Construction of heterojunction ZnFe2O4/ZnO/Ag by using ZnO and Ag nanoparticles to modify ZnFe2O4 and its photocatalytic properties under visible light

In this study, a narrow band gap semiconductor ZnFe2O4 is prepared first and then a wide band gap semiconductor ZnO is used to modify it by using hydrothermal method under the participation of the chelating agent nitrilotriacetic acid (NTA), which will be removed in the process of high temperature baking. The structure and composition of ZnFe2O4/ZnO heterojunction were characterized by using powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-Vis diffuse reflectance spectra (DRS). In order to improve the photocatalytic activity of ZnFe2O4/ZnO heterojunction under visible light irradiation Ag nanoparticles were loaded on its surface by using a very simple and special method namely silver mirror reaction at room temperature without agitation. The methyl orange (MO) was taken as model dyes to illustrate the photocatalytic performance of synthesized products on visible light irradiation. Maximum degradation of 84% for MO was achieved when one 85 W ordinary household energy-saving lamp was used as light source and ZnFe2O4/ZnO/Ag as multicomponent photocatalyst. The photocatalytic degradation reaction kinetics of methyl orange by ZnFe2O4/ZnO and ZnFe2O4/ZnO/Ag were investigated. Better photoelectrochemical performance of ZnFe2O4/ZnO and ZnFe2O4/ZnO/Ag composites provides substantial evidence for its excellent photocatalytic properties. Furthermore, the photocatalytic mechanisms of ZnFe2O4/ZnO and ZnFe2O4/ZnO/Ag composites for methyl orange degradation under visible light were proposed.