Enhanced photocatalytic degradation properties of nitrogen-doped titania nanotube arrays

Nitrogen-doped TiO2 nanotubes array were synthesized to improve the photocatalytic efficiency by annealing the anodized titania nanotubes with ammonia at 500 °C. Detailed structural analysis revealed that the nitrogen-doped titania nanotubes are of highly ordered structure, and exhibit a decreased phase transformation temperature compared with those that are not doped, as evidenced by the decrease in full width at half maximum (FWHM) of the (110) peak of rutile phase and the occurrence of the typical Raman peaks of rutile phase at 196, 235, 442, 610 cm−1. According to the photocatalytic degradation of methyl orange under visible light irradiation, the nitrogen-doped TiO2 nanotubes exhibit enhanced photocatalytic efficiency compared with their non-doped nanotubes, which might be a result of either the nitrogen doping induced band gap narrowing or the synergistic effect produced by both nitrogen and fluorine dopants.