Preparation and characterization of SiO2–TiO2 neutral sol by peroxo sol–gel method and its application on photocatalytic degradation

A bifunctional SiO2–TiO2 material for antireflection and photocatalytic degradation was prepared by peroxo sol–gel method. The as-prepared sols have the following unique properties: (1) they can contain crystalline anatase nanoparticles without subsequent calcinations process and (2) they are very stable even without the presence of any protecting surfactant (i.e., no aggregation even after 1 year). The particle size of TiO2 decreased as the SiO2 content increased. The aspect ratio of TiO2 particle also increased with increasing SiO2 content. The SiO2–TiO2 sol was neutral or slightly basic. SiO2–TiO2 sol prepared by the presenting peroxo sol–gel method possesses several advantages, i.e., small TiO2 particles in nanometer scale, high aspect ratio of TiO2, the lack of need for any surfactant, non-acidity and the lack of need for any annealing processes. The as-prepared sol can be used as a coating precursor on any substrate, and SiO2–TiO2 films were successfully coated on glass substrates by dip-coating method. The as-deposited films were subjected to drying at 80 °C in air. The transmittance of the SiO2–TiO2-coated glass increased by 4 %, as compared to the bare glass. Photocatalytic degradation of methylene blue in water was carried out under UVA (365 nm) and UVC (254 nm) irradiation with the presence of the SiO2–TiO2 films as catalysts. The results showed that the presence of SiO2 in TiO2 films would improve the photocatalytic activity, as compared to bare TiO2 film. In addition, the fabricated SiO2–TiO2 films showed high anti-reflection and high photocatalytic activity than bare TiO2 films.