Preparation And Photocatalytic Properties To Research Of Modified TiO₂ Hollow Microspheres

With the rapid development of China’s economy,people’s living standards have been greatly improved,but also brought serious water environment pollution,water pollution accounted for a large proportion of organic matter,so explore the rapid degradation of organic pollutants in water,water pollution treatment is of great significance.In this paper,based on semiconductor photocatalytic oxidation technology,using titanium dioxide photocatalyst has good chemical stability and excellent catalytic oxidation performance,can effectively degrade organic pollutants.However,TiO₂has defects such as wide gap and easy recombination of photoinduced charge,which reduces its photocatalytic performance and limits its practical application.Therefore,in view of the inherent defects of TiO₂,hollow TiO₂microspheres were prepared by hard template method to increase the specific surface area of TiO₂,and modified by precious metal deposition and semiconductor recombination methods to expand the spectrum absorption range and improve the separation efficiency of photoborne carriers.The main contents and results of the study are as follows:（1）TiO₂ hollow microspheres were successfully prepared by hydrothermal method using carbon microspheres as template and tetrabutyl titanate as titanium source.When the addition amount of carbon microspheres was 0.4 g,1-2 um hollow microspheres with relatively complete structure were prepared.In the photocatalytic degradation experiment of rhodamine B,the degradation rate of xenon lamp irradiation for 30 min was 64%,1.6 times that of Non-hollow microsphere TiO₂.After four cycles of photocatalytic degradation of rhodamine B,the loss of photocatalytic activity was only 4%.Compared with TiO₂with non-hollow structure,TiO₂with hollow microsphere structure can make incident light reflect and refract inside the microsphere for many times,which increases the absorption capacity of the material to incident light,generates more photogenerated electrons,and improves the photocatalytic performance of the material.（2）Using carbon microspheres as template,tetrabutyl titanate as Ti source and Ag NO₃as Ag source,Ag/TiO₂materials with hollow microspheres were prepared by hydrothermal method and photochemical precipitation method.It was proved by PL spectroscopy,solid uv diffuse reflectance spectroscopy and electrochemical workstation that the Ag elements deposited on the surface of TiO₂would transfer to photogenerated electrons in the TiO₂conduction band,which promoted the separation of photogenerated electron holes.In the experiment of photocatalytic degradation of Rhodamine B,when the compound amount of Ag in Ag/TiO₂hollow microspheres was 3%,the degradation rate of Rhodamine B was the highest,and the degradation rate was 82%after 30 min irradiation with xenon lamp,which was 1.2 times that of TiO₂hollow microspheres.After four cycles of photocatalytic degradation of rhodamine B,the loss of photocatalytic activity was only 5%.（3）Using carbon microspheres as template,g-C₃N₄/TiO₂materials with hollow microspheres were prepared by hydrothermal method and calcination method,tetrabutyl titanate as Ti source and melamine as carbon and nitrogen source.The addition of g-C₃N₄can effectively promote the separation of photogenic electron hole pairs of TiO₂and expand the spectral absorption range of the material by PL spectroscopy,solid-state Visible-Ultraviolet diffuse reflectance spectroscopy and electrochemical workstation.In the experiment of photocatalytic degradation of Rhodamine B,when the mass ratio of hollow TiO₂microspheres to melamine was1:6,the g-C₃N₄/TiO₂hollow microsphere composite had the highest degradation rate of Rhodamine B,and the degradation rate of Rhodamine B reached 90%after 30 min of light exposure,1.4 times that of TiO₂hollow microsphere.After four cycles of photocatalytic degradation of rhodamine B,the loss of photocatalytic activity was only 7%.