@article { ISI:000237003000008, title = {Role of dopant ions in electrocatalytic oxidation of methanol using conducting polypyrrole electrodes}, journal = {Journal of Power Sources}, volume = {155}, number = {2}, year = {2006}, month = {APR}, pages = {157-160}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Conducting polypyrrole electrodes obtained by electro-polymerization of pyrrole on vacuum metallized glass substrates are modified by doping with a range of metal halides as dopant ions having different electronegativity. Electro-oxidation of methanol using these electrodes is studied by means of cyclic voltammetry in 0.1 M HCiO(4) as supporting electrolyte. It is found that the electronegativity of the dopant ion plays a very important role in the electrocatalytic activity. Polypyrrole doped with zirconium chloride gives the highest anodic current of 10 mA cm(-2) at the oxidation potential of methanol. The results are explained on the basis of the charge-transfer efficiency at the electrode I electrolyte interface, which is associated with the acceptor state created by the dopant in the semi-conducting polymer. (c) 2005 Published by Elsevier B.V.

}, keywords = {conducting polymers, electrocatalysis, fuel cells, Methanol oxidation, polypyrrole}, issn = {0378-7753}, doi = {10.1016/j.jpowsour.2005.03.234}, author = {Radhakrishnan, S. and Adhikari, Arindam} } @article { ISI:000287058200011, title = {Dopant induced effect on electrocatalytic reduction of nitrobenzene using conducting polypyrrole thin film electrodes}, journal = {Journal of Applied Polymer Science}, volume = {120}, number = {2}, year = {2011}, month = {APR}, pages = {719-724}, publisher = {WILEY-BLACKWELL}, address = {COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA}, abstract = {

Conducting polypyrrole electrodes were prepared by electrochemical polymerization of pyrrole on vacuum-metallized glass substrates. These electrodes were modified by doping with a range of metal halides as dopant ions having different electronegativity. Electrochemical reduction of nitrobenzene using these electrodes was studied by means of cyclic voltammetry technique in acetonitrile medium containing aqueous HClO(4) (0.1M) as supporting electrolyte. It was found that the electronegativity of the dopant ion played a very important role in the electrocatalytic activity. Polypyrrole doped with nickel chloride gave the highest anodic current at the reduction potential of nitrobenzene. The results were explained on the basis of charge transfer efficiency at the electrode-electrolyte interface, which was associated with the acceptor state created by the dopant in the semi-conducting polymer. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 719-724, 2011

}, keywords = {charge transfer, conducting polymer, Doping, electrocatalysis, nitrobenzene, polypyrrole, reduction}, issn = {0021-8995}, doi = {10.1002/app.31417}, author = {Adhikari, Arindam and Radhakrishnan, S.} } @article { ISI:000315172400021, title = {Significant enhancement of formic acid oxidation using rhodium nanostructures}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {12}, number = {12}, year = {2012}, month = {DEC}, pages = {8994-8998}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {

The electrocatalytic activity of as-synthesized shape selective Rh nanostructures has been demonstrated using cyclic voltammetry, revealing unique shape-dependant performance towards HCOOH oxidation. interestingly, the enhancement factor (R) for different shapes of Rh with respect to that of commercial Rh towards formic acid oxidation ranges up to 20,000\% for cubes as compared to 17,500\% for pyramids and 11,000\% for hexagons respectively. Mechanistic pathway for comparatively better sensitivity of cubes as compared to other shapes has been correlated with the results of X-ray diffraction.

}, keywords = {electrocatalysis, Formic Acid Oxidation, Preferential Growth, Rhodium Nanostructures}, issn = {1533-4880}, doi = {10.1166/jnn.2012.6735}, author = {Balan, Beena K. and Sathe, Bhaskar R.} } @article { ISI:000332144600065, title = {Facile single-step synthesis of nitrogen-doped reduced graphene oxide-Mn3O4 hybrid functional material for the electrocatalytic reduction of oxygen}, journal = {ACS Applied Materials \& Interfaces}, volume = {6}, number = {4}, year = {2014}, month = {FEB}, pages = {2692-2699}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Development of efficient electrocatalyst based on non-precious metal that favors the four-electron pathway for the reduction of oxygen in alkaline fuel cell is a challenging task. Herein, we demonstrate a new facile route for the synthesis of hybrid functional electrocatalyst based on nitrogen-doped reduced graphene oxide (N-rGO) and Mn3O4 with pronounced electrocatalytic activity towards oxygen reduction reaction (ORR) in alkaline solution. The synthesis involves one-step in situ reduction of both graphene oxide (GO) and Mn(VII), growth of Mn3O4 nanocrystals and nitrogen doping onto the carbon framework using a single reducing agent, hydrazine. The X-ray photoelectron (XPS), Raman and FTIR spectral, and X-ray diffraction measurements confirm the reduction of GO and growth of nanosized Mn3O4. The XPS profile reveals that N-rGO has pyridinic (40\%), pyrrolic (53\%), and pyridine N oxide (7\%) types of nitrogen. The Mn3O4 nanoparticles are single crystalline and randomly distributed over the wrinkled N-rGO sheets. The hybrid material has excellent ORR activity and it favors the 4-electron pathway for the reduction of oxygen. The electrocatalytic performance of the hybrid catalyst is superior to the N-rGO, free Mn3O4 and their physical mixture. The hybrid material shows an onset potential of -0.075 V, which is 60-225 mV less negative than that of the other catalyst tested. It has excellent methanol tolerance and high durability. The catalytic current density achieved with the hybrid material at 0.1 mg cm(-2) is almost equivalent to that of the commercial Pt/C (10\%). The synergistic effect of N-rGO and Mn3O4 enhances the overall performance of the hybrid catalyst. The nitrogen in N-rGO is considered to be at the interface to bridge the rGO framework and Mn3O4 nanoparticles and facilitates the electron transfer.

}, keywords = {electrocatalysis, hybrid material, Mn3O4, nitrogen-doped graphene, oxygen reduction, synergistic effect}, issn = {1944-8244}, doi = {10.1021/am405213z}, author = {Bag, Sourav and Roy, Kanak and Gopinath, Chinnakonda S. and Raj, C. Retna} } @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 {47729, title = {Structure-tailored non-noble metal-based ternary chalcogenide nanocrystals for pt-like electrocatalytic hydrogen production}, journal = {ChemSusChem}, volume = {14}, year = {2021}, month = {AUG }, pages = {3074-3083}, type = {Article}, abstract = {A facile microwave-assisted strategy was employed to synthesize Ni3Bi2S2 nanocrystals. Variation in the synthesis conditions tuned the composition of monoclinic and orthorhombic phases of Ni3Bi2S2. The electrochemical hydrogen evolution activity of the catalyst with highest percentage of monoclinic phase demonstrated a negligible onset potential of only 24 mV close to that of state-of-the-art Pt/C with an overpotential as low as 88 mV. Density functional theory calculations predicted the monoclinic phase exhibit the lowest adsorption free energy corresponding to hydrogen adsorption (Delta GadsH*) and, therefore, the highest hydrogen evolution activity amongst the considered phases. The quasi-2D structure of monoclinic phase facilitated an increased charge-transfer between Ni and Bi, favoring the downward shift of the d-band center to enhance the catalytic activity.}, keywords = {charge transfer, electrocatalysis, hydrogen evolution reaction, Nanomaterials, ternary chalcogenides}, issn = {1864-5631}, doi = {10.1002/cssc.202100967}, author = {Sarkar, Shreya and Rawat, Abhishek and Das, Tisita and Gaboardi, Mattia and Chakraborty, Sudip and Vinod, C. P. and Peter, Sebastian C.} } @article {47105, title = {Unveiling the roles of lattice strain and descriptor species on pt-like oxygen reduction activity in Pd-Bi catalysts}, journal = {ACS Catalysis}, volume = {11}, year = {2021}, month = {JAN}, pages = {800-808}, type = {Article}, abstract = {

A facile non-template-assisted mechanical ball milling technique was employed to generate a PdBi alloy catalyst. The induced lattice strain upon the milling time caused a shift of the d-band center, thereby enhancing the oxygen reduction reaction (ORR) catalytic activity. Additionally, the Pd-O reduction potential and adsorbed OH coverage used as descriptors stipulated the cause of the enhanced ORR activity upon the increased milling interval. Redox properties of surface Pd are directly correlated with a positive shift in the Pd-O reduction potential and OH surface coverage. Hence, by deconvoluting the lattice strain and the role of the descriptor species we achieved a catalyst system with a specific activity 5.4X higher than that of commercial Pt/C, as well as an improved durability. The experimental observation is well-corroborated by a theoretical simulation done by inducing strain to the system externally.

}, keywords = {charge-transfer, electrocatalysis, fuel cell, Lattice strain, oxygen reduction, Pt-like activity}, issn = {2155-5435}, doi = {10.1021/acscatal.0c03415}, author = {Sarkar, Shreya and Ramarao, S. D. and Das, Tisita and Das, Risov and Vinod, C. P. and Chakraborty, Sudip and Peter, Sebastian C.} } @article {48374, title = {Concurrent polyvalent interaction and electrocatalysis to improve lithium-sulfur battery performance}, journal = {Batteries \& Supercaps}, volume = {5}, year = {2022}, month = {FEB}, type = {Article}, abstract = {

Batteries with improved efficiency are desired. Li-S batteries are attractive due to their high specific capacity and energy density. However, sluggish sulfur redox reaction and polysulfide dissolution are significant challenges in Li-S batteries. In this work, we report graphene with doped layer to electrocatalyze the sluggish sulfur redox reaction. The doped layer comprises heteroatoms such as either N or N and S. The doped layer also comprises cations of Ni. We have chosen a {\textquoteleft}{\textquoteleft}doped layer on graphene{\textquoteright}{\textquoteright} over {\textquoteleft}{\textquoteleft}doped graphene{\textquoteright}{\textquoteright} to avoid defects in the basal plane of graphene. We found the doped layer comprising graphene (DLC-G) to electrocatalyze the polysulfide redox reaction. However, the interaction between the doped layer and polysulfide is still weak, hence the dissolution is not suppressed. To circumvent the polysulfide dissolution, graphene with cationic layer was prepared. We found that cations in the layer electrostatically attract the polysulfides due to the polyvalent interaction. Thus, the dissolution is suppressed. While using this material in the Li-S batteries, the specific capacity, energy density and power density were found to be 1345 mAh g(-1), 782 Wh kg(-1) and 4437 W kg(-1), respectively.

}, keywords = {electrocatalysis, graphene, lithium-sulfur battery, mechanical exfoliation, polyvalent interaction}, doi = {10.1002/batt.202100229}, author = {Kumar, Subramani and Krishnamoorthy, Kothandam} } @article {48779, title = {Alloying with Mn enhances the activity and durability of the CoPt catalyst toward the methanol oxidation reaction}, journal = {ACS Applied Materials \& Interfaces}, volume = {15}, year = {2023}, month = {MAY}, pages = {26554-26562}, type = {Article}, abstract = {

To improve the catalytic performance and durability ofPt catalystsused for the methanol oxidation reaction (MOR) in direct methanolfuel cells (DMFCs), alloying of Pt with other transition metals suchas Ru, Co, Ni, and Fe is considered an effective approach. Despitethe significant progress made in the preparation of bimetallic alloysand their utilization for MOR, improving the activity and durabilityof the catalysts to make them commercially viable remains a stiffchallenge. In this work, trimetallic Pt100-x (MnCo)( x ) (16 \< x \< 41) catalysts were successfully synthesized via borohydridereduction followed by hydrothermal treatment at 150 \& DEG;C. The electrocatalyticperformance of the synthesized trimetallic Pt100-x (MnCo)( x ) (16 \< x \< 41) catalysts toward MOR was studied using cyclicvoltammetry and chronoamperometry. The results affirm that all Pt100-x (MnCo)( x ) (16 \< x \< 41) alloys have superior MOR activityand durability as compared to bimetallic PtCo alloys and commerciallyavailable Pt/C (comm. Pt/C) catalysts. Among all the compositionsstudied, the Pt60Mn1.7Co38.3/C catalystexhibited superior mass activity (1.3 and 1.9 times higher than thoseof Pt81Co19/C and comm. Pt/C, respectively)toward MOR. Furthermore, all the newly synthesized Pt100-x (MnCo)( x )/C (16 \< x \< 41) catalysts showed better CO tolerance when comparedwith comm. Pt/C. This improved performance of the Pt100-x (MnCo)( x )/C (16 \< x \< 41) catalyst can be attributed to the synergisticeffect of Co and Mn on the Pt lattice.

}, keywords = {CO tolerance, direct methanol fuel cells, electrocatalysis, methanol oxidation reaction(MOR), trimetallic alloy catalysts}, issn = {1944-8244}, doi = {10.1021/acsami.3c01140}, author = {Deshpande, Pooja and Prasad, Bhagavatula L. V.} } @article {48721, title = {Can metal cations electrocatalyze sulfur redox reaction and suppress polysulfide shuttle?}, journal = {Batteries \& Supercaps}, volume = {6}, year = {2023}, month = {SEP}, type = {Article}, abstract = {

In lithium-sulfur (Li-S) batteries, sulfur undergoes various changes. It switches between cyclic structure and linear structure. The charge on the sulfur varies between a neutral state and a negative charge-bearing state. Due to these changes, the sulfur/polysulfide dissolves in the battery electrolyte. Furthermore, the kinetics of the sulfur redox reaction is sluggish. Therefore, a material that can suppress sulfur/polysulfide dissolution and electrocatalyze sulfur redox reaction is needed. We hypothesize that the polysulfide dissolution can be suppressed if the host exhibits polyvalent electrostatic attraction. Polysulfide is a negative charge-bearing molecule; hence the host must comprise multiple positive charges. Nickel cations with other heteroatoms have been explored as a host in Li-S batteries. The heteroatoms impart additional interactions. The easier way to circumvent the effect of heteroatoms is the addition of metal salts. However, metal salts can either exhibit monovalent or divalent attraction with polysulfides. Those interactions are weak and we must have polyvalent interaction. Towards this objective, we have designed and synthesized a material that comprises multiple divalent cations that is also devoid of heteroatoms. The Li-S batteries fabricated using the metal cation immobilized graphene showed a maximum specific capacity of 1022 mAh/g at 0.1 C rate. Among the metal cations, nickel cations showed better performance than cobalt cations. Thus, we demonstrate that metal cations immobilized on Graphene can efficiently electrocatalyze the sluggish sulfur redox reaction and suppress the polysulfide dissolution.

}, keywords = {electrocatalysis, graphene, lithium-sulfur batteries, metal cations, polysulfides}, doi = {10.1002/batt.202300136}, author = {Kumar, Subramani and Swain, Gitanjali and Krishnamoorthy, Kothandam} } @article {48809, title = {Theory-directed designing of an intrinsic-activity-modulated metal-doped copper oxide electrode for nitrate to ammonia synthesis}, journal = {ACS Applied Energy Materials}, volume = {6}, year = {2023}, month = {MAY}, pages = {6111-6119}, type = {Article}, abstract = {

Synthesis of ammonia via electrochemical reduction ofnitrate isone of the most sustainable routes both for environmental protectionas well as energy saving initiatives. However, this process is limitedto the development of high-performance free-standing catalytic electrodeswith improved selectivity and Faradaic efficiency. Herein, we reporttheory-guided designing and fabrication of free-standing non-noblemetal (Mn, Fe, and Co)-doped copper oxide (CuO) electrodes by usinga simple and scalable electrode preparation method. The density functionaltheory (DFT)-based calculations show that the doped-Co sites in theCu surface facilitate the generation and supply of H+ tothe adsorbed NO3 (-) during the reductionprocess; as a result, the Co-CuO catalyst displays higher selectivitytoward nitrate reduction. The Co-doped Cu electrode (Co-CuO)delivers a higher NH3 yield (5492 mu g cm(-2)) at a reduction potential of -0.91 V vs RHE while maintaininga Faradaic efficiency of \>95\%. The alloying of Co to the coppermetalnot only facilitates the proton donation to the adsorbed reactant(NO3 (-)) but also tunes the Cu d-center,resulting in the active site modulation responsible for the activationof catalysts.

}, keywords = {Active sites, ammonia synthesis, electrocatalysis, Faradaic efficiency, High selectivity, metal-doped electrode}, issn = {2574-0962}, doi = {10.1021/acsaem.3c00617}, author = {Tyagi, Nitin Kumar and Mahapatra, Bikash K. and Ghimire, Suvash and Manna, Narugopal and Kumar, Deepak and Kumar, Vijay and Mukhopadhyay, Kausik and Singh, Santosh K.} }