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.