物理化学学报 >> 1992, Vol. 8 >> Issue (03): 364-369.doi: 10.3866/PKU.WHXB19920315

研究论文 上一篇    下一篇

铁离子(II/III)/Nafion膜体系的阻抗分析

叶建辉   

  1. 厦门大学化学系,厦门 361005
  • 收稿日期:1991-02-27 修回日期:1991-08-18 发布日期:1992-06-15
  • 通讯作者: 叶建辉

Impedance Analysis of Fe(II/III) Ions/Nafion Film Coated Electrode System

Ye Jian-Hui   

  1. Department of Chemistry, Xiamen University, Xiamen 361005
  • Received:1991-02-27 Revised:1991-08-18 Published:1992-06-15
  • Contact: Ye Jian-Hui

摘要: 对Fe(Ⅱ/Ⅲ)离子在Nafion膜中的电荷传输以及在溶液扩散层中的传质过程进行了理论上的分析, 利用小幅度阶跃电位作为激励信号的阻抗测量法测定了该体系的阻抗并求出了Fe(Ⅱ/Ⅲ)离子在膜中的扩散系数和标准速度常数。同时讨论了电极电位和支持电解质浓度对体系阻抗的影响。实验的结果与理论推导的结果相一致。

关键词: Nafion膜, 铁离子, 电荷传输, 扩散, 阻抗测量

Abstract: The charge transport of Fe(Ⅱ/Ⅲ) ions within the Nafion film and in solutions has theoretically been derived. The diffusion coefficients and standard rate constants of Fe(Ⅱ/Ⅲ) ions in the film were evaluated to be 2.9×10~(-7) cm~2·s~(-1) and 1.1×10~(-3) cm·s~(-1), respectively, by analyzing the system impedance based on the small amplitude potential step. Obtained value of k°′ is less than an order of magnitude to uncoated electrodes, which is correlated with large diffusion rate of Fe(Ⅱ/Ⅲ) ions within the Nafion film. Effects of electrode potentials and concentrations of supporting electrolytes on the system impedances have been discussed. Results are reasonably agreed with theoretical derivations.

Key words: Nafion film, Iron ions, Charge transport, Diffusion, Impedance measurement