IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Electrochemistry and Fluid-Solid Interfaces Monday Sessions
       Session EC-MoP

Paper EC-MoP3
Microscopic Structure and Reactivity of Alloyed AuPd(111) Electrode Surfaces

Monday, October 29, 2001, 5:30 pm, Room 134/135

Session: Poster Session
Presenter: R.J. Behm, University Ulm, Germany
Authors: F. Maroun, Universite P & M Curie, France
F. Ozanam, CNRS-Ecole Polytechnique, France
O. Magnussen, University Ulm, Germany
R.J. Behm, University Ulm, Germany
Correspondent: Click to Email
The electrochemical and electrocatalytic properties of defined atomic Pd ensembles in a PdAu(111) surface alloy electrode, serving as model system for bimetallic electrocatalyts, were evaluated by a combination of in-situ microscopic, IR spectroscopic and electrochemical measurements, using H and CO adsorption/ oxidation as model reactions. PdAu electrodes with atomically flat surfaces and variable stoichiometry were prepared in a controlled way by electrodeposition on Au(111) under diffusion-limited conditions. The amount and distribution of Pd surface atoms was determined by atomic resolution in-situ scanning tunneling microscopy with chemical contrast. The electrochemical/catalytic properties of individual types of Pd ensembles were determined by comparison with spectroscopic and voltammetric data. This way, the critical ensembles for CO and H adsorption were identified as Pd monomers and dimers, respectively. The specific chemical properties of these ensembles as compared to bulk Pd and Pd thin-film electrodes provide a microscopic basis for understanding the distinct catalytic properties of PdAu alloys observed at the macroscopic scale.