Controlling photocatalytic properties of Eosin Y-sensitized hydrogen evolution reaction of Cu2−xSe nanoparticles through surface band bending

Abstract

Solar-driven water splitting for hydrogen (H2) production and energy conversion technologies have inspired impressive attention due to energy and environmental crises, but still challenges limit commercialization. To overcome these challenges, the visible-light-responsible noble-metal-free photocatalytic H2 production system is imperative. In this study, scalable synthesis of copper selenides which is one of promising semiconductor materials is developed and the Cu/Se compositions of the Cu2−xSe were readily controlled from copper (II) selenide (CuSe) to copper (I) selenide (Cu2Se). In addition, the synthesized copper selenides were applied to Eosin Y (EY)-sensitized photocatalytic H2 production, and Cu2Se exhibited the highest photocatalytic H2 production rate (1017.82 μmol∙g−1∙h−1) which was 21.17% higher than that of the commercial P25 (TiO2) under the same conditions. Through careful characterization and calculation, we investigated the band structures of the synthesized copper selenides with different Cu/Se molar ratio, and were able to propose the theory of enhanced surface H2-evolution kinetics based on downward band bending at equilibrium state in the EY-sensitized system.