Spectroscopic investigation of vanadium speciation in vanadium-doped nanocrystalline anatase

V Luca, S Thomson, Russell Francis Howe

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Abstract

The speciation of vanadium doped into anatase particles of 50-90 Angstrom diameter has been studied by a variety of techniques including solid state V-51 NMR, EPR, XPS and Raman spectroscopy. EPR spectra of V-doped anatase are extremely complex showing up to five different V4+ centres (species A-E). Partial spin Hamiltonian parameters for these species have been determined and ascribed to interstitial (species A) and substitutional V4+ (species B-D), as well as surface V4+-rich clusters (species E). Solid state V-51 NMR also shows the presence of several V5+ species that exhibit both tetrahedral and octahedral coordination and which are attributed to structural and residual surface V5+. It is shown by NMR, Raman spectroscopy and XPS that the dissolution of this residual surface vanadium component into the anatase structure becomes increasingly difficult as the vanadium concentration increases.

Original languageEnglish
Pages (from-to)2195-2202
Number of pages8
JournalJournal of the Chemical Society, Faraday Transactions
Volume93
Issue number12
Publication statusPublished - 21 Jun 1997

Keywords

  • solid-state NMR
  • oxide catalysts
  • TIO2 particles
  • colloids
  • rutile
  • water

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