Photocatalytic Oxidation of Nitrogen Dioxide with TiO2 Thin Films under Continuous UV-Light Illumination

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• 作者：Yoshihisa Ohko ; Yuri Nakamura ; Akari Fukuda ; Sadao Matsuzawa ; Koji Takeuchi
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：July 17, 2008
• 年：2008
• 卷：112
• 期：28
• 页码：10502 - 10508
• 全文大小：1175K
• 年卷期：v.112,no.28(July 17, 2008)
• ISSN：1932-7455

文摘

A deactivating behavior of TiO₂ photocatalysts in NO₂ oxidation to HNO₃ was studied with use of TiO₂ nanoparticulate thin films (0.5−1.5 μm thick) under UV light illumination over 10 h. The photocatalytic activity was decreased with accumulation of HNO₃ on the TiO₂ surface. For thicker TiO₂ films, the deactivation rate was found to be slower. The amount of HNO₃ trapped on the TiO₂ surface was increased and finally saturated, at which the largest amount of HNO₃ was proportional to the thickness of the film. On the basis of the results, we concluded that the produced HNO₃, inhibiting the reaction as a physical barrier, must be able to diffuse on the TiO₂ surface at a rate of at least more than 1.5 μm h⁻¹, and finally distributes homogeneously on the whole film. The maximum density of HNO₃ accumulated on the TiO₂ surface was estimated to be ~2 molecules nm⁻² under standard conditions. Finally, when the steady state is reached, the photocatalytic activity remained ~8% of the initial one.