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Dissociation of water on oxygen-covered Rh{111}

Shavorskiy, A., Eralp, T., Ataman, E., Isvoranu, C., Schnadt, J., Andersen, J. N. and Held, G. (2009) Dissociation of water on oxygen-covered Rh{111}. Journal of Chemical Physics, 131 (21). 214707. ISSN 0021-9606

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To link to this article DOI: 10.1063/1.3266941

Abstract/Summary

The adsorption of water and coadsorption with oxygen on Rh{111} under ultrahigh vacuum conditions was studied using synchrotron-based photoemission and photoabsorption spectroscopy. Water adsorbs intact on the clean surface at temperatures below 154 K. Irradiation with x-rays, however, induces fast dissociation and the formation of a mixed OH+H(2)O layer indicating that the partially dissociated layer is thermodynamically more stable. Coadsorption of water and oxygen at a coverage below 0.3 monolayers has a similar effect, leading to the formation of a hydrogen-bonded network of water and hydroxyl molecules at a ratio of 3:2. The partially dissociated layers are more stable than chemisorbed intact water with the maximum desorption temperatures up to 30 K higher. For higher oxygen coverage, up to 0.5 monolayers, water does not dissociate and an intact water species is observed above 160 K, which is characterized by an O 1s binding energy 0.6 eV higher than that of chemisorbed water and a high desorption temperature similar to the partially dissociated layer. The extra stabilization is most likely due to hydrogen bonds with atomic oxygen.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:11613
Uncontrolled Keywords:CHEMICAL-COMPOSITION, METAL-SURFACES, ADSORPTION, PT(111), PD(111), HYDROXYL, RU(0001), COADSORPTION, REACTIVITY, MECHANISM

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