Metal/CeO₂−ₓ with regulated heterointerface, interfacial oxygen vacancy and electronic structure for highly efficient hydrogen evolution reaction

Abstract

The high activity of the metal/oxide heterostructures towards hydrogen evolution reaction (HER) is generally attributed to the metal-oxide synergy. A comprehensive study is thus needed to definitely unveil the origin of the catalytic activity of the metal/oxide heterostructures. Herein, Ni/CeO₂₋ₓ, Co/CeO₂₋ₓ and NiCo/CeO₂₋ₓ heterostructures are in-situ synthesized by hydrogenation. Both experimental and computational results validate that the presence of Ni favors the formation of interfacial oxygen vacancies, which facilitate the adsorption of H₂O molecules for HER. Theoretical calculations further show that the desorption of OH* is the rate-determining step, and that the desorption barrier of OH* on the NiCo/CeO₂₋ₓ is the lowest because of the NiCo alloying induced regulation in electronic structure. Additionally, the NiCo-CeO₂₋ₓ heterointerface greatly promotes the charge accumulation, leading to the low onset potential. Therefore, the NiCo/CeO₂₋ₓ presents the highest intrinsic activity with a small overpotential of 30 mV at 10 mA cm⁻² in 1.0M KOH.