Preparation of Si-TiO₂ Films and Their Properties of Photogenerated Cathodic Protection

Si-TiO₂ films were fabricated on the surface of 304 stainless steel by sol-gel method and dip-coating technology. The morphology and crystalline phase of Si-TiO₂ films were observed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). And the effects of sintering method, sintering temperature and film thickness on Si-TiO₂ films were analyzed. UV-vis absorption spectroscopy, fluorescence spectroscopy and photoelectrochemical response curve were used respectively to evaluate the photoelectric response characteristics of Si-TiO₂ film and its performance of photogenerated cathodic protection. The results showed that the three-layer Si-TiO₂ films prepared by layer-by-layer sintering at 500℃ had the best optoelectronic properties. Doping of Si enhanced the absorption intensity of UV light and inhibited the recombination of electron and hole, thus, produced more photoelectrons, which enhanced the protection performance for substrate materials of 304SS. The Si-TiO₂ films under UV light illumination made the electrode potential of 304SS shift to -650 mV(SCE), and provided cathodic protection for 304SS.