First-principles study of O2 adsorption on the α-U(001) surface

• Systematic study on the adsorption of O2 on α-U(001) surface.
• Detailed investigation of the molecular and atomic adsorption structure of O2 on α-U(001) surface.
• Deep insight into the binding nature of U–O through the electronic properties analysis.

First-principles calculations based on density functional theory (DFT) have been performed to investigate the adsorption structures and electronic properties for O2 on the α-U(001) surface. It was found that O2 tends to dissociate with significant energetic preference compared to molecular adsorption. When approaching the surface perpendicularly along top site, the O2 adsorbates were found to remain as molecule on the surface. The density of states of the system showed strong hybridization features for O2p, U6d and U5f states in the case of dissociative adsorption which is weaker for molecular adsorption. Further electronic properties analysis demonstrated that the bonding character of U–O bond is related to the symmetry of the adsorption site. Top site configuration showed stronger covalent component for the U–O bond, while the ionic character was found to be more obvious for hollow site adsorption.