Co-adsorption of O₂ and H₂O on α-uranium (110) surface: A density functional theory study

First-principles calculations based on density functional theory corrected by Hubbard parameter U (DFT+U) are applied to the study on the co-adsorption of O₂ and H₂O molecules to α-U(110) surface. The calculation results show that DFT+U method with U_eff=1.5 eV can yield the experimental results of lattice constant and elastic modulus of α-uranium bulk well. Of all 7 low index surfaces of α-uranium, the (001) surface is the most stable with lowest surface energy while the (110) surface possesses the strongest activity with the highest surface energy. The adsorptions of O₂ and H₂O molecules are investigated separated. The O₂ dissociates spontaneously in all initial configurations. For the adsorption of H₂O molecule, both molecular and dissociative adsorptionsoccur. Through calculations of co-adsorption, it can be confirmed that the inhibition effect of O₂ on the corrosion of uranium by water vapor originates from the preferential adsorption mechanism, while the consumption of H atoms by O atoms exerted little influence on the corrosion of uranium.