Synergistic effect of electronic modulation and oxygen vacancy in Cu2O@CuNiMo heterostructure for accelerating alkaline electrocatalytic hydrogen evolution reaction

Electrochemical water splitting is an attractive chemical method for hydrogen generation with cleanliness and zero pollution. However, the reported catalysts are still unsatisfactory due to low electron transport efficiency and poor water splitting capacity. Herein, a high-performance oxygen vacancy-rich Cu2O-based heterostructure (Cu2O@CuNiMo) was constructed for solving these problems. The results of X-ray photoelectron spectroscopy and Raman suggested that there was strong electron transfer between CuNiMo and Cu2O, which could optimize the electronic structure. Electron paramagnetic resonance proved that there were abundant oxygen vacancies (OVS) on the surface of the Cu2O, which generated a mass of adsorbed hydrogen (Hads) by accelerating water splitting in an alkaline solution. Therefore, the Cu2O@CuNiMo electrocatalyst exhibits outstanding hydrogen evolution reaction (HER) performance with an ultra-low overpotential of 49 mV at a current density of 10 mA cm-2 in 1.0 M KOH electrolyte, outperforming many other previously reported transition metal-based catalysts. Moreover, Cu2O@CuNiMo exhibits exceptional durability for a 24-h long-term test at a current density of 200 mA cm-2. This work provides a promising method to design highly active HER electrocatalysts via the dual regulation strategy of oxygen vacancy engineering and electronic behavior.