The adsorption and dissociation of CO2 on the a-U(001) surface at 0.25 monolayer (ML) coverage was studied using density functional theory (DFT) within the generalized gradient approximation (GGA). Stable structures and corresponding energies of CO2 adsorbed on the a-U(001) surface were obtained while the transition state and corresponding energy barrier for CO2 dissociation was determined. We discussed the interaction mechanism between CO2 and the a-U(001) surface. We found that CO2 strongly chemisorbed onto the a-U(001) surface in a multi-bonding manner with adsorption energies of 1.24-1.67 eV and the degree of C - O bond activation depended on the degree of electron transfer from surface to the adsorbed CO. The interaction between the U atoms and the CO2 molecules mainly comes from the population of the CO2 2πu lowest unoccupied molecular orbital (LUMO) by U electrons with CO2 2tTu/1 7Tg/3σu-U 6d orbital hybridization. The dissociative adsorption energies for the CO2 adsorbed on the hollowl and hollow2 sites with three C-U bonds and six O-U bonds (H1-C3O6 and H2-C3O6) are 3.15 and 3.13 eV, respectively. The corresponding dissociation barriers are 0.26 and 0.36 eV, which indicates that the dissociation of adsorbed CO2 into CO and O occurs easily.%采用广义梯度密度泛函理论研究了0.25 ML覆盖度下CO2在α-U(001)表面上的吸附和解离,得到了CO2的稳定吸附构型和吸附能,确定了CO2的解离过渡态和解离能垒,探讨了CO2与表面U原子的相互作用本质.结果表明,CO2趋向以C(O)-U多键结合方式在α-U(001)面发生强化学吸附,吸附能为1.24-1.67 eV; C-O键的活化程度依赖于表面电子向CO2发生转移的程度.CO2与表面U原子的相互作用主要来自于U原子电子向CO2最低空轨道(LUMO)2πu转移,以及CO2 2π/1 πg/3σu-U 6d轨道间杂化而生成新的化学键.以形成3个C-U键和6个O-U键模式在穴位1和穴位2上发生吸附的CO2(H1-C3O6和H2-C3O6)的解离吸附能分别为3.15和3.13 eV,解离能垒分别为0.26和0.36 eV,预示着吸附CO2分子易于解离形成CO分子和O原子.
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