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

The TiO2 xNy nanocrystals with beige color were prepared by homogeneous precipitation-solvothermal process in TiCl3-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 TiO2 xNy 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 TiO2 xNy powders showed excellent visible-light absorption, thermal stability and photocatalytic activity for nitrogen monoxide destruction under irradiation of both visible-light and UVlight irradiation. About 40% and 60% nitrogen monoxide could be continuously removed with the residence time of 1.9 min by the TiO2 xNy photocatalyst under irradiation of visible-light (k > 510 nm) and UV-light (k > 290 nm), respectively.