Rare Earth Doped Nano <sub> Of Tio 2 </ Sub> Thin Film Photocatalytic Characteristics

With the development of industry, environmental problems become more and more serious. Controlling and dealing with environment pollutions have being the most serious task which arouse researchers of many countries to pay attention to it. Many methods have been used for disposing contaminations, such as physical adsorption, chemical oxidation, microorganism treatment process and high-temperature incineration, among of those methods the multiphase photocatalysis is superior. This method is favored by many people for the properties of high activity, complete oxidation, utilization asunlight and oxygen (in water phase), especially for some contaminations impossible treat by biochemical degradation. This technology has been used for environmental protection in American, Japan and Canada. But at present, this technology is limited in the laboratory level in China.The purpose of this thesis is to improve the photocalytic properties of nano-titania films. Studied the microcosmic mechanism of rear earth doped nano-titania films by using various kinds of experiment means, in order to find the essence reason of photocalytic properties and offer theoretical and experimental bases for the design and preparation of photocalysis. This thesis includes four parts:1 .Rare-earth (La, Ce) doped TiO₂ thin films were prepared by sol-gel dip coating method in glass substrate, and were characterized by XRD, AFM, UV-VIS and FT-IR to analyse the effects of rare-earth doped TiO₂ films on the surface topography, the crystal structural and the spectral responsivity range;2.Using the methylene blue as an objective degradation product studied the effect of calcination temperature, rare-earth doped concentration, pH value on nano- TiO₂ thin films and analyzed the reaction kinetic of rare-earth doped nano- TiO₂ thin films;3. The effect of La-doped nano- TiO₂ thin films on the heat-induced hydrophilicity and light-induced hydrophilicity were analyzed.The results show that rare-earth doped TiO₂ will cause the crystal expansion and the crystal lattice distortion; the grains size are around 10-13nm after calcination under 400℃; La-doped will restrain the transform of anatase structure to rutile structure and elevate the phase transforming temperature, but Ce-doped couldn't achieve this effects; rare-earth doped TiO₂ will result in red shift and widen the spectrum absorption range; after calcination at 400℃the photocatalytic efficiency of rare-earth doped TiO₂ will better than pure TiO₂. TiO₂ with 0.5mol% doped La express the best photocatalytic efficiency which arrive to 98.2%, whereas the best Ce-doped concentration is 1mol% and the photocatalytic efficiency is 78.8%, therefore exist the optimal doping concentration and calcination temperature. Under the optimal condition, the photocatalytic efficiency of La doping is better than Ce doping; the reaction kinetics of rear-earth doped TiO₂ thin film were analyzed founding it according with the first order reaction equation; 0.5mol% La-doped TiO₂ thin film can maintain a long time heat-induced hydrophilicity at dark environment and the light-induced hydrophilicity also better.