@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 {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 {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 {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} }