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Adsorption of CO on the Fe3O4(001) Surface

Hulva, Jan; Jakub, Zdeněk; Novotny, Zbynek; Johansson, Niclas LU ; Knudsen, Jan LU ; Schnadt, Joachim LU ; Schmid, Michael; Diebold, Ulrike and Parkinson, Gareth S. (2018) In Journal of Physical Chemistry B 122(2). p.721-729
Abstract

The interaction of CO with the Fe3O4(001)-(√2 × √2)R45° surface was studied using temperature-programmed desorption (TPD), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS), the latter both under ultrahigh vacuum (UHV) conditions and in CO pressures up to 1 mbar. In general, the CO-Fe3O4 interaction is found to be weak. The strongest adsorption occurs at surface defects, leading to small TPD peaks at 115, 130, and 190 K. Desorption from the regular surface occurs in two distinct regimes. For coverages up to two CO molecules per (√2 × √2)R45° unit cell, the desorption maximum shows a large shift with increasing coverage, from initially 105 to 70 K. For coverages... (More)

The interaction of CO with the Fe3O4(001)-(√2 × √2)R45° surface was studied using temperature-programmed desorption (TPD), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS), the latter both under ultrahigh vacuum (UHV) conditions and in CO pressures up to 1 mbar. In general, the CO-Fe3O4 interaction is found to be weak. The strongest adsorption occurs at surface defects, leading to small TPD peaks at 115, 130, and 190 K. Desorption from the regular surface occurs in two distinct regimes. For coverages up to two CO molecules per (√2 × √2)R45° unit cell, the desorption maximum shows a large shift with increasing coverage, from initially 105 to 70 K. For coverages between 2 and 4 molecules per (√2 × √2)R45° unit cell, a much sharper desorption feature emerges at ∼65 K. Thermodynamic analysis of the TPD data suggests a phase transition from a dilute 2D gas into an ordered overlayer with CO molecules bound to surface Fe3+ sites. XPS data acquired at 45 K in UHV are consistent with physisorption. Some carbon-containing species are observed in the near-ambient-pressure XPS experiments at room temperature but are attributed to contamination and/or reaction with CO with water from the residual gas. No evidence was found for surface reduction or carburization by CO molecules.

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organization
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Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry B
volume
122
issue
2
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85040781867
ISSN
1520-6106
DOI
language
English
LU publication?
yes
id
d84cc588-0241-48f5-ad16-dd15579ae3df
date added to LUP
2018-01-30 10:39:14
date last changed
2018-05-29 10:55:28
@article{d84cc588-0241-48f5-ad16-dd15579ae3df,
  abstract     = {<p>The interaction of CO with the Fe<sub>3</sub>O<sub>4</sub>(001)-(√2 × √2)R45° surface was studied using temperature-programmed desorption (TPD), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS), the latter both under ultrahigh vacuum (UHV) conditions and in CO pressures up to 1 mbar. In general, the CO-Fe<sub>3</sub>O<sub>4</sub> interaction is found to be weak. The strongest adsorption occurs at surface defects, leading to small TPD peaks at 115, 130, and 190 K. Desorption from the regular surface occurs in two distinct regimes. For coverages up to two CO molecules per (√2 × √2)R45° unit cell, the desorption maximum shows a large shift with increasing coverage, from initially 105 to 70 K. For coverages between 2 and 4 molecules per (√2 × √2)R45° unit cell, a much sharper desorption feature emerges at ∼65 K. Thermodynamic analysis of the TPD data suggests a phase transition from a dilute 2D gas into an ordered overlayer with CO molecules bound to surface Fe<sup>3+</sup> sites. XPS data acquired at 45 K in UHV are consistent with physisorption. Some carbon-containing species are observed in the near-ambient-pressure XPS experiments at room temperature but are attributed to contamination and/or reaction with CO with water from the residual gas. No evidence was found for surface reduction or carburization by CO molecules.</p>},
  author       = {Hulva, Jan and Jakub, Zdeněk and Novotny, Zbynek and Johansson, Niclas and Knudsen, Jan and Schnadt, Joachim and Schmid, Michael and Diebold, Ulrike and Parkinson, Gareth S.},
  issn         = {1520-6106},
  language     = {eng},
  month        = {01},
  number       = {2},
  pages        = {721--729},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry B},
  title        = {Adsorption of CO on the Fe<sub>3</sub>O<sub>4</sub>(001) Surface},
  url          = {http://dx.doi.org/},
  volume       = {122},
  year         = {2018},
}