Adsorption and dissociation behavior of H2O on PuH2 (110) surface: A density functional theory study

Highlights: • The adsorption of H₂O molecule on the surface of PuH₂ (1 1 0) basically presents chemical adsorption. • The adsorption direction of H₂O molecule parallel to the PuH₂ (1 1 0) surface preferentially on the top of Pu atom. • The vibration frequencies results of the adsorbed H₂O molecule show a red shift phenomenon in the absorbed H₂O molecule. • The climbing-image nudged elastic band (CI-NEB) results show the dissociation of H₂O on the surface of PuH₂(1 1 0) is a hydroxylation process with dissociation energy barrier 0.406eV, forming hydroxide of plutonium on the surface. 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.