Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 76: Focussed Session: Solid-liquid Interfaces II

O 76.7: Vortrag

Donnerstag, 14. März 2013, 18:15–18:30, H31

Aligning electronic energy levels in electrochemical systems — •Mira Todorova and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf

The relative position of a solid's band structure or an ion transition level with respect to the water energy levels is crucial for the understanding and quantification of electrochemical reactions at solid/liquid interfaces. In terms of electronic structure water has been shown to exhibit features similar to an amorphous semiconductor [1]. As such, it does not have well defined band edges, which makes the technique of aligning defect levels with respect to the band-edges, commonly used in semiconductor physics, not very practicable. Other alignment possibilities, which exploit the reduced sensitivity of an electrostatic potential or some deep level within the band-gap of a material with respect to the band-edge positions and their possible shift, upon changing the used exchange-correlations functional, have been discussed in the semiconductor literature. We explore the applicability of such techniques to electrochemical problems, by discussing the alignment of the electronic levels of ions in water. Utilising our findings and our recently developed method to identify the electrode potential and pH-value within an electrochemical system we explore the stability of ZnO surfaces as a function of environmental conditions.

[1] F. Williams, S.P. Varma, and S. Hillenius, J. Chem. Phys. 64, 1549 (1976).