Photocatalytic Reduction of CO2 in Aqueous Solution on Surface-Fluorinated Anatase TiO2 Nanosheets with Exposed {001} Facets

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• 作者：Zhiqiao He ; Lina Wen ; Da Wang ; Yijun Xue ; Qianwen Lu ; Cuiwei Wu ; Jianmeng Chen ; Shuang Song
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：June 19, 2014
• 年：2014
• 卷：28
• 期：6
• 页码：3982-3993
• 全文大小：675K
• 年卷期：v.28,no.6(June 19, 2014)
• ISSN：1520-5029

文摘

Photocatalytic reduction of carbon dioxide can activate chemically inert carbon dioxide by the use of renewable energy. In the present work, the main products of photocatalytic reduction of CO₂ in aqueous TiO₂ suspensions were found to be methane, methanol, formaldehyde, carbon monoxide, and H₂. Anatase TiO₂ catalysts with various morphologies, such as nanoparticle, nanotube, and nanosheet, were synthesized through a hydrothermal method. The TiO₂ nanosheets were more active than the nanotubes or nanoparticles in the reduction of CO₂ in aqueous solution. This is because the photogenerated carriers prefer to flow to the specific facets. The TiO₂ sheet with high-energy exposed {001} facets facilitates the oxidative dissolution of H₂O with photogenerated holes, leaving more photogenerated electrons available for the reduction of CO₂ on {101} facets. Moreover, surface fluorination promotes the formation of Ti³⁺ species, which is helpful in the reduction of CO₂ to CO₂^{鈥?/sup> and in extending the lifetime of photogenerated electron鈥揾ole pairs. The optimum ratio of exposed {001} to {101} facets for surface-fluorinated TiO₂ nanosheets was found to be 72:28, which corresponds to an initial F/Ti ratio of 1. From our analysis of the effect of adding of known intermediates on the photocatalytic reduction of CO₂, we propose that the photocatalytic reduction of CO₂ with H₂O on surface-fluorinated TiO₂ nanosheets proceeds via a mechanism involving generation of hydrogen radicals and carbon radicals.}