物理化学学报 >> 2011, Vol. 27 >> Issue (10): 2319-2325.doi: 10.3866/PKU.WHXB20110936

理论与计算化学 上一篇    下一篇

CO2在α-U(001)表面的吸附和解离

李赣1, 罗文华1, 陈虎翅2   

  1. 1. 表面物理与化学重点实验室, 四川绵阳 621907;
    2. 中国工程物理研究院, 四川绵阳 621900
  • 收稿日期:2011-04-28 修回日期:2011-07-12 发布日期:2011-09-27
  • 通讯作者: 李赣 E-mail:2002ligan@sina.com
  • 基金资助:

    国防科技重点实验室基金(9140C6601010901)和中国工程物理研究院科学技术基金(2008A0301013)资助项目

Adsorption and Dissociation of CO2on the α-U(001) Surface

LI Gan1, LUO Wen-Hua1, CHEN Hu-Chi2   

  1. 1. Key Laboratory for Surface Physics and Chemistry, Mianyang 621907, Sichuan Province, P. R. China;
    2. China Academy of Engineering Physics, Mianyang 621900, Sichuan Province, P. R. China
  • Received:2011-04-28 Revised:2011-07-12 Published:2011-09-27
  • Contact: LI Gan E-mail:2002ligan@sina.com
  • Supported by:

    The project was supported by the Key Laboratory Foundation of Science and Technology of National Defense, China (9140C6601010901) and Science and Technology Foundation of China Academy of Engineering and Physics (2008A0301013).

摘要: 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 2πu/1πg/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.

关键词: 密度泛函理论, &, alpha, -U(001)表面, CO2分子, 吸附

Abstract: The adsorption and dissociation of CO2 on the α-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 α-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 α-U(001) surface. We found that CO2 strongly chemisorbed onto the α-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 2πu/1πg/3σu-U 6d orbital hybridization. The dissociative adsorption energies for the CO2 adsorbed on the hollow1 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.

Key words: Density functional theory, &, alpha, -U(001) surface, Carbon dioxide, Adsorption

MSC2000: 

  • O641