Sn4+ or Ce3+ doped TiO2 photocatalytic nanometric films on antireflective nano-SiO2 coated glass

Sn4+ or Ce3+ doped photocatalytic TiO2 nanometric films were prepared by sol–gel method on glass substrates which were first coated with antireflective SiO2 nanometric particles by dip coating. Concentrations of dopants were 1, 2.5 and 5 mol% of TiO2 in the films, and amount of TiO2 in the sols were kept at 0.1 wt%. Prepared coatings were investigated by FESEM and AFM. It was seen from the measurements performed by UV-vis spectrophotometer that SiO2 bottom layer film provided an increase in the light transmittance by 10% points, and that application of TiO2 top layer caused a decrease in the transmittance by 2–4% points. Pencil hardness values of the obtained TiO2 films were in H–3H range. From the performed Rhodamine-B photodegradation tests, both dopants were found to present enhanced photoactivity at a concentration of 1%, and Sn4+ was seen to exhibit a higher activity than that of Ce3+. SiO2–TiO2 nanometric double layer films on glass, functioning for both antireflective and photocatalytic (self-cleaning) purposes were obtained. Loss of light transmittance in dual function films consisting of SiO2–TiO2 nanometric layers could be avoided by keeping TiO2 layer thin; on the other hand photocatalytic activity was improved by doping TiO2 with metal ions.