Ultra-fast degradation of methylene blue by Au/ZnO-CeO2 nano-hybrid catalyst

Abstract

Au/ZnO-CeO2 hybrid structure was prepared by in-situ synthesis of 15–20nm CeO2 particles in aqueous environment, in which ZnO particles (400–500nm) were dispersed, using surfactant assisted precipitation method. Au was loaded on prepared structures through the reduction of AuCl3 by ascorbic acid. TEM analysis and Raman spectroscopy showed that synthesized hybrid structure is composed of both hexagonal ZnO and cubic CeO2 phases. While methylene blue test solution was degraded totally within 8min in the presence of Au/ZnO-CeO2 hybrid catalysis, use of Au/ZnO and Au/CeO2 led to a significantly low degradation rate (about 22% and 11%, respectively). As proven by XPS analysis the incorporation of ZnO to CeO2 seem to trigger the formation of Ce+3/Ce+4 dynamic equilibria and this enhances the catalytic efficiency enormously.