Enhancement of photocatalytic H2 evolution on Zn(0.8)Cd(0.2)S loaded with CuS as cocatalyst and its photogenerated charge transfer properties.

CuS/Zn(0.8)Cd(0.2)S composites have been successfully prepared by simple hydrothermal and cation exchange method. The Cu species loaded on Zn(0.8)Cd(0.2)S, together with the intimate contact formed between CuS and Zn(0.8)Cd(0.2)S, was clearly demonstrated with X-ray photoelectron spectroscopy and transmission electron microscopy. The optimized CuS/Zn(0.8)Cd(0.2)S photocatalyst has a high H2 evolution rate of 2792 μmol g(-1) h(-1) at CuS content of 3 wt% and the apparent quantum efficiency of 36.7% at 420 nm. The photophysical mechanism of the photocatalytic activity was investigated with the help of surface photovoltage spectroscopy (SPS) and transient photovoltage (TPV) techniques. The results revealed that photogenerated charge separation efficiency in Zn(0.8)Cd(0.2)S was enhanced and the photogenerated electrons were trapped by the loaded CuS, which benefits photo-reduction. Those were the reasons for significant enhancement in the photocatalytic H2 evolution from water splitting.