Preparation of Glass Plate-Supported Ag Doped Nanostructure TiO2 Composite Films Deposited by Sol-Gel Spin-Coating Technique and Photocatalytic Degradation to Methyl Orange

Titanium dioxide has attracted significant attention of researchers because of many interesting physical and chemical properties. Due to the large surface area, thin and composite coatings consisting of anatase TiO2 nanoparticles show high photocatalytic efficiency. Sol–gel derived titanium dioxide composites have been also developed and investigated for the purpose of producing thin and composite films and self-supported photocatalysts. The resulting photocatalysts exhibit relatively high surface area and enhanced mechanical stability and integrity [1,2]. The only drawback of TiO2 is that its band gap lies in the near-UV of the electromagnetic spectrum. As a consequence, only UV light is able to create electron–hole pairs and to initiate the photocatalytic processes. Electrons in the valence band of TiO2 are excited to the conduction band, with formation of holes in the valence band. At the same time electrons of Ag nanoparticles, when irradiated with the light of their plasmon resonance wavelength, are excited and transformed to adsorbed oxygen with formation of O2−. The Ag nanoparticles are consequently oxidized by O2− to colourless Ag+ ions [3]. In presence of TiO2 these Ag+ ions are reduced by the excited electrons and Ag nanoparticles are reformed.The purpose of this study is to obtain insights on how the incorporation of Ag into the modified titania composite films affects the photocatalytic activity of such macroporous films, so as to design high performance TiO2 composite films for water treatment