Preparation And Photocatalytic Performance Of Doped Titanium Dioxide Film

Titania is the most effective photocatalyst of resizing erosion、low cost、nontoxicity.However, with its high-energy band gap, titania photocatalysis reacts only underultraviolet light. Doping with metal and nonmetal is the most feasible methods forimproving the photocatalytic performance of titania. So, this study used glass as a carrierand prepared pure TiO₂films, Fe-doped TiO₂thin films and Fe³⁺, N co-doped TiO₂thinfilms. And the photocatalytic efficiency of doped TiO₂photocatalyst was also studied withindoor formaldehyde gas as degradation object.At first, the preparation methods were compared with chemical vapor deposition andsol-gol method. The result showed that the TiO₂film prepared by the sol-gel method wasbetter. The films were uniform and dense. Then, the preparation conditions of sol-gel TiO₂film were designed. The film was prepared by sol-gel method with tetrabutyl titanate（TBOT） as precursor and glacial acetic acid （CH3COOH） as catalyst and ethanol assolvent. The effects of sol aging time, mole ratio of H2O to Ti, coating layers, calcinationtime, and calcination temperature on the photocatalytic activity were investigated. Theresults showed that TiO₂films prepared in2d of sol aging time,227.7:1of mole ratio ofH2O to Ti,1of Coating layers,4h of calcination time,450℃of calcination temperaturehad better photocatalytic activity. The analysis of X-Ray Powder Diffraction showed thatthe TiO₂particles prepared in the same condition were all anatase nano TiO₂particles.The doping Fe³⁺, N can incorporate into the lattice structure of titania, decrease theband gap, and give rise to the response to the visible light. First, the TiO₂films of differentiron doping concentration were prepared using sol-gel method. Then the Fe-TiO₂filmsplaced in CVD. The Fe/N-TiO₂films were prepared in different NH3flow. The resultsshowed that when the iron doping proportion （mole ratio） was1%and the rate of NH3flow was60ml/min, the photocatalytic activity was the best.The photocatalytic degradation kinetics of formaldehyde was studied. The resultsshowed that all the kinetics used pure TiO₂thin films, Fe-TiO₂thin films and Fe/N-TiO₂thin tilms were fitted well with first order kinetic model. The relationship of initialconcentration of formaldehyde and the rate constants was linear. With the increase of initial concentration of formaldehyde, formaldehyde photocatalytic degradation rateconstant decreased.