Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 1: Tutorial: Electro chemistry 4 condensed matter physicists

HL 1.3: Hauptvortrag

Sonntag, 15. März 2015, 17:40–18:25, H 1058

Scanning probe microscopies for electrochemical problems — •Gunther Wittstock — Carl v. Ossietzky University of Oldenburg, School of Mathematics and Science, Department of Chemistry, D-26111 Oldenburg

Electrified solid-liquid interfaces are characterized by a vertical and horizontal inhomogeneity in structure. Even well prepared single crystal electrodes show, adatoms, steps kinks and other defects. The investigation of such structures by STM has dramatically enhanced our understanding of such interfacial structures. However, the experiments were mostly performed in the absence of a Faradayic reaction (.i.e. electrolysis). With a few exceptions, electrodes are designed for controlling Faradayic reactions. High current densities are requested for efficient energy conversion devices; very low current densities are a requirement for materials that shall resist corrosion under harsh environments. Such materials (polycrystalline, multiphase or composites) show a large variation of local current densities that are neither accessible by I-V-curves nor by STM. Scanning electrochemical microscopy (SECM) provides this information. It uses the electrolysis current of a dissolved redox-active compound at a probe microelectrode to generate the signal. The electrolysis at the probe is coupled to local reaction at the sample by diffusion of reactants in the probe-sample gap. Different working modes and examples will be explained with the aim to differentiate between fundamental barriers and current instrumental limitations that might be overcome by the impact of well trained physicist.