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We investigate the emergence of current oscillations of a bipolar electrode (BPE) in coupled anode/cathode reaction under potentiostatic condition. In a traditional three-electrode setup, the nickel dissolution in sulfuric acid requires a minimum amount of IR ohmic drop, and thus series resistance for the oscillations to occur. In this paper, it is shown that in bipolar setup, when the nickel electrodissolution on the anodic side is coupled to hydrogen ion reduction on the cathodic side, spontaneous current oscillations can occur. An electrochemical analysis of the dynamics shows that the required circuit potential for the oscillations can be predicted from estimating the overpotentials needed for the anodic and cathodic reactions, the driving electrode, and the ohmic drop in the electrolyte. The dynamics and range of oscillations can be tuned by different concentrations of electrolyte, on both the anodic and the cathodic sides. In the considered example, the charge transfer resistance of the cathodic reaction can provide sufficient total resistance even when the solution resistance does not yield sufficient IR drop for the oscillations. Our findings have the potential to promote further studies of the collective behavior of electrochemical reactions using multielectrode arrays in bipolar electrode setups.
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Synchronization of two electrochemical oscillators in a closed bipolar cell
We investigate the dynamical behavior of the oscillatory electrodissolution of nickel and hydrogen reduction reaction in a closed electrochemical bipolar cell with two nickel wires. In the bipolar setup, two-half U cells are separated by an epoxy plate with the two embedded nickel electrodes; the oxidation and reduction reactions take place at the two ends of the same wire. The electrode potential oscillations were found to be strongly synchronized with 1 mm diameter electrodes in an in-phase configuration. Because experiments in similar configurations with traditional (three-electrode) cell showed no synchronization of the oscillatory anodic nickel electrodissolution, the introduction of the cathodic side of the bipolar electrodes induced the synchronization. The results were interpreted with a model that considered the kinetically coupled cathode-anode dynamics as well as interactions on the cathode and the anode side through migration current mediated potential drops in the electrolyte. The electrical coupling strength was calculated from solution resistance and charge transfer resistance measurements. The theory correctly interpreted that the bipolar cell with large (1 mm diameter) electrodes exhibits strong coupling with synchronization, and the bipolar cell with small (0.25 mm diameter) electrodes and the traditional configuration exhibit weak coupling and thus desynchronization. The experiments demonstrate the use of bipolar electrochemical cells for the investigation of collective behavior of electrochemical processes and the proposed approach holds promise for the design of bipolar multi-electrode arrays with engineered coupling to promote sensing and information processing using microchips.
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- Award ID(s):
- 1900011
- PAR ID:
- 10557366
- Publisher / Repository:
- Frontiers
- Date Published:
- Journal Name:
- Frontiers in Complex Systems
- Volume:
- 2
- ISSN:
- 2813-6187
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fcpxs.2024.1397573
