Preparation Of Co-doped TiO₂ Photocatalysts And Their Photocatalytic Activities Under Visible Irradiation

1.Preparation of chromium and sulfer co-doped TiO2 photocatalysts and their photocatalytic activities under visible irradiationPure and doped or co-doped TiO₂ catalysts with various amounts of chromiumwere obtained by sol-gel process, in which tetrabutyl titanate was used as precursor and chromium nitrate, thiourea as ion donors. Photodegradation experiments showed that co-doped catalyst has higher photocatalytic activity than that of pure and single doped ones, the co-doped catalyst with 0.6% (molar ratio) chromium, 1.2% (molar ratio ) sulfer, calcinated at 500℃was of the highest catalytic efficiency under visible irradiation. The doped catalysts were characterized by XRD,BET,XPS and UV-vis to have anatase phase, higher specific area, and wide range of visible response. The higher visible light photocatalytic activity of co-doped TiO₂ was attributed to the doped chromium that lowered the band gap and expanded the absorption of visible light region, the doped sulfer that maintained the charge balance and enhanced absorption to visible light.2. Preparation of TiO2 photocatalysts based on molecular sieve and their photocatalytic activities under visible irradiationCr-SBA-15,Ti-SBA-15,Ti-Cr-SBA-15,Ti-Cr-S-SBA-15 catalysts were obtained by In-situ synthesize method in which P123 as template, tetrabutyl titanate, chromium nitrate and thiourea as raw material and ion donors. The method was simple and can save much time as well as materials. Photodegradation experiments showed that Ti-Cr-S-SBA-15 catalyst has the highest photocatalytic activity under visible irradiation. The catalysts were characterized by XRD,BET,XPS,TEM and UV-vis to have anatase phase of TiO₂, high specific area, the hexagonal mesoporous structure was remained well and wide range of visible response. The structure of SBA-15 enlarged external area of catalysts which added the active centers for reaction, the doped chromium lowered the band gap and expanded the absorption of visible light region, the doped sulfer maintained the charge balance and enhanced absorption tovisible light.