Controlling photocatalytic properties of Eosin Y-sensitized hydrogen evolution reaction of Cu2_xSe nanoparticles through surface band bending

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 commer-cialization. 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 read-ily 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 exhib-ited the highest photocatalytic H2 production rate (1017.82 lmol center dot g_1 center dot h_1) which was 21.17% higher than that of the commercial P25 (TiO2) under the same conditions. Through careful characterization and cal-culation, 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.(c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.