Multifunctional sol-gel xTiO2/(100-x)SiO2 thin films: promising surfaces for self-cleaning applications

Reference Presenter Authors
(Institution)
Abstract
06-029 Gustavo Henrique Magalhães Gomes Jesus, M.A.(Universidade Federal de Minas Gerais); Mohallem, N.D.(Universidade Federal de Minas Gerais); Ferreira, A.M.(Centro Federal de Educação Tecnológica de Minas Gerais); Gomes, G.H.(Universidade Federal de Minas Gerais); Ferlauto, A.S.(Universidade Federal de Minas Gerais); Self-cleaning surfaces are highly required in environmental and energy fields since they prevent the accumulation of dust and reduce the costs of maintenance. The deposition of self-cleaning thin films on glass substrates provides several applications for windows, building facades, windshields, solar cell cover glass, etc. These outdoor applications demand films with good optical quality, superhydrophilicity and superior mechanical properties to ensure a long durability. TiO2/SiO2 thin films are promising candidates to meet all these criteria, because they combine or enhance the properties of both oxides. In this work, xTiO2/(100-x)SiO2 films (x = 0, 20, 40, 60, 80 and 100%) with different numbers of layers (1-5), i.e. thickness, have been obtained by sol-gel dip-coating process. The transmittance, refractive index and thickness of the films were precisely modulated in sol-gel process and assessed by UV-Vis spectroscopy and ellipsometry. xTiO2/(100-x)SiO2 structural models were built with Cauchy model for SiO2, Tauc-Lorentz model for TiO2, and Bruggeman’s EMA theory to combine the properties for TiO2/SiO2. All TiO2/SiO2 films showed anatase phase, which is essential to provide photocatalytic activity and superhydrophilicity. The mixture of TiO2 and SiO2 resulted in the reduction of particle size and RMS roughness, and this reduction was correlated with the enhanced hardness of TiO2/SiO2 films. Superhydrophilic TiO2/SiO2 films with superior mechanical properties were obtained by a stable sol-gel route that makes them suitable for applications as self-cleaning surfaces.
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