Comparison of the Oxidative Activities and Photoelectric Effects for various type of TiO2 Semiconductor Thin Films

• Main Authors: Jing-Feng Lin, 林璟楓
• Other Authors: Chung-Hsuang Hung
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/23104647859705158034

碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程研究所 === 99 === TiO2 assisted photocatalytic oxidation process is a very popular research topic in recent years, especially for the control of many organic pollutants. Many studies have also committed to produce more efficient catalysts for their specific purposes. However, the assessment of the effectiveness and photocatayst activities still is depended on complicated and lengthy chemical testing procedures. Since many photocatalysts are essentially semiconductor metal oxides, the adsorption of pollutants by photocatalysts is the essential step for the accomplishment of photocatalytic oxidation reaction, which will also lead to changing conductivity of the photocatalyst. The major advantage of the conductivity measurement is much faster than conducting chemical experiments. Accordingly, instead of chemical tests, this study aims to develop a rapid screening method for determining photocatalytic activities of the home-made TiO2 thin-film photocatalysts. In this study, a magnetron sputtering technology was applied to preparing thin-film TiO2 photocatalyst on the Al2O3 plate substrates on which comb-type semiconductor thin film circuits has been immobilized. Three organic compounds including MtBE, methanol, and acetone were applied as target organic compounds. Both photocatalytic oxidation activities and the photoelectric effects of the prepared thin film photocataclysts under various experimental parameters including types of pollutants, reaction temperature and water vapor contents were examined for investigating the relationship between photocatalytic activities and electric conductivity of them. The results showed that: the photocatalytic oxidation of MtBE, methanol, acetone, followed typical heterogeneous photocatalytic reactions, following pseudo-first-order reaction kinetics. Water vapor could typical suppress the degradation of the examined organic compounds due to adsorption competition for the active sites on the photocatalysts surfaces between water vapor and organic compounds. On the other hand, more fast decomposition rates were observed in higher temperature conditions. The adsorption of pollutants was proved to be the reaction rate limiting step by simulating the experimental results with a LH kinetics model. The results also demonstrated higher photocatalytic reaction rate of organic compounds with higher adsorption rate but lower “resistance ratio” for the tested photocatalysts. A working temperature range between 60~105 ℃ is suggested for achieving more sensitive results by the prepared thin-film photocatalyst.