Enhanced electroanalysis in lithium potassium eutectic (LKE) using microfabricated square microelectrodes

Damion K. Corrigan, Ewen O. Blair, Jonathan G. Terry, Anthony J. Walton, Andrew R. Mount

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Molten salts (MSs) are an attractive medium for chemical and electrochemical processing and as a result there is demand for MS-compatible analysis technologies. However, MSs containing redox species present a challenging environment in which to perform analytical measurements because of their corrosive nature, significant thermal convection and the high temperatures involved. This paper outlines the fabrication and characterization of microfabricated square microelectrodes (MSMs) designed for electrochemical analysis in MS systems. Their design enables precise control over electrode dimension, the minimization of stress because of differential thermal expansion through design for high temperature operation, and the minimization of corrosive attack through effective insulation. The exemplar MS system used for characterization was lithium chloride/potassium chloride eutectic (LKE), which has potential applications in pyrochemical nuclear fuel reprocessing, metal refining, molten salt batteries and electric power cells. The observed responses for a range of redox ions between 400 and 500 °C (673 and 773 K) were quantitative and typical of microelectrodes. MSMs also showed the reduced iR drop, steady-state diffusion-limited response, and reduced sensitivity to convection seen for microelectrodes under ambient conditions and expected for these electrodes in comparison to macroelectrodes. Diffusion coefficients were obtained in close agreement with literature values, more readily and at greater precision and accuracy than both macroelectrode and previous microelectrode measurements. The feasibility of extracting individual physical parameters from mixtures of redox species (as required in reprocessing) and of the prolonged measurement required for online monitoring was also demonstrated. Together, this demonstrates that MSMs provide enhanced electrode devices widely applicable to the characterization of redox species in a range of MS systems.

Original languageEnglish
Pages (from-to)11342-11348
Number of pages7
JournalAnalytical Chemistry
Volume86
Issue number22
DOIs
Publication statusPublished - 18 Nov 2014

Keywords

  • molten salts
  • microelectrodes
  • lithium potassium eutectic

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