The Preparation And Their Photocatalytic Performance Of TiO₂ Photocatalysts

With in-depth study of the semiconductor photocatalyst,semiconductor photocatalytic degradation of organic wastewater has been from the laboratory to industrialization.In many semiconductor photocatalyst,titanium dioxide,with its green nontoxic,stable property,simple preparation and low cost advantages,such as stand out,most of those in the semiconductor photocatalytic materials.But as a result of the forbidden band width of the titanium dioxide is bigger,its only in the ultraviolet area smaller than 387 nm wavelength range has good light catalytic activity,and its photoproduction electronic-hole pair recombination rate is higher,compound within a very short time,which leads to the low utilization rate of quantum problem,so the researchers used a variety of methods to be modified,including metal and nonmetal doping,transition ions doping,co-doping,precious metal modification,dye sensitization,semiconductor composite and load curing technology.This article improved the photocatalytic activity of TiO₂ by doping and composite modification.And by degradation of methyl orange solution to evaluate the photocatalytic activity of the samples in visible and ultraviolet light.The main research contents are as follows:First,Nano titanium dioxide photocatalyst was prepared by Sol-gel method.The results showed that the photocatalytic activity of TiO₂ photocatalyst under visible light was low and under UV light was high.Titanium dioxide nano powder is formed by the accumulation of nano particles,and its size were reached nano scale.The degradation rate of methyl orange solution?10 mg/L?was 27.91% after 5h irradiation under visible light and 96.08% under UV light.Second,based on the shortages of TiO₂ a series of Ag+ doped TiO₂ photocatalysts were prepared by sol-gel method and the photocatalytic activity of the samples were studied.It revealed that,Ag+ doping decreased the crystallinity of TiO₂,but the crystal structure was not changed.After introducted the Ag+ ions,the band gap of TiO₂ photocatalyst could be decreased and the utilization rate of the electron hole can be improved.When Ag+ doping amount was 1.00%,TiO₂ photocatalyst had the highest photocatalytic activity whether under visible or ultraviolet light conditions.Under visible light,the degradation rate reached 92.57% whendegradation 4 h.Under UV light,the degradation rate reached 84.54% when degradation 2 h.Third,the Si O2/TiO₂ compound catalyst was synthesized by sol-gel method.It revealed that Si O2/TiO₂ compound catalyst had the better photocatalytic activity,this was because of the formation of the heterojunction structure,which could improve the electron hole separation and transport rate and further improved its photocatalytic activity.The optimum compound of Si O2 was 3.00%.Forth,Si O2/TiO₂ compound photocatalyst was prepared by sol-gel method,and then choosen 0.20 g which has the best photocatalytic activity of Si O2/TiO₂ composite photocatalyst impregnated with different concentration of silver nitrate solution,the silver modified Si O2/TiO₂ compound catalyst was synthesized..It revealed that,after the Si O2/TiO₂ was immersed in silver solution,the photocatalytic activity was further improved.The best concentration of silver nitrate solution was 3.00×10-5mol/L.The results showed that the TiO₂ and its metal ions doped,noble metal deposition and semiconductor composite photocatalyst could successfully synthesized by sol-gel method,and the photocatalytic activity of TiO₂ was greatly improved.