Preparation Of Nano-TiO₂ Films On Glass And Study On Property Of Self-cleaning

Titanium dioxide (YiO₂), as an excellent photocatalyst material, can degrademost organic contaminations which can not been done through chemical andbiologic methods into CO₂,H₂O. Furthermore it costs little and does not producenew contaminations. These advantages lead to a very optimistic application futureof titanium dioxide in the fields of air purification, waste water treatment andself-cleaning. In recent decades, studies on photocatalysis of TiO₂ have attractedconsiderable attention. For the reason of disadvantages of powder, TiO₂ film hasbecome a new focus of study. Soda lime glass is common and low in cost. Highphotoactive TiO₂ thin film on the surface of soda line glass will make it have awidespread application in self-cleaning glass.On the basis of summarization of principle of photocatalysis andhydrophile,problems and prospect, technics of preparation of TiO₂ films on glassthrough sol-gel and relationship to parameters and property of photocatalysis andhydrophile were studied.Because of the deficiencies of narrow absorption range, high recombinationrate of charge carrier and low efficiency of quantization, TiO₂ films doped withFe³⁺ were prepared through sol-gel method. The morphology of the film wasinvestigated by using a scanning electron microscopy (SEM). The grain size andcrystallinity of the films were determined by a X-Ray diffractometer (XRD). The transmittance and the absorption threshold of the films were measured byUV-visible spectrophotometer. Photocatalytic activity of TiO₂ films wasmeasured by photocatalytic decoloration of methyl orange aqueous solution andhydrophilic activity by measurement of angle change of water drop on glassbefore and after UV illumination.The impacts of Fe³⁺ quantity, number of film layer, different lamp-housesand temperature of heat treatment on performance of self-cleaning glass wereinvestigated. TiO₂ thin films doped with Fe³⁺ have better activities of optics,photocatalysis and hydrophile than undoped; overmuch Fe³⁺ will reduce thephotocatalysis and hydrophile activities of the films; appropriate quantity of Fe³⁺not only increases absorption to UV but also makes absorption range "red shift";heat treatment has great influence to film's properties: too low temperaturecannot make TiO₂ transit to anatase crystal which has better photocatalysis andhydrophile activities and too high temperature will transmogrify the substrate ofglass.The TiO₂ films fabricated by dipcoating onto glass substrate for 4 time witha heat treatment at a temperature of 500℃for 1.5 hours were compact, uniformand transparent without iridescent appearance.The films exhibited the mostexcellent hydrophilic and photocatalytic performance when the doping ionconcentration of Fe³⁺ is 0.5%. The obtained TiO₂ films still have superhydrophilic and good photocatalytic ability even under visible light after UVillumination,.