Preparation and visible-light photocatalytic activity of Ag3VO4 powders

Monoclinic structure Ag3VO4 was prepared by precipitation method and evaluated for the decolorization of azodye acid red B (ARB) under visible light irradiation (λ>420 nm). The Ag3VO4 prepared in the excess vanadium or silver exhibited higher visible-light-driven activity than the sample prepared in a stoichiometric ratio. X-ray diffraction and UV–vis diffuse reflectance measurements indicated that the excess vanadium or silver in the preparation increased the crystallinity and absorbance in visible light region, resulting in an increase in the photocatalytic efficiency. Furthermore, the activity of the Ag3VO4 was increased by 3.8 times when a NiO was loaded. It was due to the formation of a short-circuited microphotoelectrochemical cell on the surface of NiO/Ag3VO4, enhancing the separation of photogenerated electron–hole pairs, which was proved by ESR studies.