Preparation Of TiO₂-based Photocatalysts And Their Performance In Dye Degradation Reactions

With the development of modern human civilization,the problems of energy shortage and water pollution have become increasingly prominent.Photocatalytic technology is one of the effective ways to solve such problems.The research and development of high-efficiency photocatalysts is the key to promoting the development of photocatalytic technology.Titanium dioxide（TiO₂）has received extensive attention from academia and industry because of its easy preparation,good biocompatibility and excellent chemical stability.However,TiO₂materials have the disadvantages of high electron-hole recombination rate,small specific surface area and high band gap energy,which seriously restrict their industrial application.Therefore,in this paper,starting from the modification of TiO₂photocatalysts,metal element-doped TiO₂-based photocatalysts and non-metallic element-doped TiO₂-based photocatalysts were prepared and successfully applied to the photocatalytic degradation of methylene blue（MB）dyes.At the same time,the characteristics of the photocatalysts and the mechanism of the catalytic experiment were studied through a series of characterization and control experiments.The main results obtained are as follows:（1）Ce,Co,Fe,Mn,Ni,Cu,V,and Mo element-doped TiO₂-based photocatalysts were prepared using a sol-gel method.The study found that metal element doped TiO₂can narrow the forbidden band width of TiO₂photocatalyst,increase the specific surface area,and enhance the photocurrent response of the catalyst.In the experiment of photodegradation of MB aqueous solution,metal element doped TiO₂-based photocatalyst showed better photocatalytic performance than pure TiO₂,among which Mo and V doped TiO₂-based photocatalyst showed outstanding adsorption and catalytic performance,the removal effect of MB can reach 98%within 30 mins.And the modified catalyst also showed good cycling stability and natural photodegradation performance.The catalytic mechanism experiment found that the main active species was hydroxyl radical（·OH）.（2）N-doped TiO₂-based photocatalysts were prepared by calcination method.The study found that N-doped TiO₂can narrow the forbidden band width of TiO₂catalyst and broaden the light absorption range of TiO₂.In the experiment of photodegradation of MB aqueous solution,the photocatalytic performance of N element-doped TiO₂-based photocatalyst is obviously better than that of pure TiO₂.There is a"volcanic"relationship between the catalytic performance and the doping ratio of N element,and the N200-TiO₂photocatalyst has the best catalytic performance,showing a removal effect of 98.4%within 20 mins,and has good stability.Catalytic mechanism experiments found that superoxide radicals（·O₂^-）played a major role in the experiments.