Hydrogen Evolution Reaction on AuNi Surface Alloy Formed on Single Crystal Au Electrodes

Abstract

AbstractThe hydrogen evolution reaction (HER) on Au with high chemical stability is activated by alloying it with Ni. We evaluated the HER activity of the AuNi surface alloy prepared at different alloying temperatures on single‐crystal Au electrodes in 0.05 M H2SO4. The potential cycle, including the region of Ni oxidative dissolution, further enhanced the HER activity by dealloying Ni, and the activity depended on the surface structure of the Au substrate in the following order: AuNi/Au(100)<AuNi/Au(111)<AuNi/Au(110). The surface structure and atomic composition were investigated using X‐ray photoelectron spectroscopy and surface X‐ray diffraction. Surface structural analysis revealed that the dissolution of Ni from the AuNi surface‐alloy layer resulted in a decrease in the atomic occupancy of the topmost surface layer. Ni dealloying creates low‐coordination Au sites on the AuNi surface alloy, which activates the HER.