Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 58: Surface chemical reactions II
O 58.6: Vortrag
Mittwoch, 24. März 2010, 16:15–16:30, H42
Reactions of Methanol on pseudomorphic Cu/Ru(0001) and O/Cu/Ru(0001) — •Pawel Gazdzicki and Peter Jakob — Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
The adsorption and reactions of methanol on pseudomorphic Cu/Ru(0001) and oxygen precovered Cu/Ru(0001) surfaces have been studied in UHV by IRAS and TDS. In contrast to the clean Cu(111) surface (reversible adsorption), a variety of reaction intermediates have been observed on the laterally expanded Cu/Ru(0001) monolayer. The reaction scheme with perpendicularly oriented methoxy (CH3O) as the most prominent species proceeds very similar to Ru(0001). Interestingly, the Cu monolayer enhances the stability range of methoxy (with respect to decay into CO + 3H) considerably, which is attributed to a lower hydrogen binding energy on Cu/Ru(0001) as compared to Ru(0001).
Inspired by the possibility to enhance the reactivity of Cu(111) by the coadsorption of oxygen, the methanol decomposition has been investigated for Cu/Ru(0001) with preadsorbed oxygen as well. In fact, a completely new reaction pathway could be identified, with the methoxy species being present at 200-350 K and getting oxidized to produce formate (HCOO), as identified by characteristic bands in IRAS in the temperature range 380-460 K. As the dominant desorption product CO2 is detected, which is in contrast to the non-oxidized surfaces which predominantly produce CO and H2.