(517e) S Doped TiO2 synthesized By Novel One Step Liquid Flame Spray Pyrolysis (LFSP) for Photocatalytic Oxidation of CO in Visible Region

A novel single step Liquid Spray pyrolysis (LFSP) method is used to synthesize a series of S-TiO₂ catalyst of nanosized crystals with dimensional homogeneity and high monodispersity. In order to improve the visible light response and to further narrow the band bap of TiO₂ catalyst, Sulphur is used as the dopant in this method. With the change in the amount of S incorporated into TiO₂ catalyst, we observed the generation of the successive energy bands inside the TiO₂ band gap thus lowering the bandgap energy. The effects of nanosized S doped TiO₂ catalyst on the visible light photocatalytic oxidation of gaseous CO were investigated. Our XPS results indicate that the nitrogen doping concentration could reach up to 8 wt% owing to the homogeneous doping in the mesoporous TiO₂ catalysts. The nitrogen doped TiO₂ catalyst exhibit such excellent characteristics as high specific area, relatively small particle size, pure anatase phase and excellent UV-vis absorption capacity in the range of 400-800 nm, which are all beneficial to the photocatalytic oxidation of CO under the visible light irradiation. The photo conversion of CO to CO₂ is quantitative in the presence of O₂. The photocatalytic CO oxidation rates and the amounts of N deposited on TiO₂ surface show a close correlation. The addition of water vapor dose not affects significantly the CO photooxidation kinetics in the presence of O₂. The main oxidants in CO Photocatalytic oxidation seem to be produced from adsorbed O₂. The photocatalytic oxidation kinetics was investigated in detail as a function of S loading, coated TiO₂ mass, CO concentration, O₂ concentration, light intensity, additives, and humidity. These interesting results will be discussed in the presentation.