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Interaction of Hydrogen with Actinide Dioxide (111) Surfaces

preprint
revised on 22.02.2019 and posted on 22.02.2019 by James Pegg, Ashley E. Shields, Mark T. Storr, David Scanlon, Nora De Leeuw
The interaction of atomic and molecular hydrogen with the actinide dioxide (AnO2, An = U, Np, Pu) (111) surfaces has been investigated by DFT+U, where noncollinear 3k antiferromagnetic (AFM) behaviour and spin-orbit interactions (SOI) are considered. The adsorption of atomic hydrogen forms a hydroxide group, and is coupled to the reduction of an actinide ion. The energy of atomic hydrogen adsorption on the UO2 (0.82 eV), NpO2 (-0.10 eV), and PuO2 (-1.25 eV) surfaces has been calculated. The dissociation of molecular hydrogen is not observed, and shown to be due to kinetic rather than thermodynamic factors. As a barrier in the formation of a second hydroxyl group, an unusual charge distribution has been shown. This is possibly a limitation of a (1·1) unit cell method. The recombination of hydrogen ions on the AnO2 (111) surfaces is favoured over hydroxide formation.

Funding

EP/G036675

EP/K016288

History

Email Address of Submitting Author

pegg.james.t@gmail.com

Institution

University College London

Country

United Kingdom

ORCID For Submitting Author

0000-0002-6743-8651

Declaration of Conflict of Interest

None

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in The Journal of Chemical Physics

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