Study On The Preparation And Characterization Of TiO₂ Microsphere And Its Composite

Nano titanium dioxide particles is a kind of important function materials, widely used in photocatalysis, optoelectronics, medicine, sensor devices,gas sensing, pigments or paper whiteners,white pigments for paints and cosmetics,dye-sensitized sollarcells, photochemical degradation of organic pollutants, electrodes in lithium batteries, and so on. The crystalline structure, morphology, and particle size can strongly influence the applications of titanium. Titanium dioxide has three crystalline phases, namely anatase, rutile, and brookite. The crystalline phases differ in their physical properties, such as refractive index, dielectric constant, and chemical and photochemical reactivity.The preparation of TiO₂ nanoparticles includes gas-phase, solid-phase and liquid-phase methods. Sol-gel method is a popular method because it need low temperature, technics is easy and cheap. But the TiO₂ nanoparticles made form sol-gel method are anomalous in shape and the distribution is wide and the nonoparticles is amorphous. The amorphous TiO₂ nanoparticles could be converted into anatase and rutile when annealed them under high temperature. The TiO₂ nanoparticles will sink or mass during the annealing process. Preparation of TiO₂ nanoparticles with good dispersion and crystal strucutre is always a pursuit target.In chapter 2, sphere titanium has been prepared by sol-gel method. We discussed the effect of experiment conditions on the shape and size of titanium. We obtained anatase titanium with hydrothermal treatment and studied the effect of solventhermal treatment conditions on the crystal structure change. The photocatalytic degradation of anatase titanium on methylene blue (MB) was evaluated in a MB solution. The result shows the titanium has very good photocatalytic activity on MB, the MB can be degraded absolutely in 40 min.In chapter 3, the composition of TiO₂ and aqueous CdTe nanoparticles were prepared via sol-gel method. The morphology and structure of the CdTe@TiO₂ composite nanoparitcles were characterized by SEM and TEM instruments and their mechanism of formation was proposed. The investigation of their photoluminescence (PL) properties shows that the PL intensity of CdTe nanoparticles becomes weaker than their parent aqueous solution. These composite nanoparticles exihited similar fluorescence lifetimes, which were shorter than those in the aqueous solution. These experimental results indicate that the CdTe@TiO₂ composite nanoparticles have potential application in the field of solar cells.In chapter 4, we modified the TiO₂ with KH570. TiO₂@PS particles were obtained by dispersion polymerization, in which PVP K360 was used as surfactant and AIBN was used as initiator. TiO₂@PS core@shell nanoparticles were treated by hydrothermal treatment and the TiO₂ cores were transfered to anatase.