Study on Adsorption Behavior of CO2 on the δ-Pu(100) Sur-face Based on First-principles

Abstract:

A first-principles calculation was applied to study the adsorption behavior of CO₂ on δ-Pu(100) surface using a slab model within the framework of density functional theory. Results demonstrate that CO₂ molecules are adsorbed on δ-Pu(100) surface at C-terminated bent state by multi-bond binding of C-Pu and O-Pu. The adsorption type belongs to strong chemical adsorption and the most stable adsorption configuration is H₁-C₄O₄ with the adsorption energy of -6.430 eV. The adsorption stability order is hollow site>bridge site>top site. CO₂ molecule mainly interacts with Pu surface atoms, while the interaction with other three Pu atoms is weak. The transfer of more electrons to the CO₂ 2π_u orbital is beneficial to the bending and activation of C-O bonds. Moreover, the chemical bonding between Pu atoms and CO₂ molecule is mainly ionic state and the reaction mechanism is that the C 2s, C 2p, O 2s and O 2p orbitals of CO₂ molecule hybrid with Pu 6p, Pu 6d and Pu 5f orbitals, resulting in a new bond structure. The work function of the H₁-C₄O₄ site changes the least, indicating that other electrons readily escape from the metal surface and the required energy is the smallest.