Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 65: Oxides and Insulators

O 65.7: Poster

Mittwoch, 18. März 2015, 18:15–21:00, Poster A

Methanol Adsorption on CeO2(111) Single Crystal Surface — Chengwu Yang, Fabian Bebensee, •Alexei Nefedov, and Christof Woell — Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany

Due to the oxygen mobility and the reducibility of cerium ions, ceria and related materials have extensive catalytic applications [1]. Studying the interaction of methanol with ceria surfaces taking the so-called surface science approach is of crucial importance to gain a fundamental understanding of the oxidation of alcohols to aldehydes [2]. Here, we used a novel apparatus [3] combining a state-of-the-art FT-IR spectrometer with a dedicated UHV-chamber to monitor the adsorption of methanol on CeO2(111) surfaces. The system allows acquiring spectra in both reflection at grazing incidence on single crystals and in transmission geometry on polycrystalline powders. From the comparison to data obtained on well-defined single crystals, a precise interpretation of the complicated infrared spectra for adsorbates on powders can be reached. Methanol adsorbs dissociatively at 120 K at defective CeO2(111) surfaces to yield a surface methoxy species. The IR spectra of this methoxy species, in particular the C-O stretch frequency, provide information about their coordination to the oxide surface and the presence of surface oxygen vacancies.

[1] A. Trovarelli, P. Fornasiero (Ed.), Catalysis by Ceria and Related Materials (2nd edition), Imperial College Press, London, 2013.

[2] J. M. Vohs, Chemical Reviews, 2013, 113, 4136.

[3] C. Yang, et al., Phys. Chem. Chem. Phys, 2014, 16, 24165.