Divendres 3 d'abril a l'EPSC — Seminari sobre In-situ X-Ray diffraction of electrochemical corrosion

Divendres 3 d'abril, de 12:30 a 14:00

Títol: In situ X-Ray diffraction of electrochemical corrosion

Ponent: Prof. Frank Renner, Max-Planck-Institut für Eisenforschung, Düsseldorf

LLoc: Aula 021B EPSC-C4

Abstract: The widespread emergence of synchrotron light sources in recent years enabled in-situ surface X-ray diffraction to become one of the most productive methods next to scanning probe techniques to access structural parameters of (buried) interfaces at the atomic and nanometer scale.Dealloying is a well-known process occurring at alloy surfaces, which are composed of elements with widely different Nernst potentials. Dealloying of noble metal alloys as a model process was studied since the early days of corrosion science and is still under debate, mainly because in-situ atomic-scale information became available only in the last two decades. Dealloying of Cu3Au(111) in 0.1 M H2SO4 has been investigated by in-situ X-ray diffraction. We studied systematically the selective dissolution of Cu as a function of potential and could follow the initial growth of an ultra-thin epitaxial Au-rich layer on Cu3Au(111) and its evolution to pure Au islands at more elevated potentials. Both succeeding surface structures exhibited entirely a reversed atomic layer stacking sequence with respect to the substrate. Close to the critical potential the reversed Au layer vanishes and substrate-oriented Au ligaments occur. A short overview of our development of a UHV-compatible electrochemical in-situ cell in line with recent activities using ionic liquids as electrolyte will be given.