| To date, titanium dioxide as a model of nano-semiconductor photocatalysts not only gets the widespread concern of domestic and foreign researchers, but also becomes the first choice for industrial applications because of its stable chemical properties, superior photocatalytic activity, non-toxic, low cost and so on. However, traditional TiO2has many bottlenecks such as low utilization efficiency of sunlight, uncontrollable morphology and poor thermal stability,which hinder their scale business and industrialization.Therefore, N-doped mesoporous titania nanocrystals with high photocatalytic activity in visible light irradiation were succeeded to be synthesized with tetrabutyl titanate as Ti sorce.What’s more, the process conditions, preparation methods, modified means and water treatment functional application with Methylene blue (MB) as a probe were mainly studied in this paper. We used XPS, XRD, UV-Vis DRS, FT-IR and N2adsorption-desorption to characterize the samples. The contents of this paper included three sections following.In the first part, We compared advantages and disadvantages of sonochemical method, hydrothermal method and sonochemical-hydrothermal method to optimize the methods. The results showed that the three different experimental methods had no significant effect of phase composition of TiO2. But the samples prepared in ultrasound-hydrothermal process had not only small particle size, big surface area and pore volume, but also uniform pore size distribution and ordered mesoporouspore. In addition, they had the best visible-light photocatalytic activity. The MB degradation rate was up to99.65%after180min visible light irradiation. Both synergies made the performances of the prepared samples significantly better than the other two methods, which provided a new idea to the study of TiO2preparation methods.In the second part, Nitrogen-doped TiO2nano-crystalline were prepared successfully by sonochemical-hydrothermal method with dodecydiamine(DADD) as template as well as nitrogen source. The influence of templates on TiO2performance was explored by setting blank control experiments without adding templates. The results showed that the templates added not only contributed to increasing the specific surface area and pore volume of the product with playing a role in making pores and regularing pores, and will also substantially improve the visible light photocatalytic activity of TiO2by achieving the effective nitrogen doping by getting two nitrogen species of nitrogen substituents and interstitial nitrogen. This provides a new material of both as template and nitrogen source and new direction.In the third part, Different nitrogen doping mesoporous TiO2nanocrystalline were prepared varing different preparation conditions by sonochemical-hydrothermal method with dodecydiamine(DADD) as template and nitrogen source, and pH as the main influence factor. The results showed that different pH values of reaction system had significant influence on the crystalline, pore structure, photocatalytic activity of prepared samples. Through comparison, the TiO2specific surface area prepared from the reaction system of which pH value is7reaches as high as135.8m2/g, and the double pores formed had regular shape and were evenly distributed. High visible light photocatalytic activity was found and the degradation rate of10mg/L methylene blue aqueous solution reaches as high as99.65%under visible light after180minutes’ irridiation. The main results may be that the pH value of the reaction system changed the electric charge of both ends of DADD, and which together with exiting forms and the hydrophilic-hydrophobic property of DADD will make difference of prepared samples on pore structures and morphology, and in last influence the adsorption property and photocatalytic activity of TiO2. |
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