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O: Fachverband Oberflächenphysik

O 64: Focussed Session: Solid-liquid Interfaces I

O 64.4: Vortrag

Donnerstag, 14. März 2013, 11:45–12:00, H31

CO Electroxidation on Pt monolayer island modified Ru(0001) electrodes — •Stephan Beckord, Albert K. Engstfeld, Sylvain Brimaud, and R. Jürgen Behm — Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany

Bimetallic catalysts often show catalytic properties which strongly differ from those of the respective pure components. One example are PtRu catalysts, which are used, e.g., in direct methanol oxidation fuel cells (DMFC) because of their improved tolerance towards CO compared to Pt catalysts. We here report results of a study on the CO oxidation characteristics on structurally well defined PtRu bimetallic surfaces, consisting of a Ru(0001) substrate partly covered by Pt monolayer islands. To elucidate possible correlations between structure and catalytic properties, the Pt coverage was systematically varied. The surfaces were prepared by Pt evaporation under ultra high vacuum (UHV) conditions at elevated temperatures to form hexagonal islands, and characterized structurally by scanning tunneling microscopy (STM). The electrocatalytic CO oxidation was investigated in an electrochemical flow cell attached to the UHV system. In interpreting the resulting data, we take advantage of the result of earlier studies in our group on the gas phase adsorption of CO or hydrogen on similar surfaces [1], and on the electro-adsorption of hydrogen or OH on these surfaces in acid electrolyte [2]. [1] H. Hartmann et al, PCCP 14 (2012) 10919 [2] H. Hoster et al, JPC B 108 (2004) 14780