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

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dc.contributor.author Gamero-Quijano, Alonso
dc.contributor.author Herzog, Grégoire
dc.contributor.author Scanlon, Micheál D.
dc.date.accessioned 2020-01-14T15:01:23Z
dc.date.issued 2020
dc.identifier.issn 0013-4686
dc.identifier.uri http://hdl.handle.net/10344/8372
dc.description peer-reviewed en_US
dc.description The full text of this article will not be available in ULIR until the embargo expires on the 18/11/2021
dc.description.abstract 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 pre-treatment, 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 pre-treatment 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, as ITO also has drawbacks such as a lack of electrocatalytic activity and the requirement of an overpotential due to its semiconducting nature. en_US
dc.language.iso eng en_US
dc.publisher Elsevier en_US
dc.relation 716792 en_US
dc.relation.ispartofseries Electrochimica Acta;330, 135328
dc.relation.uri https://www.sciencedirect.com/science/article/pii/S0013468619322005
dc.relation.uri http://dx.doi.org/10.1016/j.electacta.2019.135328
dc.rights This is the author’s version of a work that was accepted for publication in Electrochimica Acta. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Electrochimica Acta, 330, 135328, http://dx.doi.org/10.1016/j.electacta.2019.135328 en_US
dc.subject Bipolar electrochemistry en_US
dc.subject Bipolar electrode en_US
dc.subject Hydrogen evolution reaction en_US
dc.subject Oxygen reduction reaction en_US
dc.subject Redox active surface functional groups en_US
dc.title Aqueous surface chemistry of gold mesh electrodes in a closed bipolar electrochemical cell en_US
dc.type info:eu-repo/semantics/article en_US
dc.type.supercollection all_ul_research en_US
dc.type.supercollection ul_published_reviewed en_US
dc.date.updated 2020-01-10T15:33:13Z
dc.description.version ACCEPTED
dc.identifier.doi 10.1016/j.electacta.2019.135328
dc.contributor.sponsor ERC en_US
dc.contributor.sponsor SFI en_US
dc.contributor.sponsor Agence Nationale en_US
dc.relation.projectid 716792 en_US
dc.relation.projectid 13/SIRG/2137 en_US
dc.relation.projectid GOIPD/2018/252 en_US
dc.relation.projectid ANR-14-CE14-002-10 en_US
dc.date.embargoEndDate 2021-11-18
dc.embargo.terms 2021-11-18 en_US
dc.rights.accessrights info:eu-repo/semantics/embargoedAccess en_US
dc.internal.rssid 2936757
dc.internal.copyrightchecked Yes
dc.identifier.journaltitle Electrochimica Acta
dc.description.status peer-reviewed


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