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

Koust, Stig; Reinecke, Benjamin N.; Adamsen, Kræn C.; Beinik, Igor; Handrup, Karsten LU ; Li, Zheshen; Moses, Poul G.; Schnadt, Joachim LU ; Lauritsen, Jeppe V. and Wendt, Stefan (2018) In Journal of Catalysis 360. p.118-126
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... (More)
© 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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
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)
in
Journal of Catalysis
volume
360
pages
9 pages
publisher
Elsevier
external identifiers
  • scopus:85042112637
ISSN
0021-9517
DOI
10.1016/j.jcat.2018.01.016
language
English
LU publication?
yes
id
41638f0f-52cf-4c9f-ae66-9c471e57d76b
date added to LUP
2018-03-05 12:42:51
date last changed
2018-06-10 05:27:18
@article{41638f0f-52cf-4c9f-ae66-9c471e57d76b,
  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.},
  author       = {Koust, Stig and Reinecke, Benjamin N. and Adamsen, Kræn C. and Beinik, Igor and Handrup, Karsten and Li, Zheshen and Moses, Poul G. and Schnadt, Joachim and Lauritsen, Jeppe V. and Wendt, Stefan},
  issn         = {0021-9517},
  keyword      = {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)},
  language     = {eng},
  month        = {04},
  pages        = {118--126},
  publisher    = {Elsevier},
  series       = {Journal of Catalysis},
  title        = {Coverage-dependent oxidation and reduction of vanadium supported on anatase TiO2(1 0 1)},
  url          = {http://dx.doi.org/10.1016/j.jcat.2018.01.016},
  volume       = {360},
  year         = {2018},
}