Manuscript: Interaction of Hydrogen with Actinide Dioxide (011) Surfaces J ! "egg et al Interaction of Hydrogen with Actinide Dioxide (011) Surfaces James T. Pegg,1,2* Ashley E. Shields,3 Mark T. Storr,2 David O. Scanlon,1,4 and Nora H. de Leeuw.1,5* 1 Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom. 2 Atomic Weapons Establishment (AWE) Plc, Aldermaston, Reading, RG7 4PR, UK. 3 Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA 4 Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom. 5 School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom;
[email protected] Keywords: Nuclear Fuel, Actinide Dioxide, Noncollinear Magnetism, DFT, Hydrogen Interaction. Abstract: The corrosion and oxidation of actinide metals, leading to the formation of metal- oxide surface layers with the catalytic evolution of hydrogen, impacts the management of nuclear materials. Here, the interaction of hydrogen with actinide dioxide (AnO2, An = U, Np, Pu) (011) surfaces by Hubbard corrected Density Functional Theory (PBEsol+U) has been studied, including spin-orbit interactions and non-collinear 3k anti-ferromagnetic behaviour. The actinide dioxides crystalize in the fluorite-type structure, and although the (111) surface dominates the crystal morphology, the (011) surface energetics may lead to more significant interaction with hydrogen. The energies of atomic hydrogen adsorption onto UO2 (0.44 eV), NpO2 (-0.47 eV), and PuO2 (-1.71 eV) have been calculated. Hydrogen dissociates on the "uO% (011) surface; however, UO2 (011) and NpO2 (011) surfaces are relatively inert.