Preparation of a titanium dioxide photocatalyst codoped with cerium and iodine and its performance in the degradation of oxalic acid

A novel class of visible light-activated photocatalysts was prepared by codoping TiO2 with cerium and iodine (Ce–I–TiO2). The particles were characterized using the Brunauer–Emmett–Teller method, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–Visible light absorption. Particles of Ce–I–TiO2 had greater photoabsorption in the 400–800 nm wavelength range than iodine-doped TiO2 (I–TiO2). The effects on the photocatalytic degradation of oxalic acid under visible light or UV–Visible light irradiation were investigated. The photocatalytic activity of Ce–I–TiO2 calcined at 673 K was significantly higher than that of Ce–I–TiO2 calcined at 773 K and I–TiO2 calcined at 673 K in aqueous oxalic acid solution under visible light or UV–Visible light irradiation. Under visible light irradiation, oxalic acid was first adsorbed on the surface of the catalysts rather than reacted with free radicals in the bulk solution, and then oxidized by OHads to CO2, which was verified by studying the effects of nitrogen purging and scavengers, as well as by gas chromatography/mass spectrometry.