Enhanced photocatalytic activity of fluorine doped TiO2 by loaded with Ag for degradation of organic pollutants

F-doped TiO2 loaded with Ag (Ag/F-TiO2) was prepared by sol–gel process combined with photoreduction method. The physical and chemical properties of the prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), UV–vis diffuse reflectance spectroscopy (DRS), N2 adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). XPS analysis indicated that Ag species existed as Ag0 in the structure of Ag/F-TiO2 samples. UV–vis diffuse reflectance spectra showed that the light absorption of Ag/F-TiO2 in the visible region had a significant enhancement compared with the F-doped TiO2 (F-TiO2). PL analysis indicated that the electron–hole recombination rate had been effectively inhibited when Ag loaded on the surface of F-TiO2. The photocatalytic activities of the samples were evaluated by phenol and X-3B (Reactive Brilliant Red dye, C.I. reactive red 2) degradation under UV light irradiation and visible light (λ > 420 nm) irradiation, respectively. Compared with F-TiO2, the sample of 0.50Ag/F-TiO2 showed the highest photocatalytic activity under both UV and visible light irradiation. The interaction between F species and metallic Ag in the Ag/F-TiO2 samples was responsible for improving the photocatalytic activity.