Highly enhanced photocatalytic properties of ZnS nanowires-graphene nanocomposites

ZnS nanowires (NWs)-graphene (GR) nanocomposites were successfully synthesized via an easy electrostatic self-assembly method. The results showed that ZnS NWs were well dispersed on the surface of the graphene nanosheets, forming ZnS-GR nanocomposites. The photoluminescence intensity of the ZnS-GR nanocomposites exhibited a clear quenching in comparison with that of the ZnS NWs. The ZnS-GR nanocomposites were used as photocatalysts for the degradation of methylene blue (MB) under UV light irradiation. After irradiation for 1 h, the degradation efficiency was 21.69% for ZnS NWs, 31.52% for ZnS-0.5 wt% GR, 58.69% for ZnS-3 wt% GR, 88.33% for ZnS-5 wt% GR and 80.74% for ZnS-7 wt% GR, indicating that ZnS-5 wt% GR nanocomposites had the highest photocatalytic activity. The kinetic rate constant of the ZnS-5 wt% GR nanocomposites was about 16 times higher than that of the ZnS NWs. The mechanism of the highly enhanced photocatalytic properties was attributed to the efficient separation of the photogenerated electron-hole pairs and the high specific surface area of graphene.