Water adsorption on vanadium oxide thin films in ambient relative humidity
- Univ. of Auckland, Auckland (New Zealand); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); MacDiarmid Inst. for Advanced Materials and Nanotechnology, Wellington (New Zealand)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of Twente, Enschede (The Netherlands)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lund Univ., Lund (Sweden)
- MacDiarmid Inst. for Advanced Materials and Nanotechnology, Wellington (New Zealand); National Isotope Center, GNS Science, Lower Hutt (New Zealand)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. College London, London (United Kingdom)
- Univ. of Virginia, Charlottesville, VA (United States); Chulalongkorn Univ., Bangkok (Thailand)
- Univ. of Auckland, Auckland (New Zealand); MacDiarmid Inst. for Advanced Materials and Nanotechnology, Wellington (New Zealand)
- Fritz Haber Inst. of the Max Planck Society, Berlin (Germany)
- Boston Univ., MA (United States)
Here 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.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); European Union (EU)
- Grant/Contract Number:
- AC02-05CH11231; 705339; FG02-98ER45680
- OSTI ID:
- 1605264
- Journal Information:
- Journal of Chemical Physics, Vol. 152, Issue 4; ISSN 0021-9606
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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