Layer-by-layer assembled synthesis of hollow yolk-shell CdS–graphene nanocomposites and their high photocatalytic activity and photostability

Herein, we successfully synthesized, for the first time, a diameter of 340 nm hollow yolk-shell type CdS–graphene composite photocatalyst with a hollow core and an independent void space with 5~10 nm between hollow CdS core and graphene (GR) shell with the thickness of about 2 nm (denoted as hollow CdS@@GR), by the bottom-up method using the template-guided layer-by-layer self-assembly process. The formation mechanism of hollow CdS@@GR nanocomposites was proposed. Due to the unique hollow structure that can absorb more light, more dye, and catalyst molecules and the synergistic effect between hollow CdS core and GR shell with void space, hollow CdS@@GR showed enhanced photocatalytic performance. In addition, GR shell can effectively protect CdS from photocorrosion, and even after five repeated runs, the recycled nanocomposites exhibited superior stability. Moreover, we also proposed the possible photocatalytic mechanism of such nanostructures based on free radical capturing experiments and fluorescent probe technique. The design and fabrication of the hollow yolk-shell structured nanocomposites will provide a new potential route for other stable and efficient photocatalysts to satisfy versatile solar energy conversion.