Highly efficient visible-light-driven photocatalytic hydrogen production on Cu7S4/Zn0.2Cd0·8S p-n binary heterojunctions

In this work, a series of ZnxCd1-xS solid solutions are firstly prepared by a solvothermal process. The optimized composition of ZnxCd1-xS solid solution is determined to be Zn0·2Cd0.8S. On this basis, the Cu7S4/Zn0·2Cd0·8S composite photocatalyst with a binary p-n heterojunction has been synthesized by a co-precipitation process followed by a solvothermal method. Owning to the synergistic effect of the heterojunction structure in the interface of Cu7S4 (p-type) and Zn0·2Cd0·8S (n-type) and the built-in electric field in binary p-n heterojunction, the as-prepared Cu7S4/Zn0·2Cd0·8S composite photocatalyst exhibits a significantly improved photocatalytic activity toward hydrogen production from water with visible light response, which is approximately 5.0 times and 16.5 times higher than of pristine Zn0·2Cd0·8S and CdS, respectively. The possible photocatalytic mechanism has been proposed basing on a series of experimental results. The current work might be valuable inspirations for designing highly efficient heterojunction composite photocatalyst for solar hydrogen evolution.