Glutathione-protected gold nanocluster decorated cadmium sulfide with enhanced photostability and photocatalytic activity.

A Novel glutathione-protected gold nanocluster (Au-GSH NC) decorated CdS photocatalyst was prepared using a chemical self-assembly method. After the photocatalyst was decorated with Au-GSH NCs, the photocatalytic activity and photostability of CdS were remarkably enhanced. Compared to pure CdS, the as-prepared CdS-Pt-Au photocatalyst exhibited 9 times of photocurrent and 2.85 times of photocatalytic activity. More importantly, the photocorrosion of CdS, which is a critical drawback for CdS-based photocatalysts, was significantly suppressed. It is believed that the heterostructures and matched energy levels between CdS and Au-GSH NCs are the key for enhance catalytic activity and photostability. The level of LUMO and HOMO of Au-GSH NCs is higher the conduction band and valence band of CdS respectively. Through the heterostructures, the photogenerated electrons of Au-GSH NCs are injected into the CdS, while the photogenerated holes of CdS transferred to the Au-GSH NCs. The opposite directions of charge migration improves the charge separation efficiency and average lifetime, which drastically enhances the photoactivity, and the rapid transferring of holes from CdS to Au-GSH NCs significantly suppresses the photocorrosion of CdS.