Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 81: Oxide and Insulator Surfaces: Adsorption II
O 81.3: Vortrag
Mittwoch, 22. März 2017, 16:30–16:45, WIL C107
DFT Study of Water Adsorption on Cation Doped (001)-MgO Surfaces — •Thomas Ruh1, Christian Knoll2, Danny Müller2, Peter Weinberger2, and Peter Blaha1 — 1Institute of Materials Chemistry, TU Wien — 2Institute of Applied Synthetic Chemistry, TU Wien
Combined hydration/dehydration processes of oxide/hydroxide systems can be used for storage of industrial excess heat. An example is the system CaO/Ca(OH)2 [1]. The exothermal reaction of CaO and water (to release stored energy) is fast and complete at ambient temperature; however, the reverse reaction to recover CaO requires high temperatures. For several applications a system operable at lower temperatures would be desirable.
A potential candidate is the system MgO/Mg(OH)2. However, the reaction of the oxide with water is slow and incomplete at room temperature. Many studies of the adsorption behaviour of water on MgO surfaces suggest that the reaction is kinetically hindered. Hu et al [2], for instance, found in a DFT study, that adsorbed water does not dissociate on MgO surfaces, whereas on CaO surfaces hydroxyls are formed.
In the present work we investigate the effects of cation doping of the (001)-surface of MgO with different cations on the formation and subsequent stability of hydroxyls.
[1] S. Jujimoto et al., Energ. Convers. Manage., 2002, 43, 947-960 [2] X.L. Hu et al., Phys. Chem. Chem. Phys., 2011, 13, 12447-12453 [3] http://www.wien2k.at