Studies On Controlled Synthesis Of Nanosized TiO₂ Films And Their Properties

Nanosized TiO₂ sol was prepared by low temperature liquid phase polymerization process.By controlling the addition of structure modifier,acetic acid,diethyl amine, sodium oleic acid and sodium stearate,small particle,rod-like,spindle-shaped,spherical and fascicle-like TiO₂ particles could be obtained.Dip-coating method was applied to preparae thin films.After drying and calcination,the macroproperties such as photocatalytic activity,hydrophilicity,antibacterial activity and adhesion were investigated,The micro-properties including crystalline,surface structure,absorption spectrum,thermal weight loss were also presented.For acetic acid modifier,when TNB:CH₃COOH=1:0,1:2 and 1:4,little particle, rod-like and spherical xerogel,nanosized particles of TiO₂ can be obtained.The spherical particles film that calcinated at 550℃for 2 h has the best performance with contact angle was less than 6.0°and the degradation rate of methyl orange solution of 92.7%under ultraviolet radiation light after1 h.For diethyl amine modifier,under optimized preparation conditions,xerogel particles with rod-like structure could be obtained.After film formation and calcination at 350℃for 2 h,SEM characterization showed the original rod-like structure disintegrated,while the transition temperature from anatase to rutile decreased,and rutile content reached 26.5%. The contact angle of the film was 7.8°and the degradation rate of methyl orange solution reached 85.9%.For oleic acid modifier,when added at a concentration of 16.mmol.L^-1,homogeneous spindle nanosized TiO₂ xero-gel particles can be obtained.Spindle TiO₂ film calcined at 350℃for 2 h had the best photocatalytic activity and hydrophilicity.The contact angle of the film was less than 6°and the degradation rate of methyl orange solution reached 92.9%. Nano-TiO₂ film had stable spindle-like structure.Spectroscopy characterization showed that the spindle film had more "red shift" than small particle film.For sodium stearate modifier,when added at a concentration of 0.02 mol.L^-1 homogeneous fascicle-like TiO₂ gel can be prepared.Calcinated at 500℃for 2 h,the contact angle of the film was less than 5°and the degradation rate of methyl orange solution reached 92.6%.Rutile Content at that time has been 29.2%,the thin-film showed obvious "red shift". Meanwhile,as prepared nanosized SiO₂ sol in sol-gel method was utilized to prepare composite membrane,one step and two-step methods were used to prepare SiO₂/TiO₂ films. The composite film with 15%SiO₂ has the best photocatalytic activity and hydrophilicity. The contact angle of the film was less than 5°and the degradation rate of methyl orange solution reached 89.7%.The films all had favorable photocatalytic activity,hydrophilicity, antibacterial activity,adhesion to the substrate glass.