The Roles of Surface Hydrogen and Hydroxyl in Alkaline Hydrogen Oxidation on Ni‐Based Electrocatalysts

Abstract One important target for anion exchange membrane fuel cells (AEMFCs) is to enable the application of anode non‐precious metal hydrogen oxidation reaction (HOR) catalyst. Nickel presents a promising candidate for alkaline HOR; yet, its practical application is hampered by the intrinsically sluggish activity and poor stability. Herein, a series of Ni‐based metals (Ni 5 Mo, Ni 25 Co, Ni 14 W and Ni) are electrodeposited as model catalysts to systematically explore the alkaline HOR by considering the role of adsorbed hydroxyl (OH ad ). Spectroscopic studies together with density functional theory calculations shed light on the beneficial effect of transition metal M (M=Mo, Co, W) alloying/doping on HOR by introducing the charge transfer from M to Ni and down shifting Ni 3 d band center. The HOR specific activities on Ni‐based catalysts reveal a volcano‐type relationship with the hydrogen binding energy (HBE). The strongly adsorbed OH ad is proven to induce deactivation for Ni active sites, and the deactivation potential is OH ad binding energy (OHBE) dependent. This study adds new insight into the HOR mechanism and stability of Ni‐based electrocatalysts, providing a new avenue for the rational design of highly efficient and robust alkaline HOR catalysts.