The Interaction of Hydrogen with Actinide Dioxide (111) Surfaces

02 January 2019, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

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.

Keywords

DFT+U
Actinide Dioxides
Surfaces

Supplementary materials

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The Interaction of Hydrogen with Actinide Dioxide (111) Surfaces(ESI)
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The Interaction of Hydrogen with Actinide Dioxide (111) Surfaces(Main)
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