Influence Of Additives On Sol-Gel Nanoporous TiO2 Thin Film

Choong, Mei Teng (2015) Influence Of Additives On Sol-Gel Nanoporous TiO2 Thin Film. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

Titanium Dioxide (TiO2) sol was prepared at room temperature, approximately 27 ˚C and ambient pressure by hydrolysis of Titanium Tetraisopropoxide (TTiP) in acidic aqueous solution (Hydrochloric acid, HCl), ethanol (C2H6O) and distilled water. Additives were added into TiO2 sol as it can enhanced in the photocatalytic performance by changing the microstructure of the TiO2 thin film formed. Polyethylene glycol (PEG) and Degussa P25 were the additives used in this study. PEG can promote the formation of crack free and nanoporous TiO2 thin film. Besides, Degussa P25 powder was used to increase the anatase phase presence in the crystalline phase as it consists of a combination phases of anatase and rutile phases with the ratio of 70:30. The TiO2 thin films are deposited on microscope glass slides from the as-prepared TiO2 sol by a dip coating process at room temperature and ambient pressure. TiO2 layers on the substrate were thickened by 5 consecutive coatings. Heat treatment was applied at a higher temperature at 500 ˚C to improve crystallization. Eventually, TiO2 thin film was found to be in well adhesion through the substrates. Scanning electron microscope (SEM) investigations revealed that substrates coated with TiO2 and TiO2/PEG exhibited same surface morphology; both formed coating with severe cracks and some white precipitates. However, amount of cracks were observed to be reduced in TiO2/PEG coating compared to TiO2 coating because PEG tend to inhibit the growth of cracks. TiO2/Degussa P25 formed a denser structure coating which was free of crack and P25 nanoparticles tend to agglomerates on the final coating. Fine pores with estimated size of 2 μm were formed also. These are the characteristics that are proned to achieve high photocatalytic performance.

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