Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 39: Oxide and Insulator Surfaces: Structure, Epitaxy and Growth II
O 39.5: Vortrag
Dienstag, 21. März 2017, 15:00–15:15, WIL C107
The (O12) surfaces of hematite and their interactions with water - a DFT study — •Magdalena Bichler1, Florian Kraushofer2, Zdenek Jakub2, Gareth Parkinson2, and Peter Blaha1 — 1Institute of Materials Chemistry, TU Wien — 2Institute of Applied Physics, TU Wien
Hematite (α-Fe2O3) is a promising material for electrochemical water splitting with a suitable bandgap (2.2 eV) and valence band edge position. Moreover, the material is cheap, stable in water and harmless in terms of ecology. Nevertheless, it shows poor electrochemical performance, which might be improved by morphology and surface modifications.
We focus on the (012) surface of hematite (R-cut). Two different types are known. On the one hand, the (1x1) bulk terminated, stoichiometric surface exists, but at low O2 pressure, a (2x1) reconstruction with missing oxygen atoms is formed. [1]
We carried out ab initio calculations by using the WIEN2k code. [2] In addition, STM, AFM and LEED experiments were done. Based on our DFT calculations, we present a new model of the (2x1) reconstruction, which is energetically more stable than the one that has been proposed so far [3] and agrees with experiment. Furthermore, the surfaces’ interactions with water were investigated in both experiment and theory.
[1] M. A. Henderson et al., Surf. Sci. 1998, 417, 66-81
[2] http://www.wien2k.at
[3] M. A. Henderson, Surf. Sci. 2010, 604, 1197-1201