Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 59: Poster Session II (Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: arrays; Nanostructures at surfaces: Wires, tubes; Nanostructures at surfaces: Other; Plasmonics and nanooptics; Metal substrates: Epitaxy and growth; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsoprtion of organic / bio molecules; Metal substrates: Adsoprtion of inorganic molecules; Metal substrates: Adsoprtion of O and/or H; Metal substrates: Clean surfaces; Density functional theory and beyond for real materials)

O 59.64: Poster

Wednesday, March 24, 2010, 17:45–20:30, Poster B1

Dealloying below the critical potential: Cu-Au and Cu-Pd — Frank Uwe Renner, •Shilan Meimandi, and Aparna Pareek — MPI Eisenforschung, Düsseldorf

Corrosion causes a loss of more than 3% of GDP to society. Dealloying is an important corrosion process occurring at alloy surfaces immersed in electrolyte, and which are composed of elements with a large difference in Nernst potentials. The dealloying behaviour of the model system Cu3Au in 0.1M H2SO4 was previously investigated using in-situ X-ray diffraction [1] and we will present here recent ex-situ measurements using scanning Auger electron spectroscopy with a lateral resolution of less than 10 nm. 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 and finally to porous Au at higher overpotentials (critical potential for dealloying). For the in-situ X-ray diffraction studies we developed recently an UHV compatible electrochemical chamber in order to study more reactive samples and electrolytes which we recently adapted for use with ionic liquids as electrolytes [2]. The research on dealloying is now extended to the system of Cu-Pd alloys and we will present first results by in-situ XRD, scanning Auger electron spectroscopy and atomic force microscopy (AFM).

[1] Renner et al., Phys. Rev. B 77 (2008) 235433 [2] Borrisov et al., submitted to PCCP