Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 59: Oxide and Insulator Interfaces II
O 59.7: Vortrag
Mittwoch, 20. März 2024, 16:30–16:45, MA 144
Selective reduction of α-Fe2O3 (0001) by hydrogen adsorption and incorporation — •Muhammad Munawar and Rossitza Pentcheva — Department of Physics, University of Duisburg Essen, Germany.
The reduction of iron oxides using hydrogen as a reducing agent may be an alternative route towards the production of green steel. In this context, we perform DFT+U calculations to explore the initial adsorption and incorporation of hydrogen in the near surface region of hematite (0001). Starting with the Fe-O3-Fe termination, which is stable in a wide range of oxygen chemical potentials, we vary the H concentration and distribution in the surface layers. The adsorption energy per H indicates that incorporation of H on the surface or in the near-surface region is favored, in contrast to incorporation in bulk hematite. H binds to an oxygen ion, while simultaneously an Fe3+ in the vicinity turns into Fe2+, leading to a pronounced distortion of the lattice. The extent of localization of the donated electron depends on the layer where H is incorporated, suggesting a varying mobility of excess electrons. We find that the bandgap decreases with increasing hydrogen concentration at the surface, whereas a semiconductor-to-half metal transition is observed when H is incorporated in deeper layers.
Funding within IMPRS SUSMET and computational time at Leibniz Rechenzentrum are acknowledged
Keywords: Hematite; surface (0001); DFT+U; Hydrogen adsorption; slab models