Density functional study of H2O molecule adsorption on α-U(001) surface

Abstract

Periodic density functional theory (DFT) calculations were performed to investigate the adsorption of H2O on U(001) surface. The metallic nature of uranium atom and different adsorption sites of U(001) surface play key roles in the H2O molecular dissociate reaction. The long-bridge site is the most favorable site of H2O-U(001) adsorption configuration. The triangle-center site of the H atom is the most favorable site of HOH-U(001) adsorption configuration. The interaction between H2O and U surface is more evident on the first layer than that on any other two sub-layers. The dissociation energy of one hydrogen atom from H2O is -1.994 to -2.215 eV on U(001) surface, while the dissociating energy decreases to -3.351 to -3.394 eV with two hydrogen atoms dissociating from H2O. These phenomena also indicate that the Oads can promote the dehydrogenation of H2O. A significant charge transfer from the first layer of the uranium surface to the H and O atoms is also found to occur, making the bonding partly ionic.

Co-adsorption of O2and H2O onα-uranium (110) surface: A density functional theory study

“…To the best of our knowledge, the (001) surface of α-uranium has been investigated extensively. [39,[46][47][48] However, there are no systematical investigations on all seven low index surfaces, we perform calculations on the surface energies of the seven low index surfaces to obtain comprehensive knowledge about the surface energy of α-uranium low index surface. The atoms in crystal surface are located in a non-equilibrium force field, and they are different from the atoms in bulk which are located in an equilibrium or a metaequilibrium crystal field, and the surface atoms will relax to equilibrium positions in the direction toward the minimum energy.…”