Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Focus Session: Structure and Chemistry of Metal-Oxide Surfaces II

O 55.7: Vortrag

Mittwoch, 14. März 2018, 12:00–12:15, MA 005

Structural changes in Fe₃O₄ surfaces upon adsorption of organic acids - a DFT study — •Kai Sellschopp¹, Björn Arndt^2,3, Marcus Creutzburg^2,3, Heshmat Noei², Andreas Stierle^2,3, Stefan Müller¹, and Gregor Feldbauer¹ — ¹Institute of Advanced Ceramics, Hamburg University of Technology — ²DESY NanoLab, Deutsches Elektronensynchrotron, Hamburg — ³Physics Department, Hamburg University

The structure of the major surfaces of magnetite, namely the (001) and (111) surfaces, has been a matter of debate for a long time. For the clean (001) surface the debate seems to be settled since the subsurface cation vacancy (SCV) reconstruction was found [1]. The associated √2×√2 diffraction pattern changes, however, to a 1× 1 pattern upon adsorption of carboxylic acids [2]. In oder to understand this structural change, we investigated the energetics of adsorption for this system and the implications for surface stability using density functional theory (DFT) calculations. Furthermore, the analysis of different adsorption sites and the electronic structure gives insight into the mechanisms of this structural change. Finally, DFT results are compared to surface X-ray diffraction (SXRD) measurements. According to our findings, adsorption of carboxylic acids may also affect the termination of the magnetite (111) surface.
[1] R. Bliem et al., Science 346 (6214), 1215-1218, 2014
[2] O. Gamba et al., J. Phys. Chem. C 119 (35), 20459-20465, 2015