▎ 摘　　要

The effectiveness of reduced graphene oxide (RGO) in water reduction on a CuGaS2 photocathode was demonstrated. Graphene oxide was photocatalytically reduced over CuGaS2 particles under visible light irradiation to give an RGO-CuGaS2 composite. The incorporated RGO dramatically enhanced the cathodic photocurrent of the CuGaS2 photoelectrode under visible light irradiation. Detection of evolved H-2 indicated that the enhanced cathodic photocurrent was used for water reduction to H-2. Upon combining the developed RGO-CuGaS2 composite photocathode with a BiVO4 photoanode loaded with a CoOx cocatalyst, photocurrent and the corresponding H-2 evolution were successfully observed without applying an external bias between both photoelectrodes under simulated sunlight irradiation.