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  pH-dependent structure and energetics of H2O/MgO(100)

Thissen, P., Thissen, V., Wippermann, S. M., Chabal, Y. J., Grundmeier, G., & Schmidt, W. G. (2012). pH-dependent structure and energetics of H2O/MgO(100). Surface Science, 606(11-12), 902-907. doi:10.1016/j.susc.2012.01.018.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0029-77F8-3 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0029-77FA-0
Genre: Journal Article

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 Creators:
Thissen, Peter1, Author              
Thissen, Vera2, Author              
Wippermann, Stefan Martin3, Author              
Chabal, Yves J.1, Author              
Grundmeier, Guido4, Author              
Schmidt, Wolf Gero5, Author              
Affiliations:
1Department of Materials Science and Engineering, University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA, ou_persistent22              
2Lehrstuhl für Technische und Makromolekulare Chemie, Universität Paderborn, 33098 Paderborn, Germany, ou_persistent22              
3Department of Theoretical Physics, Paderborn University, 33095 Paderborn, Germany, ou_persistent22              
4University of Paderborn, Department of Technical and Macromolecular Chemistry, Warburger Str. 100, 33098 Paderborn, Germany , ou_persistent22              
5Lehrstuhl für Theoretische Physik, Universität Paderborn, 33095 Paderborn, Germany, ou_persistent22              

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Free keywords: Adsorption; Atomic force microscopy; Density functional theory; Etching; Magnesia; Magnesium; Monolayers; Monomers; pH; Quantum chemistry; Surface chemistry; Water
 Abstract: The structure and energetics of water on MgO(100) surfaces are studied by atomic force microscopy (AFM) and density-functional theory (DFT). Computationally, the adsorption of water monomers, small water clusters and water monolayers on MgO(100) surfaces is considered. The calculations predict the non-dissociative adsorption for water monomers. The potential energy surface for single monomers is characterized by very low diffusion barriers. Increasing water coverage leads to the formation of structures containing alternatively dissociated and molecularly adsorbed water molecules. The magnitude of the calculated adsorption energy per water molecule increases from 0.57 eV for the water monomer to 0.79 eV for the water monolayer. The present experimental and theoretical results show furthermore that the stability of MgO(100) surfaces in the presence of water depends on its pH value. The etching of MgO(100) surfaces in aqueous medium is studied with the AFM in situ with pH value changing from basic to acidic. While the atomically flat MgO(100) surface remains stable in basic and neutral pH ranges, it is easily etched when the pH turns below a value of 6. This agrees qualitatively with the present DFT calculations showing that square pits resulting from the etching reduce the MgO(100) surface energy in acidic environments. (C) 2012 Elsevier B.V. All rights reserved.

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Language(s): eng - English
 Dates: 2012-06
 Publication Status: Published in print
 Pages: 6
 Publishing info: -
 Table of Contents: -
 Rev. Method: -
 Degree: -

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Title: Surface Science
  Abbreviation : Surf. Sci.
Source Genre: Journal
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Publ. Info: Amsterdam : Elsevier
Pages: - Volume / Issue: 606 (11-12) Sequence Number: - Start / End Page: 902 - 907 Identifier: Other: 0039-6028
CoNE: /journals/resource/0039-6028