Iron Ion Doping Of Tio <sub> 2 </ Sub>-based Self-cleaning Glass

Environmental purification using TiO₂ photo-catalysts has attracted a great deal of attention with the increasing number of recent environmental problems in the world. However, the use of conventional powder catalysts results in disadvantages in stirring during the reaction and in separation after the reaction. Preparation of the catalyst coated as thin film will make it possible to overcome these disadvantages and to extend its industrial applications.In order to overcome the faults of the powder catalysts and to enhance the photo-catalytic activity of TiO₂, in this thesis, the surface structure and the properties of the self-cleaning glass were studied. The self-cleaning glass with Fe-TiO₂ photo-catalytic thin film coated on slide glass was prepared by sol-gel progress from the system Ti (OC₄H₉)₄-NH (C₂H₄OH)₂-C₂H₅OH-H₂O containing FeCl₃. The microstructure and properties of the films were studied by using differential thermal and thermo-gravimetric analysis (DTA-TG), X-ray photoelectron spectroscopy (XRD), scanning electron microstructure (SEM) and infrared (IR) methods. The effects of the amount of Fe addition and the thickness of the Fe-TiO₂ thin film on the photo-catalytic activity were examined by degrading the solution of dichlorvos. The hydrophilic property of the self-cleaning glass was studied by measuring the contact angle. The transmittance of the self-cleaning glass was studied.The results show that: the photo-catalytic thin film is mainly composed of Fe₃O₄ and TiO₂ particles of 10-100 nm. The addition of appropriate amount of Fe³⁺ is effective for improving the photo-catalytic activities of TiO₂. At [Fe]/[TiO₂](mol ratio)=0.005, the highest photo-catalytic activity is obtained when the glass is coated for nine times. With increasing of the amount of PEG addition to the precursor solution, the quantity and size of pores were increased in the resultant thin films as a result of the decomposition of PEG during heat-treatment. At the same time, it would have the larger size and more pores.The results of contract angle measurement showed that with increasing of the quantity and size of pores the hydrophilic property of the as-prepared porous thin films was enhanced and the contract angle between water and the porous TiO2 thin films quickly dropped to zero. With increasing of the thickness of the thin film and the amount of 2000PEG addition to the precursor solution, the transmittance of the self-cleaning glass decreased.