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化学学报
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化学学报 ›› 2006, Vol. 64 ›› Issue (4): 287-294. 上一篇    下一篇

研究论文

MnO2上氧气第一个电子转移步骤的从头计算研究

李莉1,2，魏子栋*, 1,3，李兰兰1,d，孙才新1   

  1. (1重庆大学高电压与电工新技术教育部重点实验室 重庆 400044)
    (2西华师范大学化学化工学院 南充 637002)
    (3重庆大学化学化工学院 重庆 400044)
    (4重庆大学材料科学与工程学院 重庆 400044)
  • 投稿日期:2005-06-21 修回日期:2005-10-08 发布日期:2006-02-28
  • 通讯作者: 魏子栋

Ab initio Study of the First Electron Transfer of O2 on MnO2 Surface

LI Li1,2, WEI Zi-Dong*,1,3, LI Lan-Lan1,4, SUN Cai-Xin1   

  1. (1 Key Laboratory of High Voltage Engineering and Electrical New Technology of the Ministry of Education,
    Chongqing University, Chongqing 400044)
    (2 School of Chemical Engineering, China West Normal University, Nanchong 637002)
    (3 School of Chemical Engineering, Chongqing University, Chongqing 400044)
    (4 School of Material Science and Engineering, Chongqing University, Chongqing 400044)
  • Received:2005-06-21 Revised:2005-10-08 Published:2006-02-28
  • Contact: WEI Zi-Dong

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采用裸露簇和嵌入簇模型, 对β-MnO2 (001), (110), (111)三个晶面以及O2在(110)晶面的单址吸附模式(Pauling和Griffths模式), 进行从头计算. 从β-MnO2 (001), (110), (111)三个晶面的电子结构差异以及O2在(110)晶面吸附的吸附能、几何结构、集居数以及净电荷数分析得到: (001), (110), (111)三个晶面中(110)晶面的催化活性最高, 其活性顺序为(110)＞(111)＞(001). 氧气在(110)晶面的吸附, Pauling和Griffths两种吸附模式均存在, 属于化学吸附中的离子吸附. 氧气与MnO2固体间发生了单电子转移, 氧气得到电子被还原成O2-, 转移电子属于整个体系, 具有离域性.

关键词: 氧还原, 金属空气电池, 二氧化锰, 电催化, 从头计算

The oxygen adsorption on MnO2 was studied in the light of quantum chemistry. The bare cluster of MnO2 with the size of Mn7O14 was employed to evaluate the difference in the frontier molecular orbital energy, Mulliken population and net charge of MnO2 three planes, (001), (110) and (111). The embedding cluster of Mn3O6＋Ca7＋1096PCs was used to study the oxygen adsorption on MnO2. Of three planes (001), (110) and (111) of MnO2, the plane (110) has the highest HOMO energy. And thus, it is the easiest for electrons to effuse from the plane (110) of MnO2 and transfer to O2. The catalytic activity of MnO2 to the first electron transfer of the oxygen reductive reaction (ORR) increases in the sequence of (001)＜(111)＜(110). The catalytic ability of MnO2 to the first electron transfer of the ORR was confirmed by the calculations of adsorption energy, O—O bond length, Mulliken overlap population, and net charge on the concerned atoms after O2 adsorption on MnO2. The adsorption energy evolved after O2 adsorption on MnO2 is much larger than that evolved in reaction O2＋e－→O2-. It suggests that MnO2 can strongly catalyze this reaction and thus more energy is evolved as it proceeds on MnO2. The electron-transfer from MnO2 to O2 is a process of delocalization, that is, the one transferred electron is not only from the Mn atom at adsorption site but also from the Mn atoms of the bulk MnO2 crystal cluster.

Key words: oxygen reduction reaction, metal-air battery, MnO2, electrocatalysis, ab initio