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Interaction of hydrogen with actinide dioxide (111) surfaces

DOI: 10.1063/1.5087577 DOI Help

Authors: James T. Pegg (University College London; Atomic Weapons Establishment (AWE) Plc) , Ashley E. Shields (Oak Ridge National Laboratory) , Mark T. Storr (Atomic Weapons Establishment (AWE) Plc) , David O. Scanlon (University College London; Diamond Light Source) , Nora H. De Leeuw (University College London; Cardiff University)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: The Journal Of Chemical Physics , VOL 150

State: Published (Approved)
Published: April 2019

Abstract: The interaction of atomic and molecular hydrogen with actinide dioxide (AnO2, An = U, Np, Pu) (111) surfaces has been investigated by DFT+U, where noncollinear 3k antiferromagnetic behaviour and spin-orbit interactions are considered. The adsorption of atomic hydrogen forms a hydroxide group, 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, shown to be due to kinetic rather than thermodynamic factors. As a barrier to the formation of a second hydroxyl group, an unusual charge distribution has been shown. This could be a limitation of a (1·1) unit cell method or an artefact of the systems. The recombination of hydrogen ions on the AnO2 (111) surfaces is favoured over hydroxide formation.

Journal Keywords: Metal oxides; Corrosion; Adsorption; Spin-orbit interactions; Chemical elements; Chemisorption; Physisorption; Chemical compounds

Subject Areas: Materials, Chemistry

Technical Areas: