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O: Oberflächenphysik

O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)

O 14.18: Poster

Montag, 8. März 2004, 18:00–21:00, Bereich C

Step Decoration of Gold Single Crystal Electrode Surfaces with Pd — •Fernando Hernandez Ramirez and Michael Nielinger — Institut fuer physikalische u. theor. Chemie, Universitaet Bonn, Roemerstrasse 164, 53117 Bonn, Germany

Surfaces of regularly stepped single crystals can be decorated with foreign metals in order to change their physicochemical properties.

Step decoration of vicinally stepped platinum single crystals was achieved for many metals and can be easily monitored in cyclic voltammetry due to the suppression of the corresponding hydrogen adsorption at step sites. By using the system Au(hkl)/Pd reactive bonding sites shall be introduced at regular spacings. Here step decoration is more difficult to prove. Cyclic voltammetry shows two Pd-oxidation peaks, the first one being almost independent of Pd coverage. Hydrogen adsorption on the modified stepped surfaces, but not on Au(111)/Pd, takes place only when more than a critical amount of Pd, corresponding to a monoatomic row of Pd at step sites, has been deposited. These facts support the assumption of step decoration and show that hydrogen only adsorbs at 3-fold hollow sites of Pd.