Studies On Preparation Of Nanometer Titanium Dioxide By Sol-Gel Method And SWNTs Modifying Titanium Dioxide

With attractive application prospect,nanometer material is called "a new materials in 21th Century",which is one of the hottest materials research after the Internet and Gene.Nanometer Titanium dioxide(TiO₂),especially its anatase phase,is one of the most promising photocatalysts because of its high photocatalytic activity,excellent chemical stability,excellent dielectric properties,low cost and non-toxicity,and it is widely applied in coatings,solar cell,antibacterial materials,waste water treatment and self-cleaning materials.TiO₂ is one of the most hopeful photocatalysts materials. Although research on TiO₂ materials is comprehensive,the property deficiency still exists in TiO₂ materials,which influence actual application values of TiO₂ materials.It has been lately endowed with visible-light response by doping.This thesis is to study the preparation and characterization of TiO₂ nano-film and to explore TiO₂ doping with carbon nanotubes.The pertinent research work has been carried out as follows:Nanometer scale TiO₂ thin film was prepared on glass substrate via sol-gel process combining with spin-coating technology.The thermal reaction process of amorphous gelatin was studied by thermogravimetric-differential thermal analysis(TG-DTA). TG-DTA results show that the change from amorphous to anatase phase at 360-500℃is a gradual process and from anatase phase to rutile phase about 510℃.The films of the structure and phase are characterized by X-ray diffraction(XRD).XRD results show that thin films are amorphous at 400℃calcined and the growth of thin film is almost perfect at 550℃calcined.The mean particle size of anatase phase titania nanocrystals of thin film is 20.6 nm.The morphology of the TiO₂ thin films were studied by atomic force microscopy(AFM),which shows that the films have smooth surface and no crack. Surface structure of the thin film is loose and there is nano-size particles agglomeration in local area at 300℃calcined;Surface structure of the thin film is compact and alignment at 550℃calcined,which the average grain size is about 16 nm.Mechanism of TiO₂ thin-film photoinduced hydrophilicity and micro-structured surface affecting the hydrophilic-lipophilic property were systematically studied with H₂O and C₆H₆ as model.Photocatalytic properties of TiO₂ films is tested with degradation of methyl orange.Surface roughness is the important factor strongly affecting hydrophilic-lipophilic property.The best hydrophilic-lipophilic property is abtained when asurface is the most of rough.To some degree,the smaller size of particle of the film is,the better hydrophilic-lipophilic and photocatalyst property are.Thickness decreases and porosity decreases with the increase of temperature,property is perfect at 600℃calcined.Carbon nanotubes was prepared by electric arc method.High-purity SWNTs was prepared by the gas phase catalytic oxidation.TiO₂/SWNTs coupled Photocatalyst was prepared by sol-gel method.The heat-treatment process,morphology and phase Structure of samples by means thermal gravimertic analysis(TGA),transmission electron microscope(TEM),scanning electron microscope(SEM)and X-ray diffraction(XRD). The results show that SWNTs has good thermal stability and purity at 550℃,SWNTs doping TiO₂ can inhibit the TiO₂ of particles to be largen,0.9 TiO₂/SWNTs(0.9 denotes the quality percentage of SWNTs)shows the best photoactivity.