Solar hydrogen evolution using a CuGaS2 photocathode improved by incorporating reduced graphene oxide

Abstract

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 H₂ indicated that the enhanced cathodic photocurrent was used for water reduction to H₂. Upon combining the developed RGO–CuGaS₂ composite photocathode with a BiVO₄ photoanode loaded with a CoO_x cocatalyst, photocurrent and the corresponding H₂ evolution were successfully observed without applying an external bias between both photoelectrodes under simulated sunlight irradiation.