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 (H2) energy conversion is of increasing importance but still a challenging scheme. In the present work, a noble-metal-free copper selenide (Cu2Se) is primarily evaluated the possibility of functioning as a co-catalyst for enhancing photocatalytic H2 evolution activity by virtue of density functional theory (DFT) calculations. Then, the photocatalysts CdS0.95Se0.05 nanowires (NWs) decorated with Cu2Se nanoparticles (NPs) as co-catalyst are designed and successfully fabricated via a hydrothermal method. Under visible light (λ ≥ 400 nm) illumination, the as-prepared Cu2Se/CdS0.95Se0.05 nanocomposites loading with 20 mol% of Cu2Se NPs exhibits the highest photocatalytic activity with an H2 generation rate of 570.7 μmol·h−1 and a corresponding apparent quantum efficiency (AQE) of 31.26%, which is about 7.1 and 27.4 times greater than that of pristine CdS0.95Se0.05 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 CdS0.95Se0.05 semiconductor and semi-metallic Cu2Se, which can not only facilitate the charge carriers separation and transportation but also improve the surface H2-evolution kinetics.