Adsorption, dissociation and diffusion behavior of H2O on the PuO2(111) surface from DFT + U-D3: the role of hydrogen bonding.

Abstract

The interaction between H2O and plutonium oxide is an essential aspect of researching plutonium corrosion. We systematically studied the adsorption, dissociation, and diffusion of H2O molecules on the PuO2(111) surface with the DFT + U-D3 scheme. We find that the top of the Pu atom is the most stable adsorption site for H2O molecules on the PuO2(111) surface. When multiple H2O molecules are adsorbed, hydrogen bonding between molecules can increase the average adsorption energy. H2O molecules will dissociate into H atoms and O-H groups under certain conditions. We have paid special attention to the role of hydrogen bonds between H2O molecules. When the coverage of H2O molecules is low, hydrogen bonds can significantly promote the adsorption and dissociation of H2O molecules. And H2O tends to exist on the surface of plutonium oxide in dissociated and molecular mixed states. The H atoms produced by the dissociation of H2O molecules are not easily diffused, which may be related to the hydrogen bonding between O-H groups. This work has important theoretical significance for deepening the understanding of the corrosion mechanism of plutonium.