Characterization and photostability of Cu2O–Ag–AgBr/Al2O3 for the degradation of toxic pollutants with visible-light irradiation

A plasmonic photocatalyst Cu2O–Ag–AgBr supported on mesoporous alumina (Cu2O–Ag–AgBr/Al2O3) was prepared by deposition–precipitation methods. The samples were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicated that Cu2O–Ag–AgBr nanojunctions were formed by the contact of Cu2O, AgBr and Ag with each other. The catalyst showed high photocatalytic activity and stability for the degradation of toxic persistent organic pollutants under visible light irradiation. The release of metal ions from the catalyst was significantly inhibited during the photodegradation of pollutants. Four interfacial electron transfer process were verified in the photoreaction system of Cu2O–Ag–AgBr/Al2O3 on the basis of electron spin resonance and cyclic voltammetry analyses under a variety of experimental conditions. The results indicated that the coupling of Cu2O with Ag NPs and AgBr not only accelerated interfacial electron transfer processes, leading to the fast photoreduction of the dissolved Ag+ and the photostability of Cu2O. These findings could be useful for the practical application of plasmonic visible light photocatalyst and photovoltaic fuel cells.