Preparation And Properties Of Nanometer TiO₂ Thin Film

TiO₂ nanometer thin film of high photocatalytic activity and hydrophilic activity was prepared via the sol-gel method and the liquid phase reaction under lower temperature. The nanometer film was coated on the ordinary sodium lime glass by dip-coating way, and the morphology and structure of the film was characterized by the scanning electronic microscope (SEM), transmission electronic microscope (TEM), X-ray powder diffraction (XRD) and thermal analysis(DTA-TGA), respectively. The photocatalytic activity, hydrophilic activity, transmittance, resistance to corrosion and the affinity of TiO₂ nanometer to the glass substrate were detected.In the sol-gel method, the particle way used to make colloid . The sol particle was smaller than that made by gather way. By adding of 0.1% N, N-dimethylformamide (DMF),the crack of the surface of the film was reduced, and pattern the film smoothly and perfectly. The photocatalytic activity to the low concentration of methyl orange solution increased with the heating temperature increased, heating time extended and the thickness of the film added. The hydrophilic activity of the film was characterized by the contact angle. The hydrophilic activity increased with the heating temperature increased and heating time extended. Adding 0.1% polyethylene glycol (PEG) enhanced the hydrophilic activity greatly. Increasing the heating temperature and adding 0.1% methyl cellulose (MC)raised the affinity of the film to the substrate material. The transmittance decreased with the thickness of the film added. The film shows high resistance to acid solution and salt solution but low resistance to alkali solution.The anatase TiO₂ sol was prepared via the liquid phase reaction under lower temperature using large quantity of HNO₃ at 70℃. The film by this method was heated at lower temperature, avoiding the high heating temperature treatment in sol-gel method. The photocatalytic activity, hydrophilic activity of the film was high when heating at 220℃. The affinity of the film to the substrate, theresistance to the acid solution, alkali solution and salt solution was good. Through adding different acid and controlling the condition of the reaction process, various micro-structure TiC>2 nano-particles were got. The photocatalytic and hydrophilic activity varied for the film micro-structure difference.Besides, the SiO2/TiO2 nanometer film was prepared to improve not only the affinity of the film to the glass substrate, but also the photocatalytic and hydrophilic activity. It was proved that the photocatalytic and hydrophilic activities change with the molar ratio of the SiO2 / TiC>2. When the molar ratio was 0.1, the phtocatalytic activity was the highest.