Abstract
This study investigates photocatalytic degradation of nitrogen oxides over titania-based photocatalysts illuminated by ultraviolet and visible light. The TiO 2 photocatalyst was synthesized in a sol-gel process using titanium butoxide as the precursor. After calcination between 150 and 300 °C, the synthesized TiO 2 responded strongly to visible light photocatalytically degrading NO x , probably because of the existence of carbonaceous species that act as sensitizers. The optimum calcination temperature was found to be around 200 °C. Additionally, platinum ion-doped TiO 2 was prepared by impregnation using Pt(NH 3 ) 4 (NO 3 ) 2 as a dopant, which improved the photocatalytic activity that degraded NOx in the visible light region. The Pt ion was doped in oxide form at the surface of TiO 2 and was expected to be responsible for sensitization. At an optimum calcination temperature of around 200 °C, the Pt ion-doped TiO 2 exhibited higher activity in the further oxidation of NO 2 to NO 3 - clearly reducing NO 2 selectivity. The TiO 2 catalysts chemically prepared by either the sol-gel process or impregnation exhibited stronger activity than conventional TiO 2 when illuminated under a fluorescent lamp. Rinsing with water was responsible for the restored reactivity of prepared TiO 2 catalysts for NO x degradation. © 2006 American Chemical Society.