Adsorbed Species of CO2 and H2 on Ga2O3 for the Photocatalytic Reduction of CO2

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• 作者：Hideo Tsuneoka ; Kentaro Teramura ; Tetsuya Shishido ; Tsunehiro Tanaka
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：May 20, 2010
• 年：2010
• 卷：114
• 期：19
• 页码：8892-8898
• 全文大小：357K
• 年卷期：v.114,no.19(May 20, 2010)
• ISSN：1932-7455

文摘

Photocatalytic reduction of CO₂ in the presence of H₂ as the reductant was performed over MgO, CaO, ZrO₂, Ga₂O₃, and Al₂O₃. Ga₂O₃ exhibited the highest photocatalytic activity in this process, and CO gas was selectively generated at room temperature and atmospheric pressure. The amount of CO gas evolved depended not only on the amount of CO₂ but also on the amount of H₂ adsorbed on Ga₂O₃. The Fourier transform infrared (FT-IR) spectra showed symmetric CO₃ stretching vibration bands from bidentate and monodentate bicarbonate species in the presence of CO₂ and OH and Ga−H stretching vibration bands in the presence of H₂. The chemisorbed CO₂ species involved in the photocatalytic reduction of CO₂ over Ga₂O₃ was not the bidentate bicarbonate species but the monodentate bicarbonate species. The dissociatively adsorbed hydrogen on Ga₂O₃ reduced the monodentate bicarbonate to the bidentate formate under photoirradiation. The bidentate formate, which was an intermediate in the photocatalytic reduction, decomposed to CO. We propose that photocatalytic reduction of CO₂ over Ga₂O₃ takes place via a Langmuir−Hinshelwood-type mechanism, which is different from the previously reported mechanism for photocatalytic reduction using ZrO₂ or MgO.