Enhanced self-cleaning performance of Ag-F-codoped TiO₂/SiO₂ thin films

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.