Highly self-cleaning thin films of TiO2-SiO2 co-doped with Ag and F are prepared by the sol-gel method. The asprepared thin films consist of bottom SiO2 and top TiO2 layers which are modified by doping with F, Ag and F-Ag elements. XRD analysis confirms that the prepared thin film is a crystalline anatase phase. UV-vis spectra show that the light absorption of Ag-F-TiO2/SiO2 thin films is tuned in the visible region. The self-cleaning properties of the prepared films are evaluated by a water contact angle measurement under UV light irradiation. The photocatalytic performances of the thin films are studied using methylene blue dye under both UV and visible light irradiation. The Ag-F-TiO2/SiO2 thin films exhibit higher photocatalytic activity under both UV and visible light compared with other samples of pure TiO2, Ag-doped TiO2, and F-doped TiO2 films.

Abstract
 1. Introduction
 2. Experimental
  2.1 Raw materials
  2.2 Preparation of TiO2/SiO2-based thin films
  2.3 Materials characterization
  2.4 Photocatalytic reaction measurement
 3. Results and Discussion
  3.1 XRD analysis
  3.2 Optical properties
  3.3 Morphological properties
  3.4 XPS analysis
  3.5 Photo-induced hydrophilicity
  3.6 Photocatalytic activity
 4. Conclusions
 References

• Byeong-Min Kim(Department of Materials Science and Engineering, University of Seoul)
• Jung-Sik Kim(Department of Materials Science and Engineering, University of Seoul) Corresponding author