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Reactive oxygen species in stoichiometric ceria: Bulk and low-index surfaces

Authors

  • Jolla Kullgren,

    1. Department of Chemistry, The Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
    2. Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany
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  • Kersti Hermansson,

    1. Department of Chemistry, The Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
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  • Peter Broqvist

    Corresponding author
    1. Department of Chemistry, The Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
    • Phone: +46-18-4713714, Fax: +46-18-513548===

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Abstract

original image

We have calculated the stabilities of some reactive oxygen species (ROS) in stoichiometric bulk ceria and at the low-index (111) and (110)-surfaces, both in vacuum and in the presence of additional O2 molecules. We find that the formation of intrinsic ROS, here oxygen superoxides (O2) and peroxides (O22–), is always endothermic at vacuum conditions and that the superoxide formation always leads to a higher formation energy than the peroxide formation. In the presence of additional O2 molecules, intrinsic peroxide formation becomes exothermic at the (110)-surface in conjunction with the formation of extrinsic superoxide ions from adsorbed O2 molecules. This coexistence of intrinsic and extrinsic ROS species is anticipated to be stable at low temperatures, and can be important for understanding the ROS chemistry for nanoceria used in low-temperature applications.

original image

Oxygen-assisted reduction of the ceria(110) surface.

(© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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