Pd‐Decorated Tungsten as Pt‐Free Bimetallic Catalysts for Hydrogen Oxidation Reaction in Alkaline Electrolyte

Arulrajan, Antony C.; Subramanian, Palaniappan; Singh, Ramesh Kumar; Schechter, Alex

doi:10.1002/ijch.201900140

Cited by 9 publications

(6 citation statements)

References 35 publications

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“…Ni/NiO-decorated fibers' HOR curves show negligible current towards HOR reflecting the role of Pd in Pd-grown@Ni/NiO-decorated fibers. The HOR current at 0.10 V is comparable to those recorded for Pd–W–C, 37 Pd, 38 Pd–CeO 2 . 9 Pd-grown@Ni/NiO-decorated fibers were further analyzed to investigate the mass-transport behavior by varying the electrode's rotation speed ( Fig.…”

Section: Resultssupporting

confidence: 75%

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confidence: 75%

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“…Similar observations were reported previously where the Volmer step is the ratedetermining step (rds). 44,45 Hence, the HOR mechanism of the electrocatalysts followed the Tafel−Volmer mechanism. CA (Figure 7F) of the electrocatalysts revealed their stability during HOR at steady-state conditions.…”

Section: Resultsmentioning

confidence: 99%

CeO₂ Modulates the Electronic States of a Palladium Onion-Like Carbon Interface into a Highly Active and Durable Electrocatalyst for Hydrogen Oxidation in Anion-Exchange-Membrane Fuel Cells

et al. 2022

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This study reports the preparation, characterization, and electrocatalytic properties of palladium-based catalysts containing ceria (CeO 2 ) on carbon black (CB) and onion-like carbon (OLC) supports. The electrocatalysts (Pd− CeO 2 /CB and Pd−CeO 2 /OLC) exhibit a large specific surface area, pore volume, and small particle size, as well as enhanced interfacial interaction and synergy among Pd, CeO 2 , and OLC in Pd−CeO 2 /OLC that are valuable for improved electrocatalysis. The presence of CeO 2 in Pd−CeO 2 /OLC induces ca. 7% defects and modifies the electronic structure of the Pd/OLC interface, significantly improving the electrical conductivity due to enhanced charge redistribution, corroborated by density functional theory (DFT) calculations. Pd−CeO 2 /OLC displays the lowest adsorption energies (H*, OH*, and OOH*) among the series. For the hydrogen oxidation reaction (HOR), Pd−CeO 2 /OLC delivers significantly enhanced HOR (mass-specific) activities of 4.2 (8.1), 13.2 (29.6), and 15 (78.5) times more than Pd−CeO 2 /CB, Pd/OLC, and Pd/CB, respectively, with the best diffusion coefficient (D) and heterogeneous rate constant (k). Pd−CeO 2 /OLC also displays less degradation during accelerated durability testing. In an anion-exchange-membrane fuel cell (AEMFC) with H 2 fuel, Pd−CeO 2 /OLC achieved the highest peak power density of 1.0 W cm −2 at 3.0 A cm −2 as compared to Pd−CeO 2 /CB (0.9 W cm −2 at 2.2 A cm −2 ), Pd/OLC (0.6 W cm −2 at 1.7 A cm −2 ), and Pd/CB (0.05 W cm −2 at 0.1 A cm −2 ). These results indicate that Pd−CeO 2 /OLC promises to serve as a high-performing and durable anode material for AEMFCs.

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“…This work underlined the importance of phase control during the synthesis of HOR electrocatalysts. In addition to alloying, the Pd layer surface coating or decoration provides another strategy for optimizing Pd atomic utilization. − …”

Section: Hor Electrocatalysis In Alkaline Mediamentioning

confidence: 99%

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

et al. 2022

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Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition of the global energy landscape from fossil fuels to renewable energy. Here, we present a comprehensive review of the fundamentals of electrocatalysis in alkaline media and applications in alkaline-based energy technologies, particularly alkaline fuel cells and water electrolyzers. Anion exchange (alkaline) membrane fuel cells (AEMFCs) enable the use of nonprecious electrocatalysts for the sluggish oxygen reduction reaction (ORR), relative to proton exchange membrane fuel cells (PEMFCs), which require Pt-based electrocatalysts. However, the hydrogen oxidation reaction (HOR) kinetics is significantly slower in alkaline media than in acidic media. Understanding these phenomena requires applying theoretical and experimental methods to unravel molecularlevel thermodynamics and kinetics of hydrogen and oxygen electrocatalysis and, particularly, the proton-coupled electron transfer (PCET) process that takes place in a proton-deficient alkaline media. Extensive electrochemical and spectroscopic studies, on single-crystal Pt and metal oxides, have contributed to the development of activity descriptors, as well as the identification of the nature of active sites, and the rate-determining steps of the HOR and ORR. Among these, the structure and reactivity of interfacial water serve as key potential and pH-dependent kinetic factors that are helping elucidate the origins of the HOR and ORR activity differences in acids and bases. Additionally, deliberately modulating and controlling catalyst−support interactions have provided valuable insights for enhancing catalyst accessibility and durability during operation. The design and synthesis of highly conductive and durable alkaline membranes/ionomers have enabled AEMFCs to reach initial performance metrics equal to or higher than those of PEMFCs. We emphasize the importance of using membrane electrode assemblies (MEAs) to integrate the often separately pursued/optimized electrocatalyst/support and membranes/ionomer components. Operando/in situ methods, at multiscales, and ab initio simulations provide a mechanistic understanding of electron, ion, and mass transport at catalyst/ionomer/membrane interfaces and the necessary guidance to achieve fuel cell operation in air over thousands of hours. We hope that this Review will serve as a roadmap for advancing the scientific understanding of the fundamental factors governing electrochemical energy conversion in alkaline media with the ultimate goal of achieving ultralow Pt or precious-metal-free highperformance and durable alkaline fuel cells and related technologies.

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Pd‐Decorated Tungsten as Pt‐Free Bimetallic Catalysts for Hydrogen Oxidation Reaction in Alkaline Electrolyte

Cited by 9 publications

References 35 publications

Metal nanoparticles entrapped in metal matrices

Metal nanoparticles entrapped in metal matrices

CeO₂ Modulates the Electronic States of a Palladium Onion-Like Carbon Interface into a Highly Active and Durable Electrocatalyst for Hydrogen Oxidation in Anion-Exchange-Membrane Fuel Cells

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

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Pd‐Decorated Tungsten as Pt‐Free Bimetallic Catalysts for Hydrogen Oxidation Reaction in Alkaline Electrolyte

Cited by 9 publications

References 35 publications

Metal nanoparticles entrapped in metal matrices

Metal nanoparticles entrapped in metal matrices

CeO2 Modulates the Electronic States of a Palladium Onion-Like Carbon Interface into a Highly Active and Durable Electrocatalyst for Hydrogen Oxidation in Anion-Exchange-Membrane Fuel Cells

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

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CeO₂ Modulates the Electronic States of a Palladium Onion-Like Carbon Interface into a Highly Active and Durable Electrocatalyst for Hydrogen Oxidation in Anion-Exchange-Membrane Fuel Cells