Effect of surface defect states on Zn(1−x)CdxS for enhanced photocatalytic hydrogen evolution

Photocatalytic H 2 production using solar energy has received great attention, but suffers from low photocatalytic efficiency. Herein, Zn (1−x) Cd x S solid solution with different Zn/Cd molar ratio was synthesized by a solvothermal method, and tested for photocatalytic H 2 production from water. The bandgap, charge carrier separation efficiency and surface defect states of the Zn (1−x) Cd x S can be adjusted by altering the Zn/Cd molar ratio. The separation efficiency of photogenerated electrons and holes was greatly enhanced with the Zn/Cd molar ratio of 0.8:0.2. Moreover, the Zn 0.8 Cd 0.2 S exposed most surface defect states compared to those of other Zn (1−x) Cd x S, which can be act as electron pools and active sites for improving photocatalytic H 2 production. Therefore, when the molar ratio of Zn/Cd is 0.8:0.2, the Zn 0.8 Cd 0.2 S exhibited the best performance for photocatalytic H 2 production with the H 2 production rate of 7.71 mmol·g -1 ·h -1 , which is much higher than that of ZnS (17 μmol·g -1 ·h -1 ) and CdS (5.37 μmol·g -1 ·h -1 ). This work provides an in-depth understanding of the surface defect states for enhancing the photocatalytic H 2 production.