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 O-2 and H2O molecules to alpha-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 alpha-uranium bulk well. Of all 7 low index surfaces of alpha-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 O-2 and H2O molecules are investigated separated. The O-2 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 O-2 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.