Competing defect mechanisms and hydrogen adsorption on Li-doped MgO low index surfaces: A DFT+U study?

David O. Scanlon, Aron Walsh, Benjamin J. Morgan, Graeme W. Watson

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Three competing defect configurations of Li-doping of MgO on the (100), (110) and (111) low index surfaces have been investigated using GGA + U. The three configurations investigated on each of the surfaces were: substitution of Li for Mg with the formation of a compensating oxygen hole state ([Li' Mg - O•o]), substitution of Li for Mg with the addition of a Li surface interstitial ([Li'MgLi•i]) and the clustering of two Li ions with the formation of a neutral [Li' MgVo ••Li'Mg] oxygen vacancy. The electronic structure, geometry and energetics of these defects are examined, and the effect on catalytic activity is discussed. Hydrogen abstraction from methane on the three surfaces is also investigated. Our results demonstrate that the energetics associated with hydrogen adsorption are strongly surface dependent, with the (111) oxygen terminated surface indicated as being the most promising catalytically.

Original languageEnglish
Pages (from-to)395-404
Number of pages10
Journale-Journal of Surface Science and Nanotechnology
Volume7
DOIs
StatePublished - 4 Apr 2009

Keywords

  • Catalysis
  • Density functional calculations
  • Magnesium oxides
  • Surface defects
  • Surface electronic phenomena

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