Fabrication and Photocatalytic Activity of Highly Crystalline Nitrogen Doped Mesoporous TiO2

Highly crystalline nitrogen doped mesoporous TiO2 photocatalysts were fabricated by the sol-gel method using tetrabutyl titanate as the Ti source, urea as the N source, and polyacrylamide (PAM) and polyethylene glycol (PEG) as the templates, and then by calcining in nitrogen and air. The photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, N-2 adsorption, X-ray photoelectron spectroscopy, and UV-Vis spectroscopy. When the mass ratio of PAM and PEG was 1:4, the sample prepared by calcining at 600 degrees C in nitrogen and 500 degrees C in air had the anatase phase and a mesoporous structure and high crystallinity. The average pore size, crystallite size, and specific surface area were 5.11 nm, 12.5 nm, and 110.8 m(2)/g, respectively. Nitrogen atoms were incorporated into the TiO2 lattice mainly as substitutional N and molecularly chemisorbed gamma-N-2, and a small amount of interstitial N. Nitrogen doping narrowed the band gap and allowed light absorption in the visible light region. Compared with undoped mesoporous TiO2, the absorption band edge of nitrogen doped samples exhibited a red shift and the light absorption intensity was increased. Photocatalytic degradation of methyl orange showed that the nitrogen doped mesoporous TiO2 had a higher photocatalytic activity than undoped mesoporous TiO2 under visible light.