Photocatalytic activity for degradation of nitrogen oxides over visible light responsive titania-based photocatalysts

This study investigates photocatalytic degradation of nitrogen oxides over titania-based photocatalysts illuminated by ultraviolet and visible light. The TiO2 photocatalyst was synthesized in a sol-gel process using titanium butoxide as the precursor. After calcination between 150 and 300 degrees C, the synthesized TiO2 responded strongly to visible light photocatalytic ally degrading NOx, probably because of the existence of carbonaceous species that act as sensitizers. The optimum calcination temperature was found to be around 200 degrees C. Additionally, platinum ion-doped TiO2 was prepared by impregnation using Pt(NH3)(4)(NO3)(2) as a dopant, which improved the photocatalytic activity that degraded NO, in the visible light region. The Pt ion was doped in oxide form at the surface of TiO2 and was expected to be responsible for sensitization. At an optimum calcination temperature of around 200 degrees C,the Pt ion-doped TiO2 exhibited higher activity in the further oxidation of NO2 to NO3-clearly reducing NO2 selectivity. The TiO2 catalysts chemically prepared by either the sol-gel process or impregnation exhibited stronger activity than conventional TiO2 when illuminated under a fluorescent lamp. Rinsing with water was responsible for the restored reactivity of prepared TiO2 catalysts for NOx, degradation.