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Surface Structure and Photocatalytic Activity of Nano-TiO2 Thin Film
Citation:
Wang, Z., E. Sahle-Demessie, A. A. Hassan, AND C. Parrett. Surface Structure and Photocatalytic Activity of Nano-TiO2 Thin Film. JOURNAL OF ENVIRONMENTAL ENGINEERING. American Society of Civil Engineers (ASCE), Reston, VA, 138(9):923-931, (2012).
Impact/Purpose:
We used a single step controlled thin film coating of titanium dioxide (TiO2) on stainless steel surfaces using flame aerosol synthetic technique. The coating was characterized using different techniques. The coated surface has been shown to be an effective surface for environmental applications such as pollutant degradation and other advanced oxidation processses.
Description:
Controlled titanium dioxide (TiO2) thin films were deposited on stainless steel surfaces using flame aerosol synthetic technique, which is a one-step coating process, that doesn’t require further calcination. Solid state characterization of the coatings was conducted by different techniques, including X-ray diffraction spectrum, scanning electron microscopy and atomic force microscopy. The coated thin films were used in a gas phase photoreactor for the partial oxidation of hydrocarbons to alcohols and ketones as an alternative production method for the highly sought oxygenates. For this purpose, oxidation reaction of cyclohexane to form cyclohexanol and cyclohexanone was chosen as a model reaction. The effects of film thickness, anatase-to-rutile ratio and particle morphology on the reactivity of the catalyst were studied. Experimental results revealed that there is an optimal film thickness (between 400 and 700 nm) for the photooxidation process that gives a maximum rate of the oxidation reaction. The yield and selectivity of TiO2 increased with the increase of the film thickness up to 350 – 400 nm. The activity decreased with further increase in thickness. The influence of crystallographic structure of TiO2 on partial oxidation of cyclohexane showed that the catalyst efficiency increased almost linearly with the increase of the anatase fraction between 20 to 95%. The highly porous and soft aggregate TiO2 film morphology tested, showed conversion activity less than the fine particle and transparent thin film.
