Preparation and characterization of TiO2 photocatalysts co-doped with iron (III) and lanthanum for the degradation of organic pollutants

Titanium dioxide photocatalysts co-doped with iron (III) and lanthanum were prepared by a facile sol–gel method. The structure of catalysts was characterized by X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples were evaluated by the degradation of methylene blue in aqueous solutions under visible light (λ > 420 nm) and UV light irradiation. Doping with Fe3+ results in a lower anatase to rutile (A–R) phase transformation temperature for TiO2 particles, while doping with La3+ inhibits the A–R phase transformation, and co-doping samples indicate that Fe3+ partly counteracts the effect of La3+ on the A–R transformation property of TiO2. Fe-TiO2 has a long tail extending up the absorption edges to 600 nm, whereas La-TiO2 results in a red shift of the absorption. However, Fe and La have synergistic effect in the absorption of TiO2. Compared with Fe3+ and La3+ singly doped TiO2, the co-doped simple exhibits excellent visible light and UV light activity and the synergistic effect of Fe3+ and La3+ is responsible for improving the photocatalytic activity.