THE EFFECT OF CRYSTAL FORM OF N-DOPED TITANIUM DIOXIDE ON VISIBLE-LIGHT PHOTOCATALYTIC ACTIVITY

TiO2 samples with different crystal forms were treated in flowing NH3 at elevated temperatures to fabricate N-doped TiO2 photocatalysts with different crystal forms. The resulting N-doped TiO2 photocatalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffusion reflectance spectrometry, and X-ray photoelectron spectroscopy. The visible-light photocatalytic activity of the catalysts was evaluated by measuring the photocatalyzed removal rate of propylene. Results indicate that the visible-light activity of N-doped TiO2 photocatalysts is highly dependent on the crystal form. Namely, N-doped anatase TiO2 has the highest visible-light activity, while the visible-light activity of N-doped TiO2 photocatalysts decreases with decreasing content of anatase phase and increasing content of rutile phase. In addition N-doped rutile TiO2 has no visible-light photocatalytic activity.