物理化学学报 >> 2015, Vol. 31 >> Issue (3): 425-434.doi: 10.3866/PKU.WHXB201501191

理论与计算化学 上一篇    下一篇

纳米团簇Au19Pd和Au19Pt催化解离N2O

俞炜铃1, 左会文1, 陆春海2, 李奕1, 章永凡1, 陈文凯1   

  1. 1. 福州大学化学系, 福州 350116;
    2. 成都理工大学核技术与自动化工程学院, 成都 610059
  • 收稿日期:2014-11-13 修回日期:2015-01-19 发布日期:2015-03-06
  • 通讯作者: 陆春海, 陈文凯 E-mail:luchhi@126.com;wkchen@fzu.edu.cn
  • 基金资助:

    国家自然科学基金(21203027)和福建省自然科学基金(2012J01041)资助项目

Nitrous Oxide Decomposition Catalyzed by Au19Pd and Au19Pt Clusters

YU Wei-Ling1, ZUO Hui-Wen1, LU Chun-Hai2, LI Yi1, ZHANG Yong-Fan1, CHEN Wen-Kai1   

  1. 1. Department of Chemistry, Fuzhou University, Fuzhou 350116, P. R. China;
    2. College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu 610059, P. R. China
  • Received:2014-11-13 Revised:2015-01-19 Published:2015-03-06
  • Contact: LU Chun-Hai, CHEN Wen-Kai E-mail:luchhi@126.com;wkchen@fzu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21203027) and Fujian Provincial Natural Science Foundation, China (2012J01041).

摘要:

采用密度泛函理论研究Au-Pd和Au-Pt 纳米团簇催化解离N2O. 首先根据计算得到Au19Pd和Au19Pt 团簇的最优构型(杂原子均位于团簇的表面). 以Au19Pd催化解离N2O为例研究催化解离的反应机理. 对此主要考虑两个反应机理, 分别是Eley-Rideal (ER)和Langmuir-Hinshelwood (LH). 第一个机理中N2O解离的能垒是1.118 eV, 并且放热0.371 eV. N2分子脱附后, 表面剩余的氧原子沿着ER路径消除需要克服的能垒是1.920eV, 这比反应沿着LH路径的能垒高0.251 eV. 此外根据LH机理, 氧原子在表面的吸附能是-3.203 eV, 而氧原子在表面转移所需的能垒是0.113 eV, 这表明氧原子十分容易在团簇表面转移, 从而促进氧气分子的生成. 因此, LH为最优反应路径. 为了比较Au19Pd和Au19Pt 对N2O解离的活性, 根据最优的反应路径来研究Au19Pt 催化解离N2O, 得到作为铂族元素的铂和钯对N2O的解离有催化活性, 尤其是钯. 同时, 将团簇与文献中的Au-Pd合金相比较, 得到这两种团簇对N2O 解离有较高的活性, 尤其是Au19Pd团簇. 再者, O2的脱附不再是影响反应的主要原因, 这可以进一步提高团簇解离N2O的活性.

关键词: 纳米团簇, 催化活性, N2O解离, 反应机理

Abstract:

The catalytic decomposition of N2O using Au19Pd and Au19Pt clusters as catalysts with optimized geometries was studied using density functional theory (DFT). The optimized geometries of the Au19Pd and Au19Pt clusters were obtained as a function of structural and thermodynamic analyses, in which the heteroatoms are on the surfaces of the clusters. We selected the Au19Pd cluster as a model cluster to investigate the reaction mechanism of N2O decomposition. There are two reaction pathways to be considered: Eley-Rideal (ER) and Langmuir-Hinshelwood (LH). We found that the first N2O decomposition needs to surmount an energy barrier of 1.118 eV, and is exothermic by 0.371 eV. The elimination of the residual oxygen atom on the surface has an energy barrier of 1.920 eV along the ER pathway after N2 desorption, which is higher than that along the LH channel (1.669 eV). The adsorption energy of the oxygen atom on the surface is -3.203 eV, and the oxygen atom diffusion on the surface needs to surmount an energy barrier of 0.113 eV along the LH pathway. This indicates that the oxygen atom is prone to transfer on the cluster to promote the generation of the O2 molecule, and therefore the LH is the optimized reaction pathway. We investigated the catalytic activity of Au19Pt for N2O decomposition along the LH pathway in comparison with the Au19Pd cluster. Both platinum and palladium have catalytic activities for N2O decomposition, especially the palladium in this study. Comparison between this work and the theoretical study on periodic systems shows that these two clusters can be used as better catalysts for N2O decomposition, especially the Au19Pd cluster. Furthermore, the O2 desorption is no longer the main barrier to the reaction, which further enhances the catalytic activities of these two clusters for N2O decomposition.

Key words: Nanocluster, Catalytic activity, N2O decomposition, Reaction mechanism

MSC2000: 

  • O641