Adsorption, dissociation and diffusion behavior of H 2 O on the PuO 2 (111) surface from DFT + U -D3: the role of hydrogen bonding.

The interaction between H2 O and plutonium oxide is an essential aspect of researching plutonium corrosion. We systematically studied the adsorption, dissociation, and diffusion of H2 O 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 H2 O molecules on the PuO2 (111) surface. When multiple H2 O molecules are adsorbed, hydrogen bonding between molecules can increase the average adsorption energy. H2 O 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 H2 O molecules. When the coverage of H2 O molecules is low, hydrogen bonds can significantly promote the adsorption and dissociation of H2 O molecules. And H2 O tends to exist on the surface of plutonium oxide in dissociated and molecular mixed states. The H atoms produced by the dissociation of H2 O 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.