Enhancing the visible light photocatalytic performance of ternary CdS-(graphene-Pd) nanocomposites via a facile interfacial mediator and co-catalyst strategy

By embedding noble metal palladium (Pd) into the interfacial layer matrix of graphene (GR) and semiconductor CdS, we have successfully constructed ternary CdS-(GR-Pd) nanocomposites with intimate interfacial contact. The CdS-(GR-Pd) nanocomposites show remarkably enhanced photocatalytic activity toward selective redox reactions under visible light irradiation as compared to blank-CdS and the optimum binary CdS-GR. It is revealed that the photocatalytic performance enhancement of CdS-(GR-Pd) is ascribed to the optimized spatial charge carrier transfer across the interface resulting from the introduction of Pd nanoparticles as mediators into the interfacial layer between GR and CdS. One role of Pd is to serve as electron reservoir to directly trap photogenerated electrons from CdS and the other role is as interfacial mediator to promote electron relay in the ternary CdS-(GR-Pd) photocatalysts along with conductive graphene as dual co-catalysts. Moreover, the negative light "shielding effect" of GR can be partially counterbalanced through such a facile strategy. This work substantiates the feasibility of adopting the "interfacial-mediator" strategy to optimize the interfacial charge carriers transfer pathway and efficiency for improved photoactivity of GR-semiconductor nanocomposites toward target photoredox reactions.