CO2 Adsorption As a Flat-Lying, Tridentate Carbonate on CeO2(100)

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• 作者：Peter M. Albrecht ; De-en Jiang ; David R. Mullins
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 1, 2014
• 年：2014
• 卷：118
• 期：17
• 页码：9042-9050
• 全文大小：441K
• 年卷期：v.118,no.17(May 1, 2014)
• ISSN：1932-7455

文摘

Results of an experimental and computational study of CO₂ adsorption onto a CeO_X(100) thin-film surface are reported. For both oxidized CeO₂(100) and reduced CeO_1.7(100), a 5 L dose of CO₂ at 180 K resulted in mainly carbonate ([CO₃]^{2鈥?/sup>) on the surface with a minute amount of physisorbed CO₂ that desorbed by 250 K based on C 1s and O 1s photoemission and C k-edge NEXAFS. No evidence for the formation of a carboxylate intermediate was indicated. Angle-dependent C k-edge NEXAFS revealed that the carbonate species was oriented parallel to the surface suggesting a tridentate configuration. Various adsorption geometries were tested using DFT PBE+U calculations. The most stable configuration was a carbonate with its molecular plane parallel to the surface and each O atom bonded to two Ce cations. Through temperature-programmed desorption (TPD), it was determined that CO₂ was the sole reaction product. CO was not detected in the TPD for the reduced surface, indicating that reoxidation of a reduced CeO_2-X(100) surface by CO₂ did not occur. TPD and photoemission indicated that the coverage and the thermal stability of the [CO₃]2鈥?/sup> intermediate were greater on partially reduced CeO_1.7(100) compared to CeO₂(100).}