Highly efficient H2 generation over Cu2Se decorated CdS0.95Se0.05 nanowires by photocatalytic water reduction

The development of efficient co-catalysts for promoting solar-driven water splitting to hydrogen (H) energy conversion is of increasing importance but still a challenging scheme. In the present work, a noble-metal-free copper selenide (CuSe) is primarily evaluated the possibility of functioning as a co-catalyst for enhancing photocatalytic H evolution activity by virtue of density functional theory (DFT) calculations. Then, the photocatalysts CdSSe nanowires (NWs) decorated with CuSe nanoparticles (NPs) as co-catalyst are designed and successfully fabricated via a hydrothermal method. Under visible light (λ ≥ 400 nm) illumination, the as-prepared CuSe/CdSSe nanocomposites loading with 20 mol% of CuSe NPs exhibits the highest photocatalytic activity with an H generation rate of 570.7 μmol·h and a corresponding apparent quantum efficiency (AQE) of 31.26%, which is about 7.1 and 27.4 times greater than that of pristine CdSSe and CdS NWs, respectively. Theoretical calculations and experimental measurements demonstrate that the excellent activity of the hybrid catalysts is ascribed to the formation of Ohmic-type heterojunctions between CdSSe semiconductor and semi-metallic CuSe, which can not only facilitate the charge carriers separation and transportation but also improve the surface H-evolution kinetics.