Effect of ZnO on a Superhydrophilic Self-Cleaning Properties of TiO₂/SiO₂ Thin Film on Glass Slide Substrate

Abstract:

This work aims to study the effect of ZnO containing in TiO₂/SiO₂ film on the superhydrophilic property after exposed to different types of light. The metal solutions were prepared by sol-gel technique and the film was deposited on glass slides by dip coating method. The parameter studied was the amount of ZnO in the TiO₂/SiO₂ film. The contents of ZnO were 5-20% weight (increased by 5%). The amount of TiO₂ was constant at 30% weight. The obtained films were analyzed for their roughness. The results indicated that film roughness changed according to the ZnO contents. With 5%ZnO in the thin film, the roughness was 0.726 nm while 20%ZnO obtained the roughness of 2.128 nm. UV-Vis spectrophotometer was used for measuring of transmittance of films. At wavelength of 550 nm, the transmittances of each film were greater than 90%. Band gap energy of each film was calculated from the transmittance data. It was found that the average band gap energy of the films was 2.47 eV. Then, the films contained various amount of ZnO were grouped into 2 sets. The first set was exposed to visible light while the other set was exposed to UV. The duration of exposure was 5 hr. Both sets of films after exposed to any light were kept in a black box controlled relative humidity of 85%. Each film was measured contact angle every day. It was found that the 30%TiO₂/5%Zn/SiO₂ film exposed to visible light showed the best superhydrophilic property. The contact angle was about 0-5° within 3 days. This may due to the reduction of band gap energy in the presence of ZnO in TiO₂/SiO₂ films to 2.41 eV and the roughness of the film.

• Periodical: Advanced Materials Research (Volume 1131)
• Pages: 237-241
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1131.237
• Online since: December 2015
• Authors: Akkarat Wongkaew*, Chanida Soontornkallapaki, Naritsara Amhae, Wichet Lamai
• Keywords: Band Gap Energy, Mixed Oxide Film, Sol-Gel, Superhydrophilicity, Visible Light, ZNO

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