Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 64: Metal substrates: Adsorption of inorganic molecules

O 64.2: Talk

Friday, March 27, 2009, 11:30–11:45, SCH A215

Coadsorption of CO and hydrogen on PtRu/Ru(0001) surface alloys — •Thomas Diemant¹, Joachim Bansmann¹, Hubert Rauscher^1,2, and R. Juergen Behm¹ — ¹Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany — ²Institute for Health and Consumer Protection, Joint Research Centre, European Commission, I-21020 Ispra (VA), Italy

Due to their superior CO tolerance, bimetallic platinum-ruthenium catalysts are one of the most promising materials for the anodic hydrogen oxidation reaction in low-temperature polymer electrolyte fuel cells in the presence of small CO amounts. Therefore, the study of the adsorption properties of PtRu systems is of high interest. We have investigated the coadsorption of CO and hydrogen on PtRu/Ru(0001) surface alloy model systems by TPD and IR spectroscopy under UHV conditions. While hydrogen adsorption on the bimetallic surface alloys is already weakened in the absence of CO compared to the case of unmodified Ru(0001) [1], the addition of CO to the surface leads to a further significant weakening of hydrogen adsorption, caused by the repulsive interaction between the adsorbed species. Furthermore, post-adsorbed CO displaces hydrogen to energetically less favourable Pt-rich adsorption sites. The implications of our results for fuel cell applications will be discussed.

[1] T. Diemant et al., J. Phys. Chem. C 112 (2008) 8381.