Adsorption and dissociation behavior of H2O on PuH2 (1 1 0) surface: A density functional theory study

Abstract The reaction between water and plutonium hydride plays a significant role in the oxidation and corrosion rate of plutonium materials. The adsorption and dissociation of water molecule on PuH2 (1 1 0) surface have been studied by first-principles GGA + U method. To search the more favorable adsorption sites and adsorption types of H2O in terms of energy, the adsorption energies of H2O on different active sites were compared. The results reveal that the adsorption of H2O molecule on the surface of PuH2 (1 1 0) basically presents chemical adsorption, while the adsorption direction of H2O molecule parallel to the PuH2 (1 1 0) surface appears to be preferentially adsorbed on the top of Pu atom. We analyze the vibrational frequencies of H2O molecule adsorbed on the surface. It is found that there is a red shift phenomenon under the action of surface atoms. Two possible dissociation pathways of H2O molecule on PuH2 (1 1 0) surface were studied by the climbing-image nudged elastic band (CI-NEB) method. The calculation result shows that the more favorable dissociation energy barrier is about 0.406 eV. This indicates that the dissociation of H2O molecule on the surface of PuH2 (1 1 0) is favorable, even at room temperature.