Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 76: Focussed Session: Solid-liquid Interfaces II

O 76.6: Vortrag

Donnerstag, 14. März 2013, 18:00–18:15, H31

Electrochemical activity of Ru(0001) electrodes modified by monolayer Au islands — •Tamara Husch, Otavio Brandao Alves, Albert K. Engstfeld, Sylvain Brimaud, and R. Jürgen Behm — Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany

Bimetallic surfaces where a second metal covers part of a substrate bulk metal, exhibit unique catalytic properties which differ from those of the individual components and possibly also from those of a surface fully covered by a monolayer film of the second metal. The latter was demonstrated for PtML/Ru(0001) [1], where Pt islands act as catalyst for OH and H adsorption on the Ru(0001) substrate.

In this work we investigated whether similar effects can take place also on partly Au monolayer island covered Ru(0001) surfaces, or whether Au monolayers simply leads to blocking of the Ru(0001) surface. Submonolayer Au covered Ru(0001) surfaces were prepared by evaporation at room temperature under ultra high vacuum (UHV) conditions. After determination of the Au coverage by scanning tunneling microscopy (STM), the electrochemical properties of the Au/Ru bimetallic surface were characterized in an electrochemical flow cell attached to the UHV system. Surprisingly, the data show that the charge in the respective adsorption peaks is independent of the the Au coverage, and is always equivalent to a 0.2 ML Au coverage. Possible reasons leading to this unusual behavior are discussed.

[1] H. Hoster, B. Richter, and R.J. Behm, J. Phys. Chem B 108 (2004) 14780.