Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 12: Oxides and insulators: Adsorption
O 12.2: Vortrag
Montag, 22. März 2010, 15:15–15:30, H33
H and H2O adsorption on Fe3O4(001): Adsorbate induced charge and orbital order — •Narasimham Mulakaluri1,2, Rossitza Pentcheva1, Wolfgang Moritz1, and Matthias Scheffler2 — 1Section Crystallography, Dept. for Earth and Environmental Sciences, University of Munich — 2Fritz-Haber-Institut der MPG, Berlin
Besides potential applications in spintronics, magnetite plays an important role in many environmental redox reactions. Using density functional theory together with an on-site Coulomb repulsion term (GGA+U), we investigate the adsorption of H2O and H on Fe3O4(001) surface and its influence on the electronic structure. The surface phase diagram, compiled within the framework of ab initio atomistic thermodynamics reveals dissociative adsorption of water especially at surface defect sites. At higher water vapour pressures a partial dissociation sets in, where a chain of hydrogen bonded H2O and OH groups forms[1]. The adsorbates (H2O, OH, H) are found to induce a unique charge and orbital ordering in the surface and sub-surface layers. This feature can be used to tailor the catalytic properties as well as half-metallicity of the material.
[1] N. Mulakaluri et.al, Phys. Rev. Lett 103, 176102 (2009).