Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Metal Substrates: Adsorption of Inorganic Molecules
O 62.10: Vortrag
Donnerstag, 28. Februar 2008, 11:45–12:00, MA 042
CO adsorption on bimetallic AuxPt1−x surface alloys studied by TPD and IRAS — •Menhild Eyrich, Heinrich Hartmann, Thomas Diemant, Andreas Bergbreiter, Harry Hoster, Joachim Bansmann, and Rolf Juergen Behm — Institute of Surface Chemisty and Catalysis, Ulm University, D-89069 Ulm, Germany
The interaction of CO with bimetallic AuxPt1−x surface alloys supported on Pt(111) is investigated by temperature programmed desorption and infrared reflection absorption spectroscopy to study the influence of the Au content on the chemical properties of the surface alloys. The surface composition and the distribution of surface atoms were determined by scanning tunnelling microscopy, showing a tendency for the segregation of both metals on the surface. Due to the preference for the formation of homo-atomic domains, the adsorption of CO on the Pt part of the surface alloys is only weakly affected up to very high Au concentrations and very similar to the pristine Pt(111). This behaviour is manifested in an almost constant initial CO desorption energy and the successive occupation of on-top and bridged adsorption sites with increasing CO coverage. Since the adsorption of CO is not possible on the Au part of the surface alloys under the conditions of this study, a decrease of the CO saturation coverage and of the initial sticking coefficient are observed with increasing Au content.