Improved Hydrogen Oxidation Reaction Activity and Stability of Buried Metal-Oxide Electrocatalyst Interfaces

Abstract

Various bifunctional metal-oxide composites have recently been proposed as advanced hydrogen oxidation reaction (HOR) electrocatalysts for anion-exchange membrane fuel cells (AEMFCs). It is postulated that metal and oxide are active sites for the adsorption of hydrogen/proton and hydroxide ions, respectively. Of particular interest are the so-called buried interfaces. To investigate processes governing activity and stability at such interfaces, we prepare model Pd and Pt electrocatalysts which are fully covered by thin CeO x films. We investigate how oxide thickness influences HOR activity and dissolution stability of the electrocatalysts. It is found that materials behave very differently and that only Pd exhibits an enhanced HOR activity, while both oxide-protected metals are more stable toward dissolution. A 10-fold decrease in dissolution and 15-fold increase in HOR exchange current density are demonstrated for the optimized Pd/CeO x composites in comparison to pure Pd. We assess the mechanism of the electrocatalytic improvement as well as the role of the protective oxide films in such systems through advanced electrochemical and physical analysis. It is highlighted that a uniform, semipermeable oxide layer with a maximized electrocatalyst− oxide interface is crucial to form HOR catalysts with improved activity and stability.

Real‐time Monitoring Reveals Dissolution/Redeposition Mechanism in Copper Nanocatalysts during the Initial Stages of the CO2 Reduction Reaction

“…[9,10] Furthermore,t he development of strategies aimed at preventing dissolution, that is,the introduction of tailored interfaces with oxides or carbon, might help to overcome this issue. [49][50][51] Finally,future studies on the facet-dependence of the proposed mechanism are interesting and foreseen in the near future.…”

Real‐time Monitoring Reveals Dissolution/Redeposition Mechanism in Copper Nanocatalysts during the Initial Stages of the CO2 Reduction Reaction

“…However, the observed phenomena are expected to be less pronounced for larger NPs with lower surface‐to‐volume ratio, that are a more attractive choice for CO 2 RR because of suppressed activity for HER [9, 10] . Furthermore, the development of strategies aimed at preventing dissolution, that is, the introduction of tailored interfaces with oxides or carbon, might help to overcome this issue [49–51] . Finally, future studies on the facet‐dependence of the proposed mechanism are interesting and foreseen in the near future.…”

“…Forschungsartikel might help to overcome this issue. [49][50][51] Finally,future studies on the facet-dependence of the proposed mechanism are interesting and foreseen in the near future.…”

On the effect of anion exchange ionomer binders in bipolar electrode membrane interface water electrolysis

“…In contrast, the cathode side is kept in a PEM environment as the hydrogen evolution reaction (HER) requires only very low amounts of Pt catalyst and is favorable in acidic media. 20,21 The additionally created bipolar interface drives water dissociation into protons and hydroxide (Fig. 1b), which feed the respective electrode reactions.…”