, polyiodide, redox electrolytes, Zn ion batteries}, issn = {1614-6832}, doi = {10.1002/aenm.202301049}, author = {Kushwaha, Rinku and Jain, Chitvan and Shekhar, Pragalbh and Rase, Deepak and Illathvalappil, Rajith and Mekan, Deep and Camellus, Augastus and Vinod, Chathakudath Prabhakaran and Vaidhyanathan, Ramanathan} } @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} }