Embedded Cluster Study of the Co-Adsorption of HCl and H2O on PuO2 Surfaces

The simultaneous adsorption of HCl and H2O on the {111} and {110} surfaces of PuO2 has been studied using hybrid density functional theory within the periodic electrostatic embedded cluster method. A synergistic effect between co-adsorbed molecules is identified, such that HCl binding energies are enhanced by the presence of water. Higher levels of water also increase the HCl binding energy, forming very stable configurations on both surfaces for first-layer HCl interactions. Second-layer interactions are also explored, in which the HCl molecule is placed above a full monolayer of water on the surfaces. In such circumstances, the HCl reacts with a hydroxyl from the water monolayer to produce molecular water, with the chloride held to the surface via numerous chlorine-acceptor hydrogen bonds.