Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 82: Metal Substrates II
O 82.10: Vortrag
Donnerstag, 3. April 2014, 18:15–18:30, WIL A317
The CO adsorption on Ru(0001) and bimetallic PtRu/Ru(0001) surfaces at elevated pressures (from 10−3 to 100 mbar) — •Thomas Diemant, Joachim Bansmann, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany
PtRu catalysts are, due to their superior CO tolerance, a promising material for the anodic hydrogen oxidation reaction in low-temperature polymer electrolyte fuel cells in the presence of small amounts of CO. After studying the adsorption of CO and hydrogen on structurally well-defined PtRu/Ru(0001) surfaces under UHV conditions, we extended our studies to catalytically relevant conditions (atmospheric pressure and RT), investigating the CO adsorption on Ru(0001) and bimetallic surfaces at elevated CO pressure, using polarization-modulated IR reflection absorption spectroscopy (PM-IRAS).
On unmodified Ru(0001), we find a gradual blue-shift of the peak position with increasing pressure, which stops at a wave number higher than the value found for UHV CO saturation. In agreement with a recent XPS study on this topic [1], we explain this finding by a higher CO saturation coverage than obtained under UHV conditions. For CO adsorption on a Pt/Ru(0001), we find a comparable wave number. In this case, however, it resembles the value obtained for UHV adsorption at 150 K, supporting our previous model of a kinetic barrier for direct CO adsorption on Ru(0001) at high CO coverages, which can be circumvented by spillover from Pt monolayer islands.
[1] D. E. Starr, H. Bluhm, Surf. Sci. 608 (2013) 241.