The preparation and chemical structure of TiO2 film photocatalysts supported on stainless steel substrates via the sol–gel method

A compact TiO2 film with a thickness of about 90 nm has been coated onto stainless steel substrates by using the sol–gel method with Ti(OBu)4 as precursor. AES analysis showed that Fe diffused from the substrate into the TiO2 film and reacted with O2 from the air, resulting in the formation of an interlayer of iron oxide during the annealing process. XPS and XRD results indicate that the Fe in the TiO2 layer and interlayer exists as a rhombohedral Fe2O3 species. With increasing annealing temperature and time, the diffusion can be significantly promoted. Although iron oxide did not react with TiO2 film, the formation of anatase TiO2 film was impeded due to the presence of Fe. It has been proven by UV spectroscopic analysis of TiO2 film that Fe enters the TiO2 lattice and changes the lattice parameters, resulting in a change in the optical properties of the TiO2 film photocatalyst.