Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 38: Adsorption an Oberflächen III

O 38.5: Vortrag

Donnerstag, 11. März 2004, 16:45–17:00, H38

Compression of a silver adlayer on Pt single crystal electrode — •Katrin F. Domke, Helmut Baltruschat , and Xaioyin Xaio — Institut für Physikalische Chemie, Abteilung Elektrochemie, Römerstrasse 164, 53117 Bonn

The effect of coadsorption of CO on an underpotentially deposited (UPD) silver monolayer on Pt(111) and Pt(665) single crystals is investigated by means of electrochemical scanning tunneling microscopy (EC-STM) and cyclic voltammetry (CV) in 0.05 M sulfuric acid. Pure electrochemical experiments suggest that coadsorbing CO onto Pt(111) covered by a monolayer of Ag forces Ag atoms of the first UPD monolayer into a second adlayer. The present STM studies reveal the formation of Ag islands on Pt(111) and Pt(665) after coadsorption of CO. These small clusters have a narrow size distribution centered around 10 nm diameter and are of approximately 0.5 nm height. The desorption of the newly formed second Ag UPD, the oxidation of CO, and the desorption of the first Ag UPD can be detected in the corresponding CVs in three different oxidation peaks. STM images recorded afterwards show the unchanged Pt surfaces.