TY - JOUR
T1 - Fluorescence-Based Observation of Transient Electrochemical and Electrokinetic Effects at Nanoconfined Bipolar Electrodes
AU - Scida, Karen
AU - Eden, Alexander
AU - Arroyo-Currás, Netzahualcóyotl
AU - Mackenzie, Sean
AU - Satik, Yesil
AU - Meinhart, Carl D.
AU - Eijkel, Jan C.T.
AU - Pennathur, Sumita
N1 - Funding Information:
The authors would like to thank Dr. L. Garner for helpful discussions regarding the fluorophores, Dr. B. N. Queenan for valuable contributions to the manuscript, and acknowledge the use of the Microfluidics Laboratory within the California NanoSystems Institute, supported by the University of California Santa Barbara and the University of California, Office of the President. Some of the work was performed at the UCSB Nanofabrication Facility. K.S. was supported by the Otis Williams Postdoctoral Fellowship from the Santa Barbara Foundation.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/4/10
Y1 - 2019/4/10
N2 - 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.
AB - 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.
KW - bipolar electrode
KW - electric double layer
KW - electrochemistry
KW - electrokinetics
KW - fluorescence
KW - nanoconfinement
KW - water electrolysis
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U2 - 10.1021/acsami.9b01339
DO - 10.1021/acsami.9b01339
M3 - Article
C2 - 30880379
AN - SCOPUS:85064201739
SN - 1944-8244
VL - 11
SP - 13777
EP - 13786
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 14
ER -