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O: Fachverband Oberflächenphysik

O 19: Nanostructures at surfaces: Arrays

O 19.6: Vortrag

Dienstag, 24. März 2009, 11:45–12:00, SCH A215

Electrocatalysis on Nanostructured Surfaces: Electrochemical Behviour of Ir(210) — •Khaled Soliman, Felice Simeone, Ludwig Kibler, and Timo Jacob — Institut für Elektrochemie, Universität Ulm, 89069 Ulm

Recently it was found that Ir(210) transforms to a nanostructured surface morphology with three-sided nanopyramids after oxygen adsorption and annealing in ultra high vacuum (UHV) [1]. Motivated by this work we envisaged to prepare such nanofaceted surfaces outside a UHV system. We could show that faceted Ir(210) can indeed be prepared by inductive heating in presence of an inert atmosphere, which contains traces of oxygen [2]. Such surfaces are of interest for electrocatalysis. In order to characterize Ir(210) cyclic voltammetry (CV) and STM measurements were carried out. In our CV-curves of faceted Ir(210) in sulfuric acid a characteristic needle-like peak appeared, which serves as indicator for the presence and quality of the nanofacets. The STM images showed a typical structure of faceted Ir(210) surface, which could be explained by theoretical calculations employing density functional theory and thermodynamic considerations [3]. Finally, we performed first studies on the electrocatalytic behaviour of planar and nanofaceted Ir(210).

[1] I. Ermanoski, C. Kim, S. P. Kelty, T. E. Madey, Surf. Sci., 596, 89 (2005). [2] K. A. Soliman, F. C. Simeone and L. A. Kibler, Electrochem. Comm., 11, 31 (2008). [3] P. Kaghazchi, F. C. Simeone, K. A. Soliman, L. A. Kibler, T. Jacob, Faraday Discuss., 140, 69 (2008).