Synthesis, characterization and demonstration of self-cleaning TiO₂ coatings on glass and glazed ceramic tiles

Abstract

An effort was made not only to demonstrate the performance of the self-cleaning coatings on building materials such as ceramic glazed tiles and glass windows, but also to understand the fundamental issues that are still alive in the field of self-cleaning surfaces based on photocatalysis. Nano TiO₂ transparent thin films were generated by dip, spray and flow coating method. The present results indicate that the inconsistent results in the self-cleaning studies may be due to the effect of aggregation of model pollutant (methylene blue) dye on TiO₂ surface. The effect of aliovalent metal ion (Ni²⁺, Fe³⁺, Nb⁵⁺) doping on phase formation, polymorphic transition, visible light absorbance and optical transparency of TiO₂ film were investigated using X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and UV visible absorption spectroscopy. The improved visible light activity of doped TiO₂ thin film was correlated to the Ti(Ni/Fe)O₃ phase formation, UV and visible light absorbance, variation in the optical energy band gap and the probable light scattering associated with grain size.