The Preparation And Properties Of Modified TiO₂ Thin Films

Titanium dioxide (TiO₂) is one of the most promising photocatalysts due to its chemical inertness,non-toxic nature,low cost,and has been studied for decades.Potential application,such as anti-fouling,declorizing,sterilizing,antifogging,self-cleaning,etc.are in prospect. However there were two problem that existed in this promising materia,one is the short lifetime of charge carries resulting from higher rate of electron and hole pairs recombination another is that these photo-induced hydrophilic conversion of TiO₂ films was actived only irradiating with UV light which is only 4% that contained in solar light.How to improve photo-catalytic activity of TiO₂ thin films and increase the light utilization to visible light are the key to technology application of TiO₂ photocatalyst.Therefore,developing high photo-active TiO₂ photocatalyst is of great importance.In order to prepare good TiO₂ thin films,many methods have beenused,including magnetic sputter method,chemical vaper deposition, sol-gel method,etc.Among them sol-gel method is one of the major methods for preparing TiO₂ thin films.However traditional sol-gel method has brought environmental problems because they use abundant organic solution or inorganic strong acid solution to avoid the hydrolyzation of Ti4+ iron.TiO₂ precursor solution by NH3·H2O modified peroxo-titania acid(PTA) method.This new method takes non-iron water as solvent and H2O₂ as complex agent though which it will cause no pollution and low cost.The TiO₂ thin films and Fe,N modified TiO₂ thin films were prepared on glass substrates by peroxo titanic acid (PTA) sol..The influences of different technological process on hydrophilicity and photocatalyst of the TiO₂ thin films were studied by using UV-vis abosorption spectrum,X-ray diffraction,Atomic force microscope,contact angle measurement and decoloration of MB the aim was to find the optimum technology of preparing hydrophilic and photocatalytic TiO₂ thin films.The study of TiO₂ films indicated that the TiO₂ thin films with 4 layers that annealed at 500℃for 2h show the best hydrophilicity,the water contact angle of the TiO₂ thin films was 4°under UV light irradiation for 1h, TiO₂ thin films with 4 layers that annealed at 400℃for 2h show the best photocatalysis,it could decolorate 20.5% MB under UV light irradiation for 2h. The study of preparation of Fe doped TiO₂ film on glass substrate indicated that the addition of Fe in TiO₂ film restrain the growth of TiO₂ grain,the absorption edge of the Fe-doped TiO₂ thin films have red shift,under UV irradiation,the hydrophilicity of lower Fe concentrations doped TiO₂ thin films was better than the undoped TiO₂ thin films. the hydrophilicity of higher Fe concentrations doped TiO₂ thin films was worse than the undoped TiO₂ thin films.The N doped TiO₂ thin films reveal that the addition of N in TiO₂ thin films make the absorption edge red shift.when N:Ti in sol was 2:1,the spectra of TiO₂ thin films shift to visible light range.Under visible light irradiation for 3h the N doped TiO₂ thin that N:Ti in sol was 2:1 and 3:1 show the best hydrophilicity.The N doped TiO₂ thin that N:Ti in sol was 3:1 show the best photo-catalyst.The study of Fe,N co-doped TiO₂ film indicated that the co-doped TiO₂ film can irradiate by visible light, The decrease in water contact angle of co-doped TiO₂ thin films was faster than N doped TiO₂ thin films,the decolorated rate of MB by co-doped TiO₂ thin films was better than N doped TiO₂ thin films.The TiO₂ thin film that the experiment prepared has good hydrophilicity and photocatalytic under ultraviolet and visble light,It provide a solid foundation for pratical application of TiO₂ thin films.