Coverage-dependent oxidation and reduction of vanadium supported on anatase TiO2(1 0 1)

Research output: Contribution to journalArticle

Abstract

© 2018 Elsevier Inc. Using a multi-technical approach, we studied the oxidation of anatase TiO 2 (1 0 1)-supported vanadium (V) clusters at room temperature. We found by ex situ XPS that the highest oxidation state is +4 at sub-monolayer coverage regardless of the O 2 pressure, and STM studies revealed that the initial oxidation proceeds through oxygen-induced disintegration of V clusters into monomeric VO 2 species. By contrast, for ∼2 monolayer V coverage, a partial oxidation to V 5+ is achieved. By in situ APXPS measurements, we found that V can be maintained in the V 5+ oxidation state irrespective of the coverage; however, in the sub-monolayer range, an O 2 pressure of at least ∼1 × 10 −5 mbar is needed. Our results suggest an enhanced reducibility of V in direct contact with the TiO 2 support compared to V in the 2nd layer, which is in line with the observed optimum V 2 O 5 loading in catalytic applications just slightly below a full monolayer.

Details

Authors
  • Stig Koust
  • Benjamin N. Reinecke
  • Kræn C. Adamsen
  • Igor Beinik
  • Karsten Handrup
  • Zheshen Li
  • Poul G. Moses
  • Joachim Schnadt
  • Jeppe V. Lauritsen
  • Stefan Wendt
Organisations
External organisations
  • Aarhus University
  • Lund University
  • Haldor Topsøe A/S
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Other Chemical Engineering

Keywords

  • Ambient pressure X-ray photoelectron spectroscopy (APXPS), Anatase TiO (1 0 1) 2, Oxidation, Scanning tunneling microscopy (STM), SCR catalysis, Vanadium, X-ray photoelectron spectroscopy (XPS)
Original languageEnglish
Pages (from-to)118-126
Number of pages9
JournalJournal of Catalysis
Volume360
StatePublished - 2018 Apr 1
Peer-reviewedYes