Closed bipolar electrochemistry in a four-electrode configuration

Gamero‐Quijano, Alonso; Molina-Osorio, Andrés F.; Peljo, Pekka; Scanlon, Micheál D.

doi:10.1039/c9cp00774a

Cited by 27 publications

(25 citation statements)

References 72 publications

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“…1a(iii)). [26][27][28] Due to this autocatalytic effect, IET proceeds at a much lower overpotential than at a bare ITIES, with a higher kinetic rate. Thus, the PEDOT islands show rapid 2D growth, parallel to the L|L interface.…”

Section: The Mechanism Of Pedot Interfacial Electrosynthesismentioning

confidence: 99%

Electrosynthesis of Biocompatible Free-Standing PEDOT Thin Films at a Polarised Liquid|Liquid Interface

Lehane

Gamero‐Quijano

Malijauskaite

et al. 2021

Preprint

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The versatility of conducting polymers (CPs) facilitates their use in energy conversion and storage, sensor, and biomedical technologies, once processed into thin films. Hydrophobic CPs, like poly(3,4-ethylenedioxythiophene) (PEDOT), typically require the use of surfactant additives, such as poly(styrenesulfonate) (PSS), to aid their aqueous processability as thin films. However, excess PSS diminishes CP electrochemical performance, biocompatibility, and device stability. Here, we report the electrosynthesis of PEDOT thin films at a polarised liquid|liquid interface, a method non-reliant on conductive solid substrates that produces free-standing, additive-free, biocompatible, easily transferrable, and scalable 2D PEDOT thin films of any shape or size in a single-step at ambient conditions. We demonstrate the PEDOT thin film’s superior biocompatibility as scaffolds for cellular growth, opening immediate applications in organic electrochemical transistor (OECT) devices for monitoring cell behaviour over extended time periods, bio-scaffolds and medical devices, without the requirement for physiologically unstable and poorly biocompatible PSS.

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Section: The Mechanism Of Pedot Interfacial Electrosynthesismentioning

confidence: 99%

Electrosynthesis of Biocompatible Free-Standing PEDOT Thin Films at a Polarised Liquid|Liquid Interface

Lehane

Gamero‐Quijano

Malijauskaite

et al. 2021

Preprint

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“…However, in the 4-electrode CBPEC with immiscible aqueous-organic solutions, the peak on the forward sweep with a positive current indicates the flow of negative charge, i.e., electrons, from the organic to aqueous compartment through the progress of two half-reactions [9]. As outlined in eqn ( 1) and (2), simultaneously, an aqueous electron acceptor species (Aw) is reduced at Pw and an organic electron donor species (Do) is oxidised at Po.…”

Section: Interpreting Voltammetry In a 4-electrode Cbpec Experimentsmentioning

confidence: 99%

“…Furthermore, as observed using the smaller potential window in section 3.5, the potential variation on the reductively pre-treated Pw was more wide-ranging, changing by a substantial 787 mV compared with the 372 mV experienced by the oxidatively pre-treated Pw. The bipolar electrode in the 4-electrode CBPEC is an equipotential body and is typically considered to have a floating potential along Pw and Po [9]. However, for the experiments described herein, the fact that the potential window on Pw barely changed after oxidative pretreatment when applying the short potential window (-0.600 to +0.200 V), means that "the floating potential" concept is not an entirely accurate description in this case.…”

Section: Electrode Cbpecmentioning

confidence: 99%

“…To optimise the potential applied to each driving electrode, in order to precisely tune the interfacial potential difference between the bipolar electrode and solution, reference electrodes may also be introduced into each electrolyte. This is known as a CBPEC in a 4-electrode configuration and may conceptually be compared to two back-to-back 3-electrode electrochemical cells connected by a conducting electronic bridge, i.e., the bipolar electrode [9]. The opposite poles of the bipolar electrode are effectively working electrodes in each electrolyte, with the driving electrodes operating as the counter electrodes.…”

Section: Introductionmentioning

confidence: 99%

“…The interpretation of voltammetry for a 4-electrode CBPEC is non-trivial as the electrochemical features are determined by thermodynamic and kinetic factors that influence the redox processes at both poles of the bipolar electrode simultaneously [9]. The bipolar electrode is not simply an electron conductor between the two electrolytes, its surface may contain redox active functional groups that influence the voltammetryjust as the surface chemistry of any working electrode influences the voltammetry observed in a conventional 3electrode cell.…”

Section: Introductionmentioning

confidence: 99%

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Aqueous surface chemistry of gold mesh electrodes in a closed bipolar electrochemical cell

Gamero‐Quijano

Herzog

Scanlon

2020

Electrochimica Acta

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The influence of the bipolar electrode on the voltammetry observed with a closed bipolar electrochemical cell (CBPEC) goes far beyond simply conducting electrons between the two electrolyte solutions. The surface of each pole of the bipolar electrode may contain redox active functional groups that generate misleading or interfering electrochemical responses. Herein, a 4-electrode CBPEC configuration was studied with the opposite poles of the bipolar electrode resting in separate aqueous and organic electrolyte solutions. Using gold mesh wire electrodes as the poles, we systematically investigated the many experimental variables that influence the observed voltammetry upon addition of a reductant (decamethylferrocene) to the organic phase. External bias of the driving electrodes forced electrons released by decamethylferrocene at the organic pole to flow along the bipolar electrode and reduce redox active surface functional groups at the aqueous pole, such as oxide or hydroxide groups, or carry out the oxygen reduction reaction (ORR) or hydrogen evolution reaction (HER). The 4-electrode CBPEC configuration diminishes capacitive currents, permitting observation of voltammetric signals from electron transfer processes related to surface functional groups at the aqueous pole at much lower scan rates than possible with working electrodes in conventional 3-electrode electrochemical cells. Surface modification, by oxidative or reductive electrochemical pretreatment, changes the potential window experienced by the aqueous pole in the 4-electrode CBPEC in terms of its position versus the standard hydrogen electrode (SHE) and dynamic range. In a related observation, the electrochemical responses from the surface functional groups on the aqueous pole completely disappear after oxidative pre-treatment, but remain after reductive pre-treatment. The flow of electrons from decamethylferrocene to the surface of the aqueous pole is limited in magnitude, by the decamethylferrocene concentration, and kinetically limited, due to decamethylferrocene diffusion to the organic pole, in comparison to the infinite supply of electrons delivered to the surface of a working electrode in a 3-electrode cell. This unique feature of the 4-electrode CBPEC facilitates a very gradual evolution of the surface chemistry at the aqueous pole, for example from fully oxidised after oxidative pretreatment to a more reduced state after repetitive cyclic voltammetry cycling. Perspective applications of this slow, controlled release of electrons to the electrode surface include spectroelectrochemical analysis of intermediate states for the reduction of metal salts to nanoparticles, or conversion of CO2 to reduced products at catalytic sites. The use of indium tin oxide (ITO) electrodes in CBPEC experiments for specific reactions is recommended to avoid misleading or interfering electrochemical responses from redox active functional groups prevalent on metallic surfaces. However, the electronic bridge to implement entirely depends on the reaction under study,...

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2024

Nanotechnologies and Nanomaterials Applied to Chemical Sensors and Biosensors

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Closed bipolar electrochemistry in a four-electrode configuration

Abstract: The thermodynamic theory underpinning closed bipolar electrochemistry in a 4-electrode configuration is presented; a technique applicable to spectro-electroanalysis, energy storage, electrocatalysis and electrodeposition.

Cited by 27 publications

References 72 publications

Electrosynthesis of Biocompatible Free-Standing PEDOT Thin Films at a Polarised Liquid|Liquid Interface

Electrosynthesis of Biocompatible Free-Standing PEDOT Thin Films at a Polarised Liquid|Liquid Interface

Aqueous surface chemistry of gold mesh electrodes in a closed bipolar electrochemical cell

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