The Preparation Of Titania And The Investigation Of Their Photocatalytic Property

Recently, the preparation and application of functional materials are becoming the hotspot in materials research, especially those with special properties on the optical, electrical, magnetic, mechanical fields. As a semiconductor, titania has attracted the attention of researchers, not only for the outstanding physical and chemical properties, but also for the unique properties and promising applications in energy and environment fields.In this paper, the preparation of particles and the Fe-doped nanotitania particles were discussed. Also, the effects of preparation methods and experiment conditions on the structure and performance of materials were investigated. Besides, possible formation mechanism and the photocatalytic activities for the particles were studied. The morphologies and properties of the particles were investigated by TEM, SEM, XRD and UV-vis spectra, and so on.The summarized researches and the results are as follows:(1) Nanotitania particles were synthesized via sol-gel method both in ethanol/water and acetone medium with titanium butoxide as precursor. By finely control of the reaction parameters, particles with different diameters were fabricated, and the effects of those parameters were investigated, such as pH, reaction temperature and catalysts. TEM was utilized for the morphology of the particles, and XRD for the crystal structure. Based on the results, anatase particles can be directly obtained by low-temperature aging method in ethanol/water medium, and size-controllable titania particles were synthesized with ethyl glycol used as chelating agent in acetone medium. The particles obtained via both methods could be well dispersed with a narrow size distribution, with the effect of the acid catalysts on the morphology and structure of the particles in sol-gel process.(2) The chelating sol-gel method was modified to increase the precursor concentration in acetone medium, and size-controllable titania particles were synthesized successfully. By changing the types of acids and the concentrations of titanium butoxide, particles with the diameter ranged from 52 nm to 942 nm could be prepared. The effects of the acids used as catalysts and the formation mechanism for the particles were discussed. The as-synthesized amorphous particles were converted to anatase and then to rutile after thermal treatment at 500℃and 800℃, respectively. The photocatalytic activities of the particles after calcinated at 500℃were investigated with Rhodamine B as organic pollutants. It seemed that the smaller titania particles exhibited higher photocatalytic activities. Further more, the impurity effect for the particles were studied.(3) Fe-doped titania particles were prepared by hydrothermal treatment with the particles obtained in acetone medium. The particles after calcination could retain their spherical structure through hydrothermal process. The morphology and the properties of the particles were systemically studied. It was found that Fe ion was precipitated on the surface of the titania particles as hemitate phase. Diffuse reflectance spectra were utilized for the absorption property of the Fe-doped particles. The dye degradation experiments under UV and sunlight were carried out for the photocatalytic activity of the Fe-doped particles. It seemed that the Fe doping could increase the photocatalytic activity efficiently.