Hydrogen Oxidation Reaction on Pd‐Ni(OH)2 Composite Electrocatalysts in an Alkaline Electrolyte

Exploring the mechanism of hydrogen oxidation reaction (HOR) in alkaline media is essential for the development of alkaline polymer electrolyte fuel cells (APEFCs). In this work, a series of Pd−Ni(OH)2 composites with different Pd/Ni atomic ratios (Pd : Ni=1:0 (without Ni addition), 7 : 1, 5 : 1, 3 : 1, 1 : 1) have been synthesized via wet chemical reduction method, and their corresponding HOR activities have been systematically evaluated with rotating disk electrode (RDE) technique. A good linear relationship between the HOR activities (described as the mass activity and exchange current density) and the surface oxophilicities (assessed by the oxidation current at 0.3 V vs. RHE in CO stripping voltammetry) is observed, indicating a bifunctional mechanism for HOR. The present study offers a direction for further improving the activity of Pd‐based HOR electrocatalyst. An in‐depth understanding of the hydrogen oxidation reaction (HOR) mechanism in alkaline medium is of great significance for the commercial application of alkaline polymer electrolyte fuel cells (APEFCs). The HOR activities on Pd/C and Pd−Ni(OH)2/C composites with different Pd/Ni atomic ratios display a positive linear correlation with the catalytic surface oxophilicities, which strongly suggests a bifunctional mechanism for alkaline HOR.