Ultra-Fast Degradation of Methylene Blue by Au/ZnO-CeO2 Nano-Hybrid Catalyst

Abstract

Au/ZnO-CeO<inf>2</inf> hybrid structure was prepared by in-situ synthesis of 15–20 nm CeO<inf>2</inf> particles in aqueous environment, in which ZnO particles (400–500 nm) were dispersed, using surfactant assisted precipitation method. Au was loaded on prepared structures through the reduction of AuCl<inf>3</inf> by ascorbic acid. TEM analysis and Raman spectroscopy showed that synthesized hybrid structure is composed of both hexagonal ZnO and cubic CeO<inf>2</inf> phases. While methylene blue test solution was degraded totally within 8 min in the presence of Au/ZnO-CeO<inf>2</inf> hybrid catalysis, use of Au/ZnO and Au/CeO<inf>2</inf> led to a significantly low degradation rate (about 22% and 11%, respectively). As proven by XPS analysis the incorporation of ZnO to CeO<inf>2</inf> seem to trigger the formation of Ce+3/Ce+4 dynamic equilibria and this enhances the catalytic efficiency enormously. © 2017 Elsevier B.V.