Fluorescence-Based Observation of Transient Electrochemical and Electrokinetic Effects at Nanoconfined Bipolar Electrodes

Karen Scida, Alexander Eden, Netzahualcoyotl Arroyo-Curras, Sean Mackenzie, Yesil Satik, Carl D. Meinhart, Jan C.T. Eijkel, Sumita Pennathur

Research output: Contribution to journalArticle

Abstract

Bipolar electrodes (BPEs) are conductors that, when exposed to an electric field, polarize and promote the accumulation of counterionic charge near their poles. The rich physics of electrokinetic behavior near BPEs has not yet been rigorously studied, with our current understanding of such bipolar effects being restricted to steady-state conditions (under constant applied fields). Here, we reveal the dynamic electrokinetic and electrochemical phenomena that occur near nanoconfined BPEs throughout all stages of a reaction. Specifically, we demonstrate, both experimentally and through numerical modeling, that the removal of an electric field produces solution-phase charge imbalances in the vicinity of the BPE poles. These imbalances induce intense and short-lived nonequilibrium electric fields that drive the rapid transport of ions toward specific BPE locations. To determine the origin of these electrokinetic effects, we monitored the movement and fluorescent behavior (enhancement or quenching) of charged fluorophores within well-defined nanofluidic architectures via real-time optical detection. By systematically varying the nature of the fluorophore, the concentration of the electrolyte, the strength of the applied field, and oxide growth on the BPE surface, we dissect the ion transport events that occur in the aftermath of field-induced polarization. The results contained in this work provide new insights into transient bipolar electrokinetics that improve our understanding of current analytical platforms and can drive the development of new micro- and nanoelectrochemical systems.

Original languageEnglish (US)
Pages (from-to)13777-13786
Number of pages10
JournalACS Applied Materials and Interfaces
Volume11
Issue number14
DOIs
StatePublished - Apr 10 2019

Keywords

  • bipolar electrode
  • electric double layer
  • electrochemistry
  • electrokinetics
  • fluorescence
  • nanoconfinement
  • water electrolysis

ASJC Scopus subject areas

  • Materials Science(all)

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