Ag/ZnO/graphene oxide heterostructure for the removal of rhodamine B by the synergistic adsorption-degradation effects

Herein we demonstrate a facile solution-based process for the fabrication of ternary Ag/ZnO/graphene oxide (GO) composite materials where both Ag and ZnO nanoparticles are deposited on few-layer GO sheets. The obtained composite was found to exhibit remarkably enhanced light-harvesting ability ranging from 200 to 800 nm. Moreover, the Ag/ZnO/GO composite presented improved removal efficiency toward a representative dye molecule, rhodamine B (RhB), by synergistic adsorption-degradation effects derived from the specific Ag/ZnO/GO heterostructure. It is suggested that the heterostructure promotes electron-hole separation and charge transfer in the interface under UV light irradiation, whereas, under visible light illumination, only electrons from sensitized RhB move to the conduction band (CB) of ZnO, and finally transfer to Ag or GO. Subsequently, reactive oxygen species (ROS) generated in the photocatalytic reactions are responsible for the enhanced photocatalytic degradation activity. High-surface-area GO sheets are also considered to play an important role in determining the adsorption efficiency of RhB. Our findings suggest that the obtained Ag/ZnO/GO nanocomposite will be a promising material for the elimination of organic pollutants in the environment.