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Issue 14, 2011
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Structure of clean and hydrated α-Al2O3 (1[1 with combining macron]02) surfaces: implication on surface charge

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Abstract

Periodic DFT calculations coupled to a first-principle thermodynamic approach have allowed us to establish a surface phase diagram for the different terminations of the α-Al2O3 (1[1 with combining macron]02) surface in various temperature and water pressure conditions. Theoretical results are compared with previous experimental data from the literature. Under a wide range of temperature and water pressure (including ambient conditions) the most stable surface (denoted C2_1H2O in this work) is terminated with singly coordinated hydroxyls on four-fold coordinated aluminium (Al4C1-OH) while most existing surface models are only considering six-fold coordinated surface Al atoms as in the bulk structure of alumina. The presence of more acidic Al4C1-OH sites helps explain the low Point of Zero Charge (PZC) (between 5 and 6) determined from the onset of Mo oxoanions adsorption on (1[1 with combining macron]02) single crystal wafers. It is also postulated that another termination (corresponding to the hydration of the non-polar, stoichiometric surface, stable in dehydrated conditions) may be observed in aqueous solution depending on the surface preparation conditions.

Graphical abstract: Structure of clean and hydrated α-Al2O3 (1 [[1 with combining macron]] 02) surfaces: implication on surface charge

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Publication details

The article was received on 23 Jul 2010, accepted on 02 Feb 2011 and first published on 07 Mar 2011


Article type: Paper
DOI: 10.1039/C0CP01295E
Citation: Phys. Chem. Chem. Phys., 2011,13, 6531-6543
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    Structure of clean and hydrated α-Al2O3 (1[1 with combining macron]02) surfaces: implication on surface charge

    A. Tougerti, C. Méthivier, S. Cristol, F. Tielens, M. Che and X. Carrier, Phys. Chem. Chem. Phys., 2011, 13, 6531
    DOI: 10.1039/C0CP01295E

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