物理化学学报 >> 2010, Vol. 26 >> Issue (10): 2659-2665.doi: 10.3866/PKU.WHXB20100934

电化学 上一篇    下一篇

外电场作用下水化聚全氟磺酸钾膜中水分子的电渗迁移

朱素华1,2,3,严六明2,纪晓波2,邵长乐2,陆文聪2   

  1. 1. 上海大学材料科学与工程学院,上海200444;
    2. 上海大学理学院化学系, 上海200444;
    3. 常熟理工学院物理与电子工程学院, 江苏常熟215500
  • 收稿日期:2010-04-29 修回日期:2010-06-14 发布日期:2010-09-27
  • 通讯作者: 严六明 E-mail:liuming.yan@shu.edu.cn
  • 基金资助:

    国家自然科学基金(20873081)和上海市科委纳米专项(0952nm01300)资助项目

Electroosmotic Drag of Water in Hydrated Potassium Perfluorosulfonated Polymer Membrane in External Electric Fields

ZHU Su-Hua1,2,3, YAN Liu-Ming2, JI Xiao-Bo2, SHAO Chang-Le2, LU Wen-Cong2   

  1. 1. College of Material Science and Engineering, Shanghai University, Shanghai 200444, P. R. China;
    2. Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, P. R. China;
    3. College of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500, Jiangsu Province, P. R. China
  • Received:2010-04-29 Revised:2010-06-14 Published:2010-09-27
  • Contact: YAN Liu-Ming E-mail:liuming.yan@shu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20873081), and the Nano project of Shanghai Municipal Science & Technology Commission, China (0952nm01300).

摘要:

用分子动力学模拟方法研究外电场(简称电场)作用下水化聚全氟磺酸钾膜中水分子的电渗迁移运动, 并分析探讨膜的结构与水分子的电渗迁移特性的关系. 结果表明, 无外加电场时水分子和K+的速度都服从麦克斯韦分布; 施加适当电场时, 水分子和K+在垂直电场方向上的速度分量仍服从麦克斯韦分布, 但平行电场方向上的速度分量则服从峰值漂移的麦克斯韦分布. 并且, 峰值漂移速度可作为水分子和K+的平均迁移速度的近似值, 从而计算得到水分子的电渗系数. 结果还显示,K+第一配位层内平均含有约4.04 个水分子, 它们的平均迁移速度只有K+的57%. 这部分水分子贡献的电渗迁移系数为总电渗迁移系数(2.97) 的77%.

关键词: 分子动力学模拟, 质子交换膜, 外电场, 电渗迁移, 速度分布函数

Abstract:

The electroosmotic drag and the corresponding mechanism of water molecules in hydrated potassiumperfluorosulfonate electrolyte polymer membrane were studied using molecular dynamics simulations, and therelationship between the membrane structure and electroosmotic drag characteristics was analyzed. It is concluded thatvelocities of both H2O and K+ obey the Maxwell velocity distribution function without external electric field applied. Ifan appropriate electric field is applied, the velocities of H2O and K+ still obey the Maxwell velocity distribution in thedirection perpendicular to the electric field, and obey the peak shifted Maxwell velocity distribution in the directionparallel to the electric field. The peak shifting velocities coincide with the average transport velocities of H2O and K+ induced by the applied electric field, and could be applied to evaluate the electroosmotic drag coefficient of water. Theresults also show that the average number of water molecules in the first coordination shell of K + is 4.04, and theaverage transport velocity of these water molecules is about 57% of that of K +. The electroosmotic drag coefficientcontributed by these water molecules is about 77% of total the electroosmotic drag coefficient(2.97) .

Key words: Molecular dynamics simulation, Proton exchange membrane, External electric field, Electroosmotic drag, Velocity distribution function

MSC2000: 

  • O646