Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.68: Poster

Wednesday, March 28, 2007, 17:00–19:30, Poster C

Corrosion Inhibition by Diphenylviologen on Cu(100) — •Knud Gentz, Peter Broekmann, Simone Koßmann, Barbara Kirchner, and Klaus Wandelt — Institut für Physikalische und Theoretische Chemie, Universität Bonn

The effect of preadsorbed Diphenylviologen (DPV) on the corrosion of a bromide-modified Cu(100) surface in 5mM sulfuric acid has been studied by cyclic voltammetry (CV) and in-situ STM measurements, conducted with a home-built electrochemical STM [3]. In the anodic sweep, the oxidative dissolution of Cu(100) under the given conditions is shifted about 100 mV to more positive potentials with respect to the same surface in the absence of the viologen. Certain structural elements of DPV on the surface lead to the proposal of a tentative model of the mechanism of the corrosion inhibition, that has been developed on basis of DFT calculations of the structure of the viologen. The halide-modification generates a high surface mobility of the copper, leading to ordered step-edges aligned with the <010> directions of the halide lattice. These ordered step-edges induce a structure of the viologen near the edge, which is different from the structures on the terrasses. The compact arrangement of this structure effectively blocks the step-edges as reactive sites for the copper corrosion.

[1] Wilms et al., Rev. Sci. Instr., 70 7 (1999) 473