Fabrication of a direct Z-scheme type WO3/Ag3PO4 composite photocatalyst with enhanced visible-light photocatalytic performances

A direct Z-scheme type photocatalyst WO3/Ag3PO4 composite (molar ration 1:1, 1W/1Ag) was prepared by hydrothermal method. The 1W/1Ag was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), UV-vis diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence emission spectroscopy (PL) etc. technologies. The photocatalytic performances were evaluated by degradation of methylene blue (MB) and methyl orange (MO), and their removal rates were up to 95% after 60 min and 90% after 180 min, respectively. The prepared 1W/1Ag exhibits a much higher photocatalytic activity than pure Ag3PO4 and pure WO3 under visible light irradiation. The apparent rate constants of MB and MO degradation on 1W/1Ag are about 2.4 and 2.5 times that of pure Ag3PO4, respectively. The enhanced performance of the 1W/1Ag is attributed to a synergistic effect including relatively high surface area, strong light absorption, matched energy band structure, and the improved separation of photogenerated charge carriers between the two components. A reasonable Z-scheme mechanism referring to directed migration of photoinduced carriers was proposed. Thus, it can be suggested that the 1W/1Ag can serve as a promising photocatalyst for environmental purification and clean energy utilization. (C) 2016 Elsevier B.V. All rights reserved.