Photocatalytic oxidation of thiophene over cerium doped TiO2 thin film

Abstract Samples of TiO 2 and TiO 2 doped with 2% and 8% cerium ions were prepared by a sol-gel method and used as photocatalysts for the oxidation of vaporized thiophene. X-ray diffraction patterns showed a mixed phase of anatase and rutile for TiO 2 , while 2%Ce/TiO 2 and 8%Ce/TiO 2 were dominated by the anatase phase. As seen in the transmission electron microscopy image, the particle size of Ce/TiO 2 was about 10 nm which was smaller than the undoped TiO 2 . The extended x-rays absorption fine structures revealed the substitutional effect of cerium in the TiO 2 structure. Cerium-doped TiO 2 exhibited a smaller photocurrent compared to that of TiO 2 , which suggested the electrons were trapped by cerium ions. In situ diffuse reflectance infrared spectroscopy under UV irradiation and x-ray photoemission spectroscopy were used to investigate the photocatalytic oxidation of thiophene on the prepared catalysts. Doping of cerium ions in TiO 2 resulted in an enhanced adsorption of thiophene on the catalyst surface. The oxidation products of carboxylic acid with small amounts of sulfate ions were observed. As seen from the infrared absorption spectrum, 2%Ce/TiO 2 and 8%Ce/TiO 2 exhibited higher photocatalytic activity than those of the undoped TiO 2 .