Controllable Synthesis And Property Research Of Titanium Dioxide Photocatalysts

Due to its desirable properties, such as chemical inertness, non-toxicity, low cost and relative high photocatalytic efficiency, TiO2 remains the most promising material as photocatalysts, gas sensors, solar cells and white pigment. However, how to improve the photocatalytic efficiency which is mainly caused by the fast recombination of photogenerated electron-hole pairs is still a major challenge in the phtocatalytic research field until now. In this work, we designed and synthesized various TiO2 photocatalytic materials by the methods of doping and compositing, template-directing, as well replication of sisal fiber. The properties and effects of the sample prepared were studied.1. Facile Fabrication of Hollow Mono-dispersed TiO2 SpheresA simple surfactant-assisted coating process was developed to fabricate hollow mono-dispersed TiO2 spheres using TiCl4 solution as a precursor; methacrylic acid functionalized polystyrene spheres (PS) as a template. The whole process could be operated in an aqueous solution. A plausible mechanism was proposed to elucidate the formation of the hollow TiO2 spheres. This simple and low-cost method might be used to produce hollow TiO2 spheres on large scale.2. Characteristics of Hollow TiO2 Fibers via Replication of Sisal FiberHollow TiO2 fibers were synthesized via replicating sisal fiber and characterized by XRD,SEM,BET and TGA-DSC. The products faithfully inherited the characteristics of the template and showed the activity to photodegrade Rodamine B. This facile fabrication method could be expected to use in the synthesis of other metal oxide and metal hollow fibers.3. The preparation and properties of cerium ions doped TiO2The photoreactivity of pure and Ce4+ doped anatase and rutile TiO2 prepared by hydrothermal methods were studied in this paper. The samples were characterized by XRD,TEM,XPS and UV-VIS diffraction spectrum. Photocatalytic results showed that the photocatalytic efficiency of the rutile TiO2 doped with cerium ions was enhanced. However, photocatalytic efficiency of the anatase TiO2 doped with cerium ions greatly decreased. The different effects of cerium ions doping on the properties of anatase and rutile TiO2 might be caused by the different variation of the surface hydroxyl amount.4. Influence of Pt4+ doping on the photocatalytic efficiency of TiO2 studied by technique of laser flash photolysisBy using nanosecond laser to excite colloidal particles of pure and Pt4+ doped TiO2 in aqueous solution, we have monitored the absorption spectrum of O- at about 440nm which is the signal of trapped holes and an active species in the photocatalytic reaction. Results showed that the absorption spectrum decayed within microseconds, the concentration and the decay rate of O-determined the photodegradation efficiency. Thus, nanosecond laser flash photolysis has been carried out to elucidate the drastic enhancement of Pt4+ doping on the photocatalytic efficiency of TiO2.