Hydrophilic and Photocatalytic Performances of Y-Doped Titanium Dioxide Thin Films

Abstract

Pure and Y-doped TiO2 thin films are prepared on glass by sol-gel method. Tetrabutyl titanate was used as Ti precursors. The chemical composition, structure and properties of TiO2 thin films are characterized by XRD, FT-IR, UV-Vis and Optical Contact Angle Measuring Instrument. Their photocatalytic performances were studied in detail by the methylene blue degradation model. The results show that the crystalline phase of Y2Ti2O7 is formed and the phase transformation from anatase to rutile is restrained when Y is doped in the TiO2 thin films. However, with the continuous increase in calcination temperature, its photocatalytic activity decreases, because the anatase will transform to the rutile. The proper amount of Y doping will cause the lattice to expand, the new defects will form and the smaller band-gap energy will be revealed. Thus, the absorption ability toward the ultraviolet can be improved, the redshift of the absorption band can also be found. As the results of it, the hydrophilicity and photocatalytic efficiency can improved. Furthermore, the photocatalytic activity increases with the hydrophilicity. When the calcination temperature of thin films is 450oC and the Y-doping is 0.3%, the main crystalline phase of the samples is the anatase, the contact angle is only 13.7o and the degradation ratio of methylene blue reached 98.84%.