Regensburg 2004 – scientific programme

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O: Oberflächenphysik

O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)

O 28.56: Poster

Wednesday, March 10, 2004, 16:00–19:00, Bereich C

Methanol oxidation on clean and oxygen-covered copper surfaces — •Sung Sakong and Axel Groß — Physik-Department T30, Technische Universität München, 85747 Garching, Germany

We have studied methanol oxidation steps over clean and oxygen-covered copper surfaces by density functional theory (DFT) calculations. The reaction pathways are determined by the nudged elastic band (NEB) method [1] which in particularly also yields the intermediate states and the reaction barriers. We find that on clean copper surfaces, methanol is only weakly bound. The decomposition into methoxy and hydrogen is activated. Upon heating, methanol rather desorbs than dissociates. The further decomposition of adsorbed methoxy into formaldehyde and hydrogen is hindered by large barriers (≥ 1.5eV).

The surface intermediate states in the methanol oxidation are significantly stabilised by co-adsorbed oxygen. The DFT calculations show that on oxygen-covered Cu(110), methanol dissociates spontaneously because of the strong attraction between the methanol hydroxyl hydrogen and the surface oxygen. The reaction steps are analysed in terms of the underlying electronic structure. Our calculations confirm the importance of co-exposed oxygen in the methanol oxidation on copper surfaces found in experiments (see, e.g., [2]).

[1] G. Henkelman and H. Jónsson, J. Chem. Phys. 113, 9978 (2000).

[2] Ch. Ammon et al., Surf. Sci. 507, 845 (2002).