First-principles study of co-adsorption behavior of O2and CO2molecules onδ-Pu(100)surface

First principles calculation is performed to study the co-adsorption behaviors of O₂and CO₂onδ-Pu(100)surface by using a slab model within the framework of density functional theory(DFT).The results demonstrate that the most favorable co-adsorption configurations are T_v-C₄O₇and T_p1-C₂O₈,with adsorption energy of-17.296 e V and-23.131 e V for CO₂-based and O₂-based system,respectively.The C and O atoms mainly interact with the Pu surface atoms.Furthermore,the chemical bonding between C/O and Pu atom is mainly of ionic state,and the reaction mechanism is that C 2 s,C 2 p,O 2s,and O 2p orbitals overlap and hybridize with Pu 6 p,Pu 6 d,and Pu 5 f orbital,resulting in the occurrence of new band structure.The adsorption and dissociation of CO₂molecule are obviously promoted by preferentially occupying adsorbed O atoms,therefore,a potential CO₂protection mechanism for plutonium-based materials is that in CO₂molecule there occurs complete dissociation of CO₂→C+O+O,then the dissociated C atom combines with O atom from O₂dissociation and produces CO,which will inhibit the O₂from further oxidizing Pu surface,and slow down the corrosion rate of plutoniumbased materials.