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O: Fachverband Oberflächenphysik

O 39: Metal substrates: Solid-liquid interfaces

O 39.10: Talk

Wednesday, March 25, 2009, 17:15–17:30, SCH A315

Influence of anions on dealloying of Cu3Au (111): An in-situ x-ray study — •Aparna Pareek, Genesis Ankah, Sascha Hümann, Michael Rohwerder, and Frank Renner — Max-Planck Institut für Eisenforschung, Max-Planck Strasse 1, 40237 Düsseldorf

Dealloying is a well-known process occurring at the alloy surfaces, which are composed of elements with widely different Nernst potentials. The dealloying behaviour of Cu3Au in 0.1M H2SO4 was previously investigated using electrochemical measurements combined with in-situ X-ray diffraction. We reported the formation of an ultra-thin epitaxial passive Au layer at lower overpotentials with a reversed stacking sequence, which transforms to thicker Au islands at higher overpotentials. Here we investigated the influence of various anionic species (Br, I) dissolved in 0.1M H2SO4 on the above electrochemical corrosion process. Presence of these anionic additives influences the potential where the ultra-thin passive layer transforms to the thicker Au islands. To corroborate the results obtained from X-ray measurements, ex-situ AFM measurements were performed, where the topographical changes with the potential change were recorded. In addition, we present first results of high resolution TEM studies.