Hydrothermal Synthesis of Nitrogen-Doped Titanium Dioxide and Evaluation of Its Visible Light Photocatalytic Activity

Nitrogen-doped titanium dioxide (N-dopedTiO2) photocatalyst was synthesized from nanotube titanic acid (denoted as NTA; molecular formulaH2Ti2O5·H2O) precursorviaa hydrothermal route in ammonia solution. As-synthesized N-dopedTiO2catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffuse reflectance spectrometry, X-ray photoelectron spectroscopy, electron spin resonance spectrometry and Fourier transform infrared spectrometry. It was found that nanotube ammonium titanate (NAT) was produced as an intermediate during the preparation of N-dopedTiO2from NTA, as evidenced by the N1sX-ray photoelectron spectroscopic peak ofNH4 +at 401.7 eV. The catalyst showed much higher activities to the degradation of methylene blue and p-chlorophenol under visible light irradiation than Degussa P25. This could be attributed to the enhanced absorption of N-dopedTiO2in visible light region associated with the formation of single-electron-trapped oxygen vacancies and the inhibition of recombination of photo-generated electron-hole pair by doped nitrogen.