Hybrid metal-dual sulfide core–shell nanostructures with enhanced photocatalytic properties

In this study, we report a facile cation-exchange method to synthesize three different metal@dual sulfide hybrid nanostructures with enhanced photocatalytic properties. Starting from clusters of Au@Ag₂S with a poorly crystalline shell, excess amounts of Cd²⁺, Zn²⁺ and Pb²⁺ are used to promote the thermodynamically unfavored cation-exchange under elevated temperature. The change of shell compositions accompanies the disassembly of Au@Ag₂S clusters into monodisperse ternary core–shell nanostructures with modulated optical properties. Interestingly, it is found that Au@Ag₂S–CdS outperforms Au@Ag₂S–ZnS and Au@Ag₂S–PbS in the visible-light-driven photodegradation of methylene blue, which can be largely attributed to the improved shell crystallinity, enhanced visible light absorption and appropriate band alignment for charge transfer.