Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 12: Metal substrates: Adsorption of O / H and inorganic molecules I
O 12.3: Vortrag
Montag, 14. März 2011, 15:30–15:45, WIL A317
Coadsorption of CO and hydrogen on submonolayer Pt/Ru(0001) films — •Heinrich Hartmann, Thomas Diemant, Joachim Bansmann, and R. Juergen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany
Due to their high CO tolerance, bimetallic Pt-Ru catalysts are an attractive electrode material for the oxidation of H2-rich fuel gases prepared by reforming of fossil fuels in low-temperature polymer electrolyte fuel cells. This makes the adsorption properties of PtRu systems an interesting topic for fundamental studies on model systems.
We have investigated the coadsorption of CO and hydrogen on submonolayer Pt films deposited on the Ru(0001) surface with TPD and IRAS under UHV conditions. Adsorption of either of the two molecules on the Pt covered parts of the bimetallic surface is weaker compared to adsorption on the remaining uncovered Ru parts. Coadsorption of hydrogen and CO leads to a displacement of hydrogen from the Ru areas to the energetically less favourable Pt islands. At the same time a further weakening of the hydrogen-Pt bond is observed, which is attributed to repulsive interactions between adsorbed hydrogen and CO molecules.