Investigation of rate-determining step of LaNi0.6Co0.4O3-δ film electrode

R. A. Budiman, Y. Uzumaki, S. Hashimoto, T. Nakamura, K. Yashiro, K. D. Bagarinao, H. Kishimoto, K. Yamaji, T. Horita, K. Amezawa, T. Kawada

Research output: Contribution to journalArticle

Abstract

The rate-determining step (RDS) in the oxygen reduction process on a LaNi0.6Co0.4O3-δ film electrode was analyzed using electrochemical impedance spectroscopy in varied temperatures (873–1073 K), oxygen partial pressures (1–10−3 bar), and DC bias. From the evaluation of the area-specific interfacial conductivity, σE, and chemical capacitance, CE, it is suggested that the RDS is surface reaction under low p(O2) (10−2–10−3 bar) but there appears a contribution of bulk diffusion under high p(O2) in the film electrode at any given temperature. The change of the RDS was also confirmed using isotope exchange depth profile method where a significant change in the oxygen profile in the film electrode was observed. This is attributed to the rate of the bulk diffusion of O2− which is almost constant when the oxygen nonstoichiometry of LaNi0.6Co0.4O3-δ is small, whereas the surface reaction rate strongly depends on p(O2). At low p(O2), the surface reaction is slower than the bulk diffusion, so that the potential drop on the surface of the electrode film is large. In contrast, at high p(O2), the surface reaction is faster than the bulk diffusion where the potential decay is sluggish inside the film electrode.

Original languageEnglish
Pages (from-to)2227-2235
Number of pages9
JournalJournal of Solid State Electrochemistry
Volume22
Issue number7
DOIs
Publication statusPublished - 2018 Jul 1

Keywords

  • Chemical capacitance
  • Film electrode
  • Isotope exchange
  • Rate-determining step

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Electrochemistry
  • Electrical and Electronic Engineering

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