Natural superhydrophilicity and photocatalytic properties of sol–gel derived ZnTiO3-ilmenite/r-TiO2 films

Abstract

The additive free heteronucleation and nanocrystallization of ternary Zn_xTi_yO_z sols and coatings is presented. A proper adjustment of the Zn/Ti ratio in the sol allows the formation of elaborate superhydrophilic cubic spinel-like Zn₂TiO₄, c-ZnTiO₃ or h-ZnTiO₃-ilmentite/r-TiO₂-rutile films. Their morphology and natural superhydrophilicity can be fine-tuned by the inclusion of 5% silica. This doping step delivers high dye intake capacities and water contact angle values below 3°. XPS analysis indicates that Zn and Si enrichment enables greater surface hydroxylation and thus improved water wetting behaviour. The transparent h-ZnTiO₃-ilmenite/r-TiO₂ nanocomposite coatings deposited on glass and Si-wafers show a remarkable activity in the photomineralization of fatty-acids.