| Autor: |
Pendergast AD; Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States., Gutierrez-Portocarrero S; Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States., Noriega R; Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States., White HS; Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2024 Nov 06; Vol. 146 (44), pp. 30464-30473. Date of Electronic Publication: 2024 Oct 28. |
| DOI: |
10.1021/jacs.4c11180 |
| Abstrakt: |
A mechanism for the concerted pathway of coupled electron- and phase-transfer reactions (CEPhT) is proposed. CEPhT at three-phase interfaces formed by a solid electrode, an insulating organic solvent, and an aqueous electrolyte is driven by electric double layer (EDL) spillover, with significant electrostatic potential gradients extending a few nanometers into the insulating phase. This EDL spillover phenomenon is studied using scanning electrochemical cell microscopy to interrogate the oxidation of ferrocene in toluene to ferrocenium in water, (Fc) tol → (Fc + ) aq + e - . Finite element method simulations of the electrostatic potential distribution and species concentration profiles enable the calculation of complete i - E curves that incorporate mass transport, electron transfer, phase transfer, and the EDL structure. Simulated and experimental i - E traces show good agreement in the current magnitude and the effect of the supporting electrolyte, identifying an unexpected dependence of overall reaction kinetics on the concentration of the supporting electrolyte in the aqueous phase due to EDL spillover. An interfacial toluene/water mixing region generates a unique electrochemical microenvironment where concerted electron transfer and solvent shell replacement facilitate CEPhT. Kinetic expressions for concerted and sequential CEPhT mechanisms highlight the role of this interfacial environment in controlling the rate of CEPhT. These combined experimental and simulated results are the first to support a concerted mechanism for CEPhT where (Fc) tol is transported to the interfacial mixing region at the three-phase interface, where it undergoes oxidation and phase transfer. EDL spillover can be leveraged for engineering sample geometries and electrostatic microenvironments to drive electrochemical reactivity in classically forbidden regions, e.g., insulating solvents and gases. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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