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Water adsorption on vanadium oxide thin films in ambient relative humidity

Goodacre, Dana ; Blum, Monika ; Buechner, Christin ; Hoek, Harmen ; Gericke, Sabrina M. LU ; Jovic, Vedran ; Franklin, Joseph B. ; Kittiwatanakul, Salinporn ; Söhnel, Tilo and Bluhm, Hendrik , et al. (2020) In Journal of Chemical Physics 152(4).
Abstract

In this work, ambient pressure X-ray photoelectron spectroscopy (APXPS) is used to study the initial stages of water adsorption on vanadium oxide surfaces. V 2p, O 1s, C 1s, and valence band XPS spectra were collected as a function of relative humidity in a series of isotherm and isobar experiments. Experiments were carried out on two VO2 thin films on TiO2 (100) substrates, prepared with different surface cleaning procedures. Hydroxyl and molecular water surface species were identified, with up to 0.5 ML hydroxide present at the minimum relative humidity, and a consistent molecular water adsorption onset occurring around 0.01% relative humidity. The work function was found to increase with increasing relative... (More)

In this work, ambient pressure X-ray photoelectron spectroscopy (APXPS) is used to study the initial stages of water adsorption on vanadium oxide surfaces. V 2p, O 1s, C 1s, and valence band XPS spectra were collected as a function of relative humidity in a series of isotherm and isobar experiments. Experiments were carried out on two VO2 thin films on TiO2 (100) substrates, prepared with different surface cleaning procedures. Hydroxyl and molecular water surface species were identified, with up to 0.5 ML hydroxide present at the minimum relative humidity, and a consistent molecular water adsorption onset occurring around 0.01% relative humidity. The work function was found to increase with increasing relative humidity, suggesting that surface water and hydroxyl species are oriented with the hydrogen atoms directed away from the surface. Changes in the valence band were also observed as a function of relative humidity. The results were similar to those observed in APXPS experiments on other transition metal oxide surfaces, suggesting that H2O-OH and H2O-H2O surface complex formation plays an important role in the oxide wetting process and water dissociation. Compared to polycrystalline vanadium metal, these vanadium oxide films generate less hydroxide and appear to be more favorable for molecular water adsorption.

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type
Contribution to journal
publication status
published
subject
in
Journal of Chemical Physics
volume
152
issue
4
article number
044715
publisher
American Institute of Physics (AIP)
external identifiers
  • scopus:85078831362
  • pmid:32007066
ISSN
0021-9606
DOI
10.1063/1.5138959
language
English
LU publication?
yes
id
5a6cc6f6-5a6d-46c4-9872-7de7f88f7377
date added to LUP
2021-01-07 11:57:05
date last changed
2024-05-30 02:42:36
@article{5a6cc6f6-5a6d-46c4-9872-7de7f88f7377,
  abstract     = {{<p>In this work, ambient pressure X-ray photoelectron spectroscopy (APXPS) is used to study the initial stages of water adsorption on vanadium oxide surfaces. V 2p, O 1s, C 1s, and valence band XPS spectra were collected as a function of relative humidity in a series of isotherm and isobar experiments. Experiments were carried out on two VO<sub>2</sub> thin films on TiO<sub>2</sub> (100) substrates, prepared with different surface cleaning procedures. Hydroxyl and molecular water surface species were identified, with up to 0.5 ML hydroxide present at the minimum relative humidity, and a consistent molecular water adsorption onset occurring around 0.01% relative humidity. The work function was found to increase with increasing relative humidity, suggesting that surface water and hydroxyl species are oriented with the hydrogen atoms directed away from the surface. Changes in the valence band were also observed as a function of relative humidity. The results were similar to those observed in APXPS experiments on other transition metal oxide surfaces, suggesting that H<sub>2</sub>O-OH and H<sub>2</sub>O-H<sub>2</sub>O surface complex formation plays an important role in the oxide wetting process and water dissociation. Compared to polycrystalline vanadium metal, these vanadium oxide films generate less hydroxide and appear to be more favorable for molecular water adsorption.</p>}},
  author       = {{Goodacre, Dana and Blum, Monika and Buechner, Christin and Hoek, Harmen and Gericke, Sabrina M. and Jovic, Vedran and Franklin, Joseph B. and Kittiwatanakul, Salinporn and Söhnel, Tilo and Bluhm, Hendrik and Smith, Kevin E.}},
  issn         = {{0021-9606}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{American Institute of Physics (AIP)}},
  series       = {{Journal of Chemical Physics}},
  title        = {{Water adsorption on vanadium oxide thin films in ambient relative humidity}},
  url          = {{http://dx.doi.org/10.1063/1.5138959}},
  doi          = {{10.1063/1.5138959}},
  volume       = {{152}},
  year         = {{2020}},
}