Structure of clean and hydrated α-Al2O3 (102) surfaces: implication on surface charge

Asma Tougerti; Christophe Méthivier; Sylvain Cristol; Frederik Tielens; Michel Che; Xavier Carrier

doi:10.1039/C0CP01295E

Structure of clean and hydrated α-Al₂O₃ (102) surfaces: implication on surface charge†

Asma Tougerti,^ab Christophe Méthivier,^ab Sylvain Cristol,^c Frederik Tielens,^ab Michel Che^ab and Xavier Carrier*^ab

* Corresponding authors

^a UPMC—Université Pierre et Marie Curie (Paris 06), UMR 7197, Laboratoire de Réactivité de Surface, F-75005 Paris, France
E-mail: xavier.carrier@upmc.fr
Fax: +33 1 44 27 60 33
Tel: +33 1 44 27 60 05

^b CNRS, UMR 7197, Laboratoire de Réactivité de Surface, F-75005 Paris, France

^c Unité de Catalyse et de Chimie du Solide, UMR CNRS 8181, Université Lille 1, F-59650 Villeneuve d'Ascq, France

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 (Al_4C-μ₁-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 Al_4C-μ₁-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.

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Article information

DOI: https://doi.org/10.1039/C0CP01295E
Article type: Paper
Submitted: 23 Jul 2010
Accepted: 02 Feb 2011
First published: 07 Mar 2011

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Phys. Chem. Chem. Phys., 2011,13, 6531-6543

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Structure of clean and hydrated α-Al₂O₃ (102) 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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