Surface sensitivity in lithium-doping of MgO: A density functional theory study with correction for on-site coulomb interactions

David O. Scanion, Aron Welsh, Benjamin J. Morgan, Michael Nolan, Joanne Fearon, Graeme W. Watson

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88 Citations (Scopus)

Abstract

Catalytic conversion of methane to higher hydrocarbons takes place on lithium-doped MgO. To date, investigations of the Li-doping process have been confined to the bulk and the (100) surface. In this paper, we describe an investigation of the surface dependence of Li-doping of MgO through an in-depth study of the (100), (110), and (111) low index surfaces using density functional theory with correction for on-site Coulomb interactions (DFT+U). Three competing defect configurations were investigated on each of the surfaces; substitution of Li for Mg with the formation of a compensating oxygen hole state, substitution of Li for Mg with the addition of a Li surface interstitial and the clustering of two Li ions with the formation of a neutral [Li′Mg V**OLi′Mg] oxygen vacancy. Our results demonstrate that the energetics associated with the Li-doping of MgO are strongly surface dependent. On the (100) surface, there is an energy cost associated with Li-doping, whereas on the (110) and (111) surfaces Li-doping is energetically favored. The implications of the results for the catalytic activity of the different surface terminations of MgO are discussed.

Original languageEnglish
Pages (from-to)7971-7979
Number of pages9
JournalJournal of Physical Chemistry C
Volume111
Issue number22
DOIs
Publication statusPublished - 2007 Jun 7

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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