Improvement of thermal stability of nitrogen doped titania photocatalyst by addition of surfactants during solvothermal treatment

The TiO_2-x N _y nanocrystals with beige color were prepared by homogeneous precipitation-solvothermal process in TiCl ₃-hexamethyleneamine-alcohol solutions with the addition of various surfactants, such as sodium dodecylbenzenesulfonate (SDBS), n-hexadecylamine (HAD), and n-hexadecyltrimethylammonium chloride (HTAC) at 190 °C for 10 h. The phase composition, crystallinity, microstructure, specific surface area, nitrogen doped amount, and photocatalytic activity of titania powders greatly changed depending on pH value and other reaction conditions. The TiO _2-x N _y powders prepared by solvothermal treatment with surfactant additives followed by calcination in air at 400 °C showed smaller particle size, larger BET specific surface area and higher photocatalytic activity than those without surfactant. The TiO_2-x N _y powders showed excellent visible-light absorption, thermal stability and photocatalytic activity for nitrogen monoxide destruction under irradiation of both visible-light and UV-light irradiation. About 40% and 60% nitrogen monoxide could be continuously removed with the residence time of 1.9 min by the TiO_2-x N _y photocatalyst under irradiation of visible-light (λ > 510 nm) and UV-light (λ > 290 nm), respectively.