Preparation and characterization of N-TiO_2 photocatalyst with high crystallinity and enhanced photocatalytic inactivation of bacteria

摘要

This study reports the synthesis, characterization and environmental applications of nitrogen doped TiO_2 photocatalyst in the form of powder and film. N-TiO_2 photocatalysts were synthesized via the hydrolysis of titanium tetraisopropoxide using urea as the nitrogen source. The crystalline structure, particle size and specific surface area of the resultant N-TiO_2 nanoparticles were investigated by x-ray powder diffraction and the Brunauer-Emmett-Teller method. The results showed that a mixture of anatase and brookite phases was formed at pH 1 after annealing the powder at 450°C for 4 h, in contrast to a pure anatase phase at pH 3. UV-vis spectral characterization showed that the absorption region of the as-prepared N-TiO _2 was extended to the visible light region. Stable sols could be achieved by controlling the molar ratio of water-to-titanium precursor and pH of the sols. During the photocatalytic test, in comparison to the standard commercial photocatalyst Evonik-Degussa P25 and home-made bare TiO_2 nanoparticles, the N-TiO_2 particles exhibited enhanced photocatalytic performance for degradation of methylene blue (MB) dye. The visible light induced photocatalytic inactivation of the obtained nanopowders and nanofilms on bacteria (Escherichia coli) was evaluated. The N-TiO_2 nanomaterials showed higher bactericidal activity under visible light irradiation.