Visible light photocatalytic activities of ZnFe2O4 loaded by Ag3VO4 heterojunction composites

The heterojunction structure was formed between monoclinic scheelite Ag3VO4 with an average diameter of about 50 nm and spinel ZnFe2O4 with an average particle size of about 500 nm by calcining the mixed semiconductors. The composite samples were characterized by X-ray diffraction, UV-vis absorption spectrum, scanning electron microscope and nitrogen physical adsorption. The prepared ZnFe2O4/Ag3VO4 composite demonstrates very high activity in photodegradation of Rhodamine B under visible light irradiation (lambda >= 420 nm). Its degradation constant (k) is about 11 times higher than that of N-doped TiO2. The remarkable photocatalytic activity of ZnFe2O4/Ag3VO4 could be explained by the inter-semiconductor electron-hole transfer mechanism caused by the matched band positions of the two semiconductors. Moreover, the transient photocurrent-time performance, the involved active species, the role of oxygen, and the effect of pH values on photocatalytic activity were also investigated. (C) 2012 Elsevier B.V. All rights reserved.