Synthesis And Surface Modification Of Nanometer TiO₂ And Their Photocatalytic Activity

Nanometer TiO₂ materials have high specific surface area, strong absorption to ultraviolet light, high stability, efficient photocatalytic activity, and no pollution to environment, which make them a promising material for applications. This thesis includes the following aspects:1,Four nanometer TiO₂ with various crystal phases were prepared by sol-gel method at low temperature, using TiCl4 and tetrabutyl titanate as raw materials. The crystal structure and morphology of the nanoparticles were characterized by XRD and SEM. Their surface structure, light absorption property and band gap energy were studied by FT-IR and UV-Vis diffuse reflection spectra. Methyl orange and rhodamine B were photodegraded in Visible light and UV light, respectively. The influence of the crystal phase of the TiO₂ catalyst and light source on their activities was investigated, and compared to the commercial P25. It was found that the photocatalytic activities of the as-prepared products are higher than that of the P25 except the rutile TiO₂. This indicates that the photocatalytic activity is related with the crystal phase, particle size and band gap energy of the catalyst.2,Using C7H13BrN2, C9H4F6NP and PEG as template, series of porous, mainly mesoporous, TiO₂ were synthesized by ultrasound-microwave and hydrothermal method, respectively. The influence of the synthetic method, template, temperature and the ratio of Ti:template on structure and property of TiO₂ were investigated. The crystal structure, morphology and particle size of the products were characterized by XRD and SEM. The BET surface area and pore size were obtained by N2 adsorption-desorption experiment. Photodegradation activities of the TiO₂ on rhodamine B in visible light were studied. It was found that the particle size of products prepared by hydrothermal method was small and the pore distribution is narrow. The photocatalytic efficiency of the TiO₂ prepared with different ratio of source material to template was different.3,Series of rhodamine B-sensitized TiO₂ were prepared and the real adsorbed quantity of the dye was calculated. The influence of the adsorbed quantity of the dye on catalytic activity of the product was studied by photodegradation of MO in visible and UV lights. The results show that the photocatalytic activity of sensitized rutile TiO₂ is higher than that of the pure rutile TiO₂. Series of CuO doped TiO₂ were prepared using home made rutile TiO₂ as raw material. Since we can not observe the existence of Cu from X-ray diffraction result, X-ray photoelectron spectroscopy of the 0.5% CuO-TiO₂ was examined as a sample. The result proved the existence of Cu in the Cu-doping sample. The Ti 2p bands were broadened and the photocatalytic activity of the doping product was improved.