Water Adsorption on AnO2 {111}, {110} and {100} Surfaces (An = U, Pu); A DFT+U Study

Bengt Tegner, Marco Molinari, Andrew Kerridge, Stephen C Parker, Nikolas Kaltsoyannis

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    Abstract

    The interactions between water and the actinide oxides UO2 and PuO2 are important both fundamentally, and when considering the long-term storage of spent nuclear fuel. However, experimental studies in this area are severely limited by plutonium’s intense radioactivity, and hence we have recently begun to investigate these interactions computationally. In this article we report the results of plane-wave density functional theory calculations of the interaction of water with the {111}, {110} and {100} surfaces of UO2 and PuO2, using a Hubbard-corrected potential (PBE+U) approach to account for the strongly-correlated 5f electrons. We find a mix of molecular and dissociative water adsorption to be most stable on the {111} surface, whereas the fully dissociative water adsorption is most stable on the {110} and {100} surfaces, leading to a fully hydroxylated monolayer. From these results we derive water desorption temperatures at various pressures for the different surfaces. These increase in the order {111}<{110}<{100}, and these data are used to propose an alternative interpretation for the two experimentally determined temperature ranges for water desorption from PuO2.
    Original languageEnglish
    Pages (from-to)1675–1682
    JournalJournal of Physical Chemistry C
    Volume121
    Early online date22 Dec 2016
    DOIs
    Publication statusPublished - 26 Jan 2017

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