Superhydrophilicity and photocatalytic property of nanocrystalline titania sol-gel films

Nanocrystalline titania thin films were prepared by deposition and annealing of titania sol-gel precursor materials, both non-hydrated solutions and hydrosols. The sol-gels were immobilized on glass substrates applying doctor blade and dip-coating deposition techniques. The nanoparticle size, determined by the full-width at half-maximum of the X-ray diffraction peaks as well as by shifting and broadening of the Raman modes, strongly depends on the precursor solution. Significant differences were also confirmed on the surface characteristics, roughness and complexity of the films by atomic force microscopy. The films present high activity towards photodecomposition of methyl orange azo-dye together with enhanced photo-induced superhydrophilicity under illumination with ultraviolet light. Judicious choice of the precursor material and efficient control of the deposition parameters may lead to the optimization of their photocatalytic and/or superhydrophilic properties. (c) 2007 Elsevier B.V. All rights reserved.