INFLUENCE OF TIO₂ SOL-GEL FORMULATION ON MICROSTRUCTURE AND PHOTOCATALYTIC EFFICIENCY OF CERAMIC TILE COATINGS

Abstract

The microstructure and crystalline formation of TiO₂ coatings play a decisive role in determining their photocatalytic performance. This study investigates how varying TiO₂ formulations, particularly the incorporation of a commercially available TiO₂ nanopowder (such as Degussa P25), influence the properties of TiO₂ coatings deposited on unglazed ceramic tiles (Ra = 5.50 ± 0.2 μm) via sol–gel dip coating. All coatings were heat-treated at 500 °C, characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), and evaluated for methylene blue (MB) degradation under ultra-violet (UV) light following ISO 10678:2010. Adding TiO₂ nanopowder markedly modified coating morphology, enabling the formation of continuous, homogeneous nanocomposite layers comprising a TiO₂ matrix binding well-dispersed TiO₂ nanoparticles. This resulted in anatase–rutile phase coexistence, improved adhesion, and reduced cracking, while only modestly increasing overall crystallinity. The TTiP–P25 (50 g/L) formulation exhibited the highest specific photocatalytic activities of 4.74 × 10⁻⁵ ± 1.0 × 10⁻⁶ for glass slides and 2.99 × 10⁻⁵ ± 1.8 × 10⁻⁶ for ceramic tiles; surpassing all other formulations. These findings highlight a scalable route to high-performance TiO₂ nanocomposite coatings for durable, self-cleaning building materials.