Defective Cd 0.3 Zn 0.7 S twin crystal/Ag 3 PO 4 Z-scheme heterojunctions toward optimized visible-light-driven photocatalytic hydrogen evolution.

To improve the photocatalytic performance of semiconductor catalysts, one of the most widely used strategies is to combine two or more semiconductors with appropriate energy band structures to construct heterojunctions for an extended light absorption range and effective charge separation. Here, a novel Z-scheme heterojunction is fabricated via the Cd 0.3 Zn 0.7 S twin crystal and the narrow band gap semiconductor Ag 3 PO 4 . The resulting Cd 0.3 Zn 0.7 S/1%Ag 3 PO 4 photocatalyst exhibits excellent photocatalytic hydrogen production capability (167.29 μmol h -1 ), which is two times higher than that of Cd 0.3 Zn 0.7 S and 44/7 times higher than that of pristine ZnS/CdS. The excellent photocatalytic performance is not only attributed to the defective twin crystal structure of Cd 0.3 Zn 0.7 S but also related to the well-matched Z-scheme interface between Cd 0.3 Zn 0.7 S and Ag 3 PO 4 , and both factors effectively promote the separation of the photogenerated electron-hole pairs and prolong the lifetime of the carriers, being responsible for the excellent photocatalytic hydrogen evolution performance of the catalysts. This strategy provides new insights into the construction of efficient twin crystal heterojunctions for photocatalytic hydrogen evolution with high performance.