Study On The Preparation And Photocatalytic Property Of TiO₂ And Titanate

Titanium dioxide,a photocatalyst,has received a great deal of attention owing to its advantages such as high chemical stability,non-toxicity and low cost etc.But only under UV, TiO₂ can be excited because of its wide band gap.And the electrons from the valence band to the conduction band and the holes in the valence band are easy to recombine,which restricts the application of TiO₂.Thus Photocatalyst with higher activity and efficiency is an essential for its application in large scale.Doped TiO₂ has been proved to be a simple and efficient technic to improve the photoactivity.In this paper,there are different methods to improve the photocatalyst of TiO₂,including high-temperature calcinations based on the sol-gel,and search proper temperature of the formation for TiO₂ mixed crystal.And then,choose HMT to synthesize N:TiO₂ using ball-milling.By the way,the photocatalyst of Ag/TiO₂ is prepared by a simple chemical reduction method.At the same time,synthesize the Titanate by doped various metals.After that modify A-ion and B-ion with other metals,and discover the best amount of dopant.The impact of reaction condition on crystal phase,crystallization degree,and photocatalytic activities of methylene blue degradation are particularly investigated.Finally,the samples were characterized by Differential Thermal Analysis and Thermal Gravimetric analysis(DTA-TG),X-ray diffraction(XRD) and Scanning Electron Microscopy(SEM).The conclusions of the paper show:a.550℃is the best calcination temperature of TiO₂ in sol-gel,the mixed crystal of TiO₂ is formed.The experiment also shows that too high or low temperature of the calcinations is harmful to the photocatalytic activity.b.Both in sunlight and UV-light,the photocatalysis of N:TiO₂ using bail-milling method is much better than the mixed crystal of TiO₂ and the best amount of dopant in N: TiO₂ is 10%.c.In UVlight,the photocatalysis of Ag/TiO₂ prepared by a simple chemical reduction method is much better than the mixed crystal of TiO₂,but not good in the sunlight.The best amount of dopant in Ag/TiO₂ is 1%.d.SrTiO₃,NiTiO₃,Ce₂TiO₅,La₂TiO₅,CoTiO₃ and ZnTiO₃ are synthesized by sol-gel under 550℃.Among these catalysts,the photoeatalytic activity of CoTiO₃ is worse than others,and SrTiO₃ is the best. e.Doping Zr⁴⁺ and Ba²⁺ for SrTiO₃ by sol-gel can greatly improve efficiency of photocatalysis.But there is a best amount of dopant.The research indicates that with more dopant,the photoeatalysis is worse.The best amount of dopant in Zr:SrTiO₃ and Ba.SrTiO₃ are 8%and 6%.