Characteristics modification of TiO₂ thin films by doping with silica and alumina for self-cleaning application

Abstract

Self-cleaning hydrophilic and hydrophobic properties of TiO₂-based thin films on glass substrates have been investigated in this study. The addition of SiO₂ into TiO₂ can increase the wettability of films and maintain the hydrophilic state for a long time even in the dark. The contact angle of water on deposited films containing 15% SiO₂ is less than 2° after 2 h of UV illumination. These TiO₂–SiO₂ films exhibit excellent antifogging characteristics. Meanwhile, TiO₂–Al₂O₃ films possess high water repellent ability and the photo-induced self-cleaning can take place even in visible light. The TiO₂ thin film containing 33% of Al₂O₃ shows a high hydrophobic state with a water contact angle of 73° after being irradiated with sunlight for 2 h. A comparison of hydrophilic TiO₂–SiO₂ and hydrophobic TiO₂–Al₂O₃ films demonstrates the ability to modify the TiO₂ thin film properties for self-cleaning applications.

Keywords:

• TiO2
• hydrophilic
• hydrophobic
• modification capability

Acknowledgements

The authors highly appreciate the financial support of the Department of Science and Technology, Ho Chi Minh City, Vietnam.