Comparison of optical and photocatalytic properties of TiO2 thin films prepared by electron-beam evaporation and sol-gel dip-coating

Transparent TiO2 thin films were deposited on soda lime glass by electron-beam evaporation (EBE) and sol-gel dip-coating (SGD) methods. Optical and photocatalytic properties of the EBE and SGD films were compared. The transmittance of both films decreased with increasing calcination temperature from 300 to 500 degreesC as a result of the growth of particles. The refractive index of the SGD films increased significantly from 1.79 to 1.93 after heating at 500 degreesC, whereas that of the EBE films increased slightly from 2.09 to 2.13. The EBE films had better optical property than the SGD films. On the other hand, the SGD films exhibited much better photoactivity than the EBE films. This has been explained in terms of porosity and the formation of Ti3+ ions during calcination. (C) 2003 Elsevier Science B.V. All rights reserved.