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Electrochemically controlled ion dynamics in porphyrin nanostructures

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journal contribution
posted on 2020-09-10, 13:19 authored by Andrés Molina-Osorio, José A. Manzanares, Alonso Gamero-Quijano, Micheál D. Scanlon
The dynamics of ion intercalation into solid matrices influences the performance of key components in most energy storage devices (Li-ion batteries, supercapacitors, fuel cells, etc.). Electrochemical methods provide key information on the thermodynamics and kinetics of these ion-transfer processes but are restricted to matrices supported on electronically conductive substrates. In this article, the electrified liquid|liquid interface is introduced as an ideal platform to probe the thermodynamics and kinetics of reversible ion intercalation with nonelectronically active matrices. Zinc(II) meso-tetrakis(4-carboxyphenyl)porphyrin nanostructures were self-assembled into floating films of ordered nanostructures at the water|α,α,α-trifluorotoluene interface. Electrochemically polarizing the aqueous phase negatively with respect to the organic phase led to organic ammonium cations intercalating into the zinc porphyrin nanostructures by binding to anionic carboxyl sites and displacing protons through ion exchange at neutral carboxyl sites. The cyclic voltammograms suggested a positive cooperativity mechanism for ion intercalation linked with structural rearrangements of the porphyrins within the nanostructures and were modeled using a Frumkin isotherm. The model also provided a robust understanding of the dependence of the voltammetry on the pH and organic electrolyte concentration. Kinetic analysis was performed using potential step chronoamperometry, with the current transients composed of “adsorption” and nucleation components. The latter were associated with domains within the nanostructures where, due to structural rearrangements, ion binding and exchange took place faster. This work opens opportunities to study the thermodynamics and kinetics of purely ionic ion intercalation reactions (not induced by redox reactions) in floating solid matrices using any desired electrochemical method.

Funding

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History

Publication

Journal of Physical Chemistry C;124 (33), pp. 18346-18355

Publisher

American Chemical Society

Note

peer-reviewed

Other Funding information

SFI, ERC, IRC

Rights

© 2020 ACS This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpcc.0c04976

Language

English

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