The surface adsorption of hydride ions and hydrogen atoms on Zn studied by electrochemical impedance spectroscopy with a non-equilibrium thermodynamic formulation

Hironori Nakajima, Toshiyuki Nohira, Yasuhiko Ito, Signe Kjelstrup, Dick Bedeaux

研究成果: Contribution to journalArticle査読

7 被引用数 (Scopus)

抄録

We show that non-equilibrium thermodynamics theory for surfaces combined with electrochemical impedance spectroscopy can be used to derive the excess surface concentrations of reactants and products of an electrochemical reaction at an electrode. We predict the equivalent circuit for a postulated reaction using this theory, and derive expressions for the excess surface concentrations. The method is illustrated with experimental data for the following hydride reaction to hydrogen at a Zn anode in a molten eutectic mixture of LiCl and KCl at 673 K: The results support a two-step mechanism for hydrogen evolution via the hydrogen atom. We calculate the excess surface concentrations of the hydride ions and the hydrogen atoms at the metal surface, and find that the hydride ions cover a fraction of the surface while the hydrogen atoms are present in large excess. The excess surface concentration of the hydride ions varies largely with the polarized state of the surface, and so does its mean activity coefficient at the surface. The results contribute to a better understanding of the system in question. The method is general and is expected to give similar information for other electrodes.

本文言語英語
ページ(範囲)231-255
ページ数25
ジャーナルJournal of Non-Equilibrium Thermodynamics
31
3
DOI
出版ステータス出版済み - 9 1 2006
外部発表はい

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Physics and Astronomy(all)

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