Effect of Photoexcited Electron Dynamics on Photocatalytic Efficiency of Bismuth Tungstate

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• 作者：Fumiaki Amano ; Akira Yamakata ; Kohei Nogami ; Masatoshi Osawa ; Bunsho Ohtani
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：August 25, 2011
• 年：2011
• 卷：115
• 期：33
• 页码：16598-16605
• 全文大小：920K
• 年卷期：v.115,no.33(August 25, 2011)
• ISSN：1932-7455

文摘

Photoexcited carrier dynamics of bismuth tungstate (Bi₂WO₆) photocatalysts was investigated by time-resolved infrared (IR) absorption spectroscopy. Monotonic absorption at the mid-IR region, which is attributable to absorption by photoexcited electrons, was monitored as a function of time delay from the microsecond to millisecond range after photoexcitation. Bi₂WO₆ particles with different crystalline content were prepared by hydrothermal reaction at several temperatures and used to elucidate the relation between density of photoexcited carriers and steady-state photocatalytic efficiency. Photocatalytic efficiency was tested using two reactions: oxidative decomposition of acetic acid in an aqueous solution (reaction 1) and oxidative decomposition of acetaldehyde in air (reaction 2). Crystallization of Bi₂WO₆ particles suppressed the fast recombination of photoexcited electrons and holes within 1 渭s. In the case of crystallized particles, the density of the photoexcited electron increased with an increase in the crystalline content, and the photocatalytic efficiency for reaction 1 strongly depended on the crystalline content, indicating that photoexcited electrons remaining in the submillisecond time range significantly affect the reaction rate. On the other hand, photocatalytic efficiency for reaction 2 showed a proportional relation with specific surface area rather than crystalline content. The difference in a decisive factor depending on reaction condition is considered to be the slower rate of reaction of photoexcited electrons with molecular oxygen, which might occur within a time range between 200 渭s and 3 ms over Bi₂WO₆.