Oxygen-vacancy-rich MoO₂ supported nickel as electrocatalysts to promote alkaline hydrogen evolution and oxidation reactions

Hydrogen energy is the most suitable solution for long-term, large-scale energy storage, and the design of efficient, economical, and stable electrocatalysts for hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) is of great significance for its commercial development. Herein, Ni nanocluster supported on oxygen-vacancy-rich MoO2 (Ni/MoO2_x) is designed which contains a large number of oxygen vacancies and Ni-O-Mo bonds. According to X-ray photoelectron spectroscopy, the formation of oxygen vacancies and Ni-O-Mo bonds facilitates the transfer of electrons from Ni to O. The prepared Ni/MoO2_x@NF shows excellent hydrogen electrocatalytic activity, which is proved by a Tafel slope of only 26 mV dec_ 1 for HER and an exchange current density of 3.64 mA cm_ 2 for HOR. Theoretical calculations showed optimized free energy of hydrogen adsorption and hydroxide adsorption on Ni/MoO2_x, which can explain the origin of the high activity of the catalyst. This work provides a feasible strategy for designing non-precious metal hydrogen electrocatalytic materials in energy storage.