Enhanced photocatalytic activity for hydrogen evolution from water by Zn0.5Cd0.5S/WS2 heterostructure

Zn_0.5Cd_0.5S/WS₂ nanocomposites with different amount of Zn_0.5Cd_0.5S solid solution deposited onto the surface of WS₂ were prepared by a one-step hydrothermal method with thioacetamide as sulfur source. Intimate heterojunctions between Zn_0.5Cd_0.5S and WS₂ were identified by TEM and HRTEM technologies in these materials. The chemical composition and valence of the elements were characterized by XPS experiments. The band energies were characterized by UV–vis diffusive reflectance spectroscopy (DRS). The photocatalytic properties of Zn_0.5Cd_0.5S/WS₂ nanocomposites for H₂ evolution from water in the presence of sacrificial reagents were tested. The highest rate of H₂ evolution achieved for these hybrid materials under visible-light irradiation (λ≥420 nm) is about 6 times higher than that of pristine Zn_0.5Cd_0.5S. The promoted catalytic activity of this hybrid material can be ascribed to the formation of the heterojunctions between Zn_0.5Cd_0.5S and WS₂, which enhanced the separation of the photogenerated hole-electron pairs.