Examination of oxygen vacancy formation in Mn-Doped CeO2 (111) using DFT+U and the hybrid functional HSE06

Matthew D. Krcha, Michael J. Janik

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38 Scopus citations

Abstract

MnOx-CeOx mixed oxide systems exhibit interesting sulfur adsorption capacities and catalytic activity. We examined the electronic structure of Mn-doped fluorite CeO2 bulk solid and surface using density functional theory (DFT) with the Hubbard U term or the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional. We specifically evaluate the reducibility and formation energies of Mn-doped CeO2 surfaces. The use of a U value on the d-states of Mn is examined, and a value of 4 eV is chosen based upon results from DFT+U calculations on bulk MnOx,1 XANES characterization of oxidation states in calcined and reduced Mn-doped CeO2, and comparison with HSE06 hybrid functional results. Electronic structure impacts of the U inclusion are discussed. The concentration and orientation of Mn atoms doped into the surface of CeO2 have a great influence on the reducibility of the surface. Based upon formation energies, Mn will not favor doping into the surface of CeO2 in a fully oxidized system (Mn4+). Under reducing environments, Mn will dope into the surface with oxygen vacancies present (Mn3+ and Mn2+). The first oxygen vacancy is not likely catalytically important in fluorite MnO x-CeOx systems as formation of the fully oxidized surface is not stable. A greater degree of reduction would occur during a catalyzed redox reaction.

Original languageEnglish (US)
Pages (from-to)10120-10131
Number of pages12
JournalLangmuir
Volume29
Issue number32
DOIs
StatePublished - Aug 13 2013

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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