Visible-light induced photocatalytic activity of TiO2−xAy (A = N, S) prepared by precipitation route

Nitrogen doped or nitrogen/sulfur co-doped titania photocatalyst TiO2−xAy (A = N, S) which can be excited by visible light were prepared by mixing aqueous TiCl3 solutions with various nitrogen sources such as hydroxylamine (NH2OH), hexamethylenetetramine (HMT, C6H12N4), urea ((NH2)2CO) and thiourea ((NH2)2CS) followed by hydrothermal treatment at 190 °C. The titania powders prepared using hydroxylamine consisted of rutile crystals with non-homogeneous size distribution. The nitrogen doped titania powders prepared using hexamethylenetetramine consisted of mainly mono-size spherical brookite crystals, whereas those using urea and thiourea consisted of belt-like rutile particles. The TiO2−xAy (A = N, S) powders showed excellent visible-light absorption and photocatalytic ability for the oxidative destruction of nitrogen monoxide under irradiation of visible light. The effect of reaction solvents on the phase composition, specific surface area and photocatalytic activity was also characterized.