The Preparation Of Ⅰ⁵⁺-doped TiO₂ Film By Molecular Self-assembly Method And The Study On Its Photocatalytic Activity

Current used catalysts, TiO2 is widespread used due to its chemical stability, photocatalytic activity, economy, photochemical corrosion resistence and non-toxicity. A number of doping treatments have been conducted to modify TiO2 in order to improve its photocatalytic activity. Currently, TiO2 composite material has become research focus.In this paper, I5+ -doped TiO2 nano thin film was prepared from low-temperature aqueous system by molecular self-assembly method, on the basis of SH functional group and substrate of quartz glass. Meanwhile, with Methyl Orange as the aimed compound, the effect of various experimental factors on photocatalytic activity of I5+-doped TiO2 thin film was discussed. The main conclusions of this research was shown as follows:1) I5+-doped TiO2 thin film was prepared at room tempreture by molecular self-assembly method, and the pH of the solution was adjusted to 2.0. Results showed that the optimal bathing time of preparing TiO2 was 4h.2) Characterized by different methods, the mechanism of the film forming and interfacial structure of the system were studied. The phrase and growing mode of I5+-doped TiO2 thin film were observed and judged under TEM. Results indicated that the film constituted by granular nanocrystal with diameter of 5nm-10nm had a good effect of crystallization,. Raman spectroscopy further showed that the films mainly rutile and anatase, it was also observed that iodine doped titanium dioxide had an obvious response to visible light through fluorescence emission spectra, with strong fluorescence emission peak at 450nm-500nm.3) With Methyl Orange as the aimed compound, the photocatalytic activity of I5+-doped TiO2 thin film was studied. It was observed that this film was greatly affected by light energy, H2O2, recycle of the film, concentration of objects, doping proportion and substrate material.Specifically, the photocatalytic activities of different I5+ -doped TiO2 films were all improved, presenting the highest level when the concentration of doped I5+ reached 2 mmol/L.4) the decolorization rates of Methyl Orange were 99.5% and 98% respectively in the condition of ultraviolet light and visible light. With the addition of H2O2, the decolorization rate of Methyl Orange solution reached 98% after 1h period of photocatalysis treatment, increasing by 57% compared to the sample without H2O2.5) Under the visible light condition,the decolorization rate of Methyl Orange solution fell from 99.5% to 58% after repeated use of the I5+ -doped TiO2 film, whose activity losted half.The I5+ -doped TiO2 thin film has good effect, but repeatition rate is low, still need in-depth study. Regeneration after deactivation methods 20min ultrasonic treatment in distilled water and ultrasonic treatment in 0.1mol/LH2O2 in 5 hours, the decolorization rate increased by 14.2% and 30.6%.