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

Zn0.5Cd0.5S/WS2 nanocomposites with different amount of Zn0.5Cd0.5S solid solution deposited onto the surface of WS2 were prepared by a one-step hydrothermal method with thioacetamide as sulfur source. Intimate heterojunctions between Zn0.5Cd0.5S 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 Zn0.5Cd0.5S/WS2 nanocomposites for H-2 evolution from water in the presence of sacrificial reagents were tested. The highest rate of H-2 evolution achieved for these hybrid materials under visible-light irradiation (lambda >= 420 nm) is about 6 times higher than that of pristine Zn0.5Cd0.5S. The promoted catalytic activity of this hybrid material can be ascribed to the formation of the heterojunctions between Zn0.5Cd0.5S and WS2, which enhanced the separation of the photogenerated hole-electron pairs.