Doped Modification And Application Of Titania Photocatalyst

Owing to nontoxicity, high efficiency, low cost and stable performance corrosion resistance, titania has been the best promising materials. However, due to its wide bandgap (3.2eV for anatase), TiO₂ can be excited only with UV light, which accounts for only a small fraction of solar light (5%). Therefore, it is highly desirable to develop TiO₂-based photocatalysts with enhanced activities under visible light. For the sake of efficient use of sunlight, the technology of enlarging the absorption scope of TiO₂ by doping or modifying TiO₂ may then appear as an appealing challenge for developing the future generation of photocatalysts.In order to overcome this limitation, this research focuses on the doping modification of TiO₂ which can inhibit the recombination of photo-generated electron-hole pairs. All of these are to find a best mode to improve photocatalysis efficiency so that TiO₂ can take full advantage of visible light. Research contents and results are as follows:1. Noncompensated doping: For the n-type codoped elements, the chromium and nitrogen doped TiO₂ nanoparticle was prepared by the solvothermal method and sol-gel method. These samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-visible light photometer (UV-Vis DRS). The results showed that the particle size of the codoped titania is narrowed to about 9 nm when the molar ratio of Ti, N, O is 1:2:10%. The absorption peak redshifts to 400nm and the light absorption intensity also increased in order to effectively improve the photocatalytic activity. The intrinsic band gap calculated from the experimental data is narrowed to 1.8 eV for co-doping, and the variation tendency of the bandgap is consistent with that of the experiment.2. Compensated doping: For the p-type codoped elements,? the vanadium and nitrogen doped TiO₂ sample was also prepared by the solvothermal method. When the nitrogen source is urea and the vanadium source is V2O5, the nitrogen\ vanadium atom is incorporated into the crystal lattice in the form of interstitial and V5+, respectively. The indentity of codoped sample exceed greatly that of pure one both under UV light irradiation and visible light irradiation.The degradation rate for methylene blue of N/V-TiO₂ comes up to more than ninety percent after 30min.When the nitrogen source is urea and the vanadium source is C10H14O5V, the size of codoping TiO₂ powders can achieve around 10nm. The light absorption effect of codoped titania (Ti: N: V=1:2:16%) is the best in all samples. The degradation rate for methylene blue of N/V-TiO₂ is ninety percent after 30min.