Photoactive and self-cleaning TiO2–SiO2 thin films on 316L stainless steel

In this study, TiO2–SiO2 nanocomposite films with different amounts of SiO2 were prepared by sol–gel process and were coated onto stainless steel 316L. The effect of addition of various amount of SiO2 in the precursor solution on the photocatalysis, photo-generated hydrophilicity and self-cleaning property of TiO2 thin films was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, water contact angle measurements and UV spectroscopy. In the tested ranges of SiO2 content and sintering temperature, the highest photocatalytic activity and self-cleaning property were observed in the 15 mol% SiO2 sample sintered at 750 °C. Addition of less than 30 mol% SiO2 had a suppressive effect on the transformation of anatase to rutile and on the crystal growth of anatase in the sintering heat treatment. Phase separation occurred in the composite films for SiO2 content of 30 mol% or more.

► We study the effect of SiO2 addition on the photocatalysis of TiO2 films. ► By adding silica to TiO2, the photocatalysis activity of films can be improved. ► Addition of SiO2 can suppress the transformation of anatase to rutile. ► SiO2 addition prevents the growth of TiO2 grains during the sintering process.