Single step green synthesis of Au/ZnO/rGO nanocomposites for visible light photocatalytic application

Abstract

A simple and eco-friendly approach for the formation of ZnO/rGO and Au/ZnO/rGO heterojunctions has been achieved using Date Seed Extract (DSE). A simultaneous formation of ZnO nanoparticles and reduction of graphene oxide (GO) takes place in the presence of DSE. In the presence of Au (III) ions, the deposition of Au nanoparticles has been achieved to form Au/ZnO/rGO Nanocomposite. The as synthesized nanocomposites have been characterized using different techniques. The TEM and XRD investigations clearly describe the well dispersed smaller and more uniform Au nanoparticles (15–20 nm) on Wurtzite ZnO (30–40 nm) as compared to bigger and less uniform nanomaterials prepared without DSE. The photocatalytic activity of the as synthesized nanocomposite has been evaluated for the photocatalytic oxidation of Methyl Orange (MO) under solar light irradiation. It was found that the photocatalytic oxidation of MO was greatly enhanced when using Au/ZnO/rGO compared to ZnO/rGO. Photocatalytic modification can be readily assigned to the visible light sensitization of ZnO induced by the surface plasmon absorption of the embedded Au nanoparticles. In addition, the synergetic effect between ZnO/rGO and Au nanoparticles enhances the charge carrier separation and the electron transfer properties. Moreover, lower photocatalytic activity for MO oxidation were obtained when using the nanomaterials prepared by chemical method. The results reveal the role of DSE for modifying the properties of the synthesized nanomaterials.