Doped Titanium Dioxide Nanoparticles Preparation And Photocatalytic Performance

Nanocrystalline titanium dioxide finds a broad field of realized and potential applications in the areas of photocatalysis. However, titanium dioxide only absorbs 5% of the spectrum of the incoming sunlight in the near ultraviolet region, which clearly limits its efficient application. Numerous studies have been performed to extend the photoresponse of TiO2 and to improve its photoactivity by modifying its surface properties, composition etc. Selective doping of the crystalline matrix has been proved to be an efficient route to improve the photoactivity of semiconducting oxides, and the effect is dramatic for titania when it is doped with various metal cations. Recently, there are a number of studies related to the photocatalytic activity of doped TiO2 catalysts for the purpose of improving its photocatalytic activity, including Fe, Au, W etc. Because its physical and optical properties are greatly modified, doped semiconductor photocatalysts increase the efficiency of photocatalytic process by increasing the charge separation and extending the energy range of photoexcitation .In this paper, La-doped, La-Fe co-doped, In-doped and In-Fe co-doped nanocrystalline titania dioxide were prepared by sol-gel. The gels were dried by frozen-dry technology, then, the nanoparticle powders were prepared by being heated at 400 C.The nanoparticle powders were charactered by X-ray diffraction, scanning electron microscophy, laser diffraction particle size analyzer. The result showed that the samples were rutile and well -proportioned, Their particle size were 50-60 nm.Nano-TiO2 with close crystalline size and having different doped ions, were prepared. The photocatalytic activity was evaluated by the photocatalytic decomposition of methyl orange, butylrhodamine-B and printing and dyeing waste water and the influence of the dopants and their concentration to the effeciency of photocatalic activity were discussed. It was found that co-doping nano-TiO2 has better performance, their optimism concentration are 0.02%La/0.05%Fe and 0.1 % In/0.05 % Fe.Using the dipping-drawing method, the nanopartilce TiO2 films were prepared on glass. The influence of the thickness and the dopant element on the efficiency of photodegrading the methyl orange were discussed. It was showed that 5 layers were the best and co-dopant can improve the photocatalytic activity of the nanopartilce TiO2 film.