Photocatalytic Performance of NiS/CdS Composite with Multistage Structure

Construction of heterojunctions between semiconductors is a significant way to promote the photocatalytic performance by improving the photogenerated charge separation. Herein, CdS with multistage structures (sphere, flower, and wheat) were first synthesized, and their photocatalytic activities of hydrogen production were not too high as massive electrons and holes are rapidly recombined. NiS/CdS composites were then prepared by depositing NiS nanofragments on the CdS surface, which exhibited higher photocatalytic activity (about 13-fold) than pure CdS. The enhanced reason is the effective charge separation and transfer (Z-scheme charge migration) formed between p-type NiS and n-type CdS, which is confirmed by Mott–Schottky plots and density of states. Moreover, the NiS/CdS composite shows much more efficient charge transfer than pure CdS, indicated by photocurrent response and photoluminescence. Therefore, this study offers an important strategy for the design of multistage structural photocatalysts with a p–n heterojunction to improve the charge separation.