Preparation, Characterization And Photocatalytic Activity Of TiO₂(B) Nanofibers

Among various semiconductor photocatalysts, nano-sized TiO₂ has been widely investigated due to its non-toxicity, high photo catalytic activity, strong oxidation capability and long-term photostability. Usually, TiO₂ powdered photocatalysts show a high photocatalytic activity owing to their larger specific surface area. However, the powdered photocatalysts are difficult to be separated completely and reused from a slurry system after the photocatalytic reaction. Compared with the conventional nano-sized powder photocatalysts, one-dimensional TiO₂ photocatalysts can be readily separated and reused from a slurry system after the photocatalytic reaction due to their microscale structure. Therefore, we think that this one-dimensional TiO₂ structure is one of the ideal and novel photocatalysts for the applications in the environmental purification and treatment. In this thesis, the TiO₂(B) nanofiber photocatalysts were prepared and their microstructures and photocatalytic activities were investigated and discussed. The main points could be summarized as follows:TiO₂(B) nanofibers were prepared via a hydrothermal treatment of TiO₂ powders (P25) in a 15 M NaOH solution at.l70℃for 72 h and then calcined at 300-500℃. The as-prepared TiO₂(B) nanofibers were characterized by XRD, SEM, TEM, UV-vis and N₂ adsorption-desorption isotherms. The pore volume and specific surface area of the samples decreased with the increasing calcination temperature. The band gap of TiO₂(B) nanofibers was 2.96 eV, close to the band gap of anatase. The photocatalytic activities were evaluated by the photocatalytic degradation of rhodamine B aqueous solution. The results indicated that TiO₂(B) nanofibers had obvious photocatalytic activity and the rhodamine B in the solution could almost be degraded completely after UV irradiation for 5 h. Especially, the TiO₂(B) nanofibers calcined at 400℃and 500℃showed high photocatalytic activities. This is ascribed to the fact that the TiO₂(B) nanofibers have smaller crystalline size, larger pore volume and specific surface area. The successful preparation of TiO₂(B) nanofibers provides some new opportunities for the development of novel photocatalysts.Futrthermore, TiO₂(B) nanofibers were also prepared using four kinds of raw materials by the same method. The experimental results indicated that the crystalline structure of TiO₂ in the raw materials had no obvious effect on the morphologies, pore sizes and specific surface areas of the TiO₂(B) nanofibers.