Photocatalytic H2 Evolution on CdS Loaded with WS2 as Cocatalyst under Visible Light Irradiation

WS2/CdS photocatalysts with different amounts of WS2 cocatalyst are prepared by loading WS2 on CdS with an impregnation–sulfidation approach. The transformation process of the tungsten species loaded on CdS together with the junctions formed between WS2 and CdS are clearly demonstrated with X-ray photoelectron spectroscopy and transmission electron microscopy. Photocatalytic H2 production on WS2/CdS catalysts under visible light (λ > 420 nm) shows that WS2 cocatalyst plays a crucial role in H2 production. Under optimum conditions, the rate of H2 evolution can be increased by up to 28 times when CdS was loaded with only 1.0 wt % WS2, and WS2 demonstrates a catalytic performance comparable or even superior to those of noble metals. Photocatalytic reaction results and electrochemical measurements indicate that the significantly enhanced H2 evolution of WS2/CdS catalyst mainly owns to the junctions formed between WS2 and CdS and the excellent performance of WS2 as a cocatalyst in catalyzing H2 evolution.