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Mechanistic insights into the potentiodynamic electrosynthesis of PEDOT thin films at a polarizable liquid|liquid interface
Date
2024
Abstract
Conducting polymer (CP) thin films find widespread use, for example in bioelectronic, energy harvesting and storage, and drug delivery technology. Electrosyn-thesis at a polarizable liquid|liquid interface using an aqueous oxidant and organic soluble monomer provides a route to free-standing and scalable CP thin films, such as poly(3,4- ethylenedioxythiophene) (PEDOT), in a single step at ambient conditions. Here, using the potentiodynamic technique of cyclic voltammetry, interfacial electrosynthesis involving ion exchange, electron transfer, and proton adsorption charge transfer processes is shown to be mechanistically distinct from CP electropolymerization at a solid electrode|electrolyte interface. During interfacial electrosynthesis, the applied interfacial Galvani potential difference controls the interfacial concentration of the oxidant, but not the CP redox state. Nevertheless, typical CP electropolymerization electrochemical behaviors, such as steady charge accumulation with each successive cycle and the appearance of a nucleation loop, were observed. By combining (spectro)electrochemical measurements and theoretical models, this work identifies the underlying mechanistic origin of each feature on the cyclic voltammograms (CVs) due to charge accumulated from Faradaic and capacitive processes as the PEDOT thin film grows. To prevent overoxidation during interfacial electrosynthesis with a powerful cerium aqueous oxidant, scan rates in excess 25 mV·s −1 were optimal. The experimental methodology and theoretical models outlined in this article provide a broadly generic framework to understand evolving CVs during interfacial electrosynthesis using any suitable oxidant/monomer combination
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Publisher
American Chemical Society
Citation
Journal of the American Chemical Society 146(42), pp. 28941–28951
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Funding Information
Irish Research Council (IRC) Government of Ireland Postdoctoral Fellowship Award (grant no. GOIPD/2018/252). A.G.-Q. also acknowledges funding received from the César Nombela Programme 2023 - Comunidad de Madrid (Project N°- 2023-T1/TEC 29227). R.A.L. acknowledges funding received from an IRC Government of Ireland Postgraduate scholarship (grant no. GOIPG/ 2018/2132). J.A.M. acknowledges the support from the Ministerio de Ciencia e Innovación (Spain) and the European Regional Development Funds (project PID2022-139953NBI00).
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Article
Rights
https://creativecommons.org/licenses/by-nc-sa/4.0/