Tungsten And Non-metallic Doped Titanium Dioxide Preparation And Visible Light To Degrade Organic Dyes

TiO2, a well-known photocatalyst, is widely applied in the field of the degradation of environment pollutant under UV light. However, the narrow band gap of TiO2 (～3.2eV) allows only UV light (wavelength< 400nm) absorption, which accounts for only 4% of solar energy. Besides, the photon efficiency of TiO2 is rather low due to the high electron-hole combination rate. These shortcomings strictly limit the application of TiO2 in the technique of solar energy. Numerous studies have focus on the modification of TiO2 to improve the photocatalytic performance. In this work, W is doped to induce defects on the surface of TiO2, change the crystallinity, decrease the recombination of electrons and holes, and broaden the photon-excited wavelength to visible light range, hence promote the photocatalytic activity of TiO2, especially under visible light irradiation.In the thesis, TiO2 powders and W-TiO2 powders are prepared by sol-gel method, UV method, ultrasonic method. TTOB is used as a titanium source; TiO2 powders and W-TiO2 powders are prepared by hydro thermal method which adopted titanium sulfate as a titanium source, and characterized by various techniques, such as UV-Vis DRS, X-ray diffraction (XRD) and so on. The particle size, absorption spectra and photocatalytic activities of TiO2 and W-TiO2 powders prepared by different methods are studied. The photocatalytic activity of SRB is the best on catalysts prepared by sol-gel method, but the ones prepared by hydrothermal method are the lowest under visible light irradiation.To verify the impact of calcination temperatures on the photocatalytic activity, sol-gel method and hydrothermal method are adopted in the thesis. The samples are characterized by various techniques, such as UV-Vis DRS, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET surface area and so on. The particle size, BET surface area, absorption spectra and photocatalytic activities of TiO2 and W-TiO2 powders prepared at different calcinations temperature are studied. TiO2 and W-TiO2 powders prepared by sol-gel method showed that the photocatalytic activity of catalysts prepared at a higher calcination temperature is poor, TiO2 and W-TiO2 powders calcined at 500℃by hydrothermal method showed better photocatalytic activity.In order to study the synergistic effect of metal and non-metal co-doping, non-metal elements such as N, B, P, S and F are applied as co-dopants, and characterized by various techniques. The study shows that co-doping of P, N, B, S, F and W improve photocatalytic activity of W-TiO2 significantly.