Electrokinetic Streaming-Current Methods to Probe the Electrode-Electrolyte Interface under Applied Potentials

Prantik Saha, Changwoo Nam, Michael A. Hickner, Iryna V. Zenyuk

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

At an electrified interface of metal and electrolyte, ion concentration in the diffuse layer is different from the bulk and is impacted by metal charge. The double-layer structure can significantly enhance local ionic conductivity. Understanding the conductivity enhancement with conventional electrochemical measurements is challenging; however, electrokinetic experiments can be more useful in probing local ionic conductivities. We used streaming-current experiments for a range of pH values to measure ζ-potential at metal-electrolyte interfaces. We extend the method by incorporating a three-electrode electrochemical cell where the potential of the metal can be varied. By using a range of applied potentials between -200 and 800 mV (vs standard hydrogen electrode), we explored how surface charging of Au electrode affects ζ-potential. An inflection point is observed on the plot of ζ-potential against applied potential, and this point is believed to be a potential of zero charge of the electrode. Using the Gouy-Chapman-Stern-Grahame model, we correlate measured ζ-potential values to metal surface charge and calculate ionic distribution and conductivity within the microchannel. Finally, ionic conductivity is calculated as a function of metal surface charge, and as expected, Gouy-Chapman theory shows a parabolic relationship.

Original languageEnglish (US)
Pages (from-to)19493-19505
Number of pages13
JournalJournal of Physical Chemistry C
Volume123
Issue number32
DOIs
StatePublished - Aug 15 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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