Research On Co-doped Photocatalyst TiO₂ To Modify Its Photocatalytic Activity

In the realm of photocatalysis, we can utilize nanometer photocatalyst to make the infinite light energy converting into the electric power and the chemistry energy. At present,the nanometer technology develop in rapid speed,then provided good opportunity for the technical application of the nanometer photocatalysis,so the photocatalysis technique becomes the hotspot in science research nowadays.Its application is very extensive,such as wastewater treatment,air decontamination,make use of solar energy,anti-virus, defend fog and autoclean function etc.. Nano TiO₂ can degradate the poisonous heavy metals and most organic pollutant by photocatalytic oxidation in water and air, include dye, surfactant, and various nonbiodegradable toxic organic pollutant,its final degradation product is H₂O, CO₂ and nontoxic ion or salts. TiO₂ photocatalytic oxidation is considered the most prospect in advanced wastewater treatment for its nontoxicity,chemical stability,inexpensiveness and non-secondary pollution. But,the semiconductor TiO₂-based photocatalysis technology still exists two key difficult problems of science and technology: both of the quantum production and the utilization of solar energy are low. This thesis aims at those two difficult problems of nanometer TiO₂,we do a series of experiment,research modifying TiO₂ by doping metal or nonmetal and optimization of preparative conditions,in order to improve its photocatalytic activity and absorbability in visible light irradiation.First,this topic study the preparation method of TiO₂ and effect of each preparation condition on photocatalytic activity.the result show,hydrolysis temperature, aging time and temperature, dry temperature and time have little effect on the catalyst activity ,but the solution proportions, pH and calcination temperature are key factors that influence the catalyst activity,especially the calcination temperature, because it define the crystalline phase and partical size of TiO₂.Then,we studied metal and nonmetal doping or co-doped catalyst TiO₂ to modify its photocatalytic activity. This experiment adopt sol-gel method to prepare pure or doped TiO₂. Under the high-pressure mercury lamp and xenon lamp,namelyultraviolet and visible radiation,to test its photocatalytic activity by degrading methyl orange. Compare a series of experiment data, we get: doping Gd and Ho ,two kinds of rare earth elements,have obviously rose T1O2 photocatalytic activity in ultraviolet radiation,in parallel,the nonmetal N-doped make the TiC?2 absorption wave-length occurrence red shift,raising its light catalyst activity in the xenon lamp. The best calcinations temperature of pure TiO2 > TiC?2-Gd -. TiCVHo -. T1O2-N ^ TiO2-Gd-N and T1O2-HO-N is 400°C, 600°C > 550°C, 400°C, 500 °C and 500°C respectively. Generally speaking,the metals blend of T1O2 at the higher calcination temperature,the result is better;but nonmetal blend in the lower calcination temperature have better effect.