Study On The Preparation And Photocatalytic Activity Of Titanium Dioxide Nanoparticles

Nanocrystalline titanium dioxide (TiO₂), regarded as the best photocatalyst for its high efficiency, nontoxity, biological and chemical stability, and low cost, has been widely used in many fields such as degradation of environment pollutants, water-splitting for hydrogen production, antibacteria, dye-sensitized solar cells, et al. and has also brought people huge economic, social and environmental benefits. However, the study about TiO₂ as photocatalyst is not enough at the same time. For instance, the preparation technology and photocatalysis efficiency still needs to be improved.Different nanocrystalline TiO₂ powders were synthesized using TiCl4 which is relatively cheaper in comparison with other precursors by hydrothermal and precipitation methods at different conditions respectively. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and N2 adsorption-desorption. Then the photocatalytic activity of the samples was evaluated in the degradation of methyl orange under UV light.Rutile, mixtures of brookite and rutile TiO₂ powders were obtained by hydrothermal method, whose structures and performance were changed depending on the hydrothermal conditions. Among the as-prepared powders, the sample prepared at 160℃for 18h, whose ratio of crystalline phase is 22/78(B/R) and crystallite size is about 21.3nm, has the best photocatalytic activty. And the degradation rate of methyl orange can be 76.5% when the ultraviolet irradiation time is 30min(300W).Mixtures of anatase and rutile TiO₂ powders were synthesized via precipitation method with the modifier C3H6O. The samples, calcined at 400℃⁶00℃, have good partile distribution, high crystalline and purity. On the basis of the study, a series of AgCl/TiO₂ photocatalysts were prepared by the same method with different dosages of AgNO₃. The photocatalytic activity of the samples (with and without AgNO₃) were evaluted by also researched by degradation of methyl orange, and the AgCl/TiO₂ nanocrystalline powder (mAgNO₃/mTiO2=0.25%) has the best photocatalytic activity.