Co-Modification with Cost-Effective Nickel Oxides and Nickel Sulfides on CuInS2 Nanosheets Photocathode for Enhanced Photoelectrochemical Performance

Developing cost-effective and robust cocatalysts to substitute conventional Pt-group noble metals may be a great challenging stratagem for effective photoelectrochemical (PEC) water splitting. It is certified that the designed low-cost nickel oxides (NiO) and nickel sulfides (NiS) to co-modify a CuInS2 photocathode presents good light absorption, outstanding photocurrent density, and considerable positive onset potential, ascribing to the superior catalytic behavior of NiS for the hydrogen evolution reaction as well as the introduction of the NiO hole transfer layer (HTL). The resulting NiS/CuInS2/NiO photocathode exhibits a dramatically enhanced photocurrent density of −2.23 mA/cm2 at −0.6 V vs RHE, 175% higher than that of the CuInS2 photocathode alone. Our work can provide a reliable approach for low-cost cocatalyst design to replace noble metals in practical applications toward sunlight-driven PEC water splitting.