CdS–graphene nanocomposites as visible light photocatalyst for redox reactions in water: A green route for selective transformation and environmental remediation

A series of CdS–graphene (GR) nanocomposites with different weight addition ratios of GR have been fabricated via a facile one-step solvothermal approach. CdS–GR nanocomposites are proven to serve as selective visible light photocatalysts toward aerobic selective oxidation of alcohols and reduction of heavy ions Cr(VI), instead of being nonselective in water. Furthermore, we find that decreasing the defect density of GR by using the solvent-exfoliated graphene (SEG) instead of graphene oxide (GO) as the precursor of GR can efficiently enhance the photocatalytic activity of CdS–GR nanocomposites due to its improved electron conductivity as compared to reduced GO (RGO). In addition, the hybridization of CdS with GR (RGO, SEG) via an intimate interfacial interaction can also effectively inhibit the photocorrosion of CdS during the photocatalytic redox reaction. It is hoped that this work can draw attention to making better use of graphene to synthesize more efficient GR-based nanocomposite photocatalysts for solar energy conversion, especially in the field of diverse redox processes in water in the framework of green chemistry.