二氧化铈（110）表面二氧化碳吸附的X射线光电子能谱和近边X射线吸收精细结构研究

Carbon Dioxide Adsorption on CeO (110): An XPS and NEXAFS Study.

作者信息

Yang Chengwu, Bebensee Fabian, Chen Jun, Yu Xiaojuan, Nefedov Alexei, Wöll Christof

机构信息

Institute of Functional Interfaces, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.

China Academy of Engineering Physics, Mianshan Road 64, 621900, Mianyang, China.

出版信息

Chemphyschem. 2017 Jul 19;18(14):1874-1880. doi: 10.1002/cphc.201700240. Epub 2017 May 19.

DOI:10.1002/cphc.201700240

PMID:28472552

Abstract

The adsorption of CO on the surface of a CeO (110) bulk single crystal was studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The high-quality XPS and C K-edge NEXAFS data show that CO adsorbs as a carbonate species on both fully oxidized CeO (110) and partially reduced CeO (110). No evidence for the formation of a carboxylate (CO ) intermediate could be found. On the fully oxidized CeO (110) substrate, the carbonate decomposes upon heating to above 400 K, leading to the desorption of CO . The NEXAFS data reveal the presence of a minor amount of formate (or carboxylate) and bicarbonate species, which are related to reactions of CO with surface hydroxyl groups. In the case of reduced CeO (110), the carbonate species completely disappear upon heating to temperatures above 500 K. In contrast to conclusions presented in earlier works, the oxidation state of the surface is unchanged, that is, CO does not re-oxidize the reduced CeO (110) surface.

摘要

采用X射线光电子能谱（XPS）和近边X射线吸收精细结构（NEXAFS）光谱研究了CO在CeO（110）体相单晶表面的吸附情况。高质量的XPS和C K边NEXAFS数据表明，CO在完全氧化的CeO（110）和部分还原的CeO（110）上均以碳酸盐物种的形式吸附。未发现形成羧酸盐（CO）中间体的证据。在完全氧化的CeO（110）衬底上，碳酸盐在加热至400 K以上时分解，导致CO脱附。NEXAFS数据揭示了少量甲酸盐（或羧酸盐）和碳酸氢盐物种的存在，它们与CO与表面羟基的反应有关。在还原的CeO（110）情况下，碳酸盐物种在加热至500 K以上时完全消失。与早期工作中给出的结论相反，表面的氧化态未发生变化，即CO不会使还原的CeO（110）表面再氧化。