Acta Phys. -Chim. Sin. ›› 1992, Vol. 8 ›› Issue (03): 364 -369 .doi: 10.3866/PKU.WHXB19920315

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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

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