Lattice Oxygen-Induced d-Band Shifting for Enhanced Hydrogen Oxidation Reaction on Nickel

The application of anion exchange membrane fuel cells is hampered by the development of highly efficient and earth-abundant anode hydrogen oxidation reaction (HOR) catalysts. Here, a series of nickel catalysts (denoted as Ni-X) with different lattice oxygen (LO) contents were synthesized by H2 reduction of nickel hydroxide at temperatures (X) ranging from 300 to 500 °C. The Ni-400 (LO/Ni = 0.41, NiO0.41) catalyst with an optimum LO content showed excellent HOR activity and stability, comparable to current Ni-based electrocatalysts. An X-ray photoemission spectroscopic study, combined with density functional theory calculations, suggested that introducing LO into Ni modified the metal d-band electronic structure and in turn the hydrogen binding energy, which played a major role in determining the HOR performance.