Photocatalytic activity, hydrophilic and optical properties of nanocrystalline titania thin films prepared by sol-gel dip coating

ABSTRACTNanocrystalline anatase titania thin films were prepared by using two different precursor solutions, a highly acid solution (Sol-1) and a polymer-like solution (Sol-2), via the dip-coating technique on different substrates (<100>-Si wafer, fused silica and soda lime glass). The influence of the two sol-gel titania precursor solutions and of the substrate type on the film morphology, coating porosity, surface roughness, crystalline phases and grain size of the titania films were investigated. Our experimental results clearly indicate that the sol - composition and substrate type remarkably influence the microstructural/morphological properties of the titanium dioxide. They consequently modify the optical response and hydrophilic performances of the samples. The photocatalytic oxidations of the methylene blue in water of the samples grown on the glass substrate were monitored to investigate the influence of the sol-gel precursor solution on the photocatalytic activity of the titania coatings, and the results were put in relation with the hydrophilic and optical properties of the films. The outcome demonstrates that the optical properties and the hydrophilic and photocatalytic performances of nanocrystalline titania can be opportunely tailored tuning the size dimension of the crystalline domain according to the specific coating applications.