N-doped TiO2 nanotubes with visible light photo-activity for degradation of methyl orange in water

Abstract

N-doped TiO2 nanotubes were prepared by a wet process and with an additional thermal treatment. Firstly, titanate nanotubes were prepared by a hydrothermal chemical method. Then the obtained nanotubes were immersed in a 0.5 mol/L NH3 solution for different periods. Finally, the resulted products were calcinated at high temperature to complete the substitution of O by N. The prepared N-doped nanotubes had an anatase structure and a large specific surface area. For those N-doped TiO2 nanotubes, a significant shift of the absorption edge to a lower energy region and a notable decomposition of methyl orange in an aqueous solution under visible light irradiation were observed. The most visible light active catalysts were those immersed in a 0.5 mol/L NH3 solution for 10 h and then calcinated at 400°C for 1 h.