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

The synergy between the heterointerface and interfacial oxygen vacancy, combined with the regulated electronic structure, leads to the outstanding catalytic performance of NiCo/CeO 2−x towards hydrogen evolution reaction. [Display omitted] • The Ni favors the formation of interfacial oxygen vacancies in the metal/CeO 2−x. • The introduction of Co regulates the electronic structure of the metal/CeO 2−x. • The interfacial oxygen vacancies enhance the water adsorption. • The NiCo/CeO 2−x shows the lowest desorption barrier of OH*. • The high activity is assigned to the regulated interfacial structure and electronic structure. 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/CeO 2−x , Co/CeO 2−x and NiCo/CeO 2−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 H 2 O 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/CeO 2−x is the lowest because of the NiCo alloying induced regulation in electronic structure. Additionally, the NiCo-CeO 2−x heterointerface greatly promotes the charge accumulation, leading to the low onset potential. Therefore, the NiCo/CeO 2−x presents the highest intrinsic activity with a small overpotential of 30 mV at 10 mA cm−2 in 1.0 M KOH. [ABSTRACT FROM AUTHOR]