Promoting effect of nickel-chromium hydroxide on nickel phosphide nanosheets for efficient hydrogen production coupled with sulfion degradation

Abstract

Electrochemical hydrogen production represents a sustainable approach for hydrogen generation. However, its large-scale practical application is largely limited by the sluggish oxygen evolution reaction (OER). In this study, the thermodynamically favorable sulfion oxidation reaction (SOR) is employed to replace slow OER and nickel phosphide/nickel-chromium hydroxide (Ni2P/NiCr(OH)2) nanosheets are constructed to achieve low-energy hydrogen production. Benefiting from the interfacial water structure reorganization and electronic structure optimization caused by NiCr(OH)2) introduction, and uniform nanosheet morphology, Ni2P/NiCr(OH)2 can achieve a current density of 10 mA cm-2 at low overpotentials for both hydrogen evolution reaction and SOR. The assembled hybrid water electrolyzer requires small voltages of 0.513 and 0.698 V to reach 10 and 100 mA cm-2, significantly lower than those of conventional water electrolysis. Moreover, Ni2P/NiCr(OH)2 exhibits excellent stability for 800 h at 200 mA cm-2 and realizes the conversion of sulfion into valuable elemental sulfur. This work presents a promising strategy for achieving energy-efficient hydrogen generation and resource utilization of sulfide-containing pollutants.