Lehane Rob A, Gamero-Quijano Alonso, Manzanares José A, Scanlon Micheál D
The Bernal Institute and Department of Chemical Sciences, School of Natural Sciences, University of Limerick (UL), Limerick V94 T9PX, Ireland.
Instituto de Catálisis y Petroleoquímica - Consejo Superior de Investigaciones Científicas (ICP - CSIC), Calle de Marie Curie 2, Madrid 28049, Spain.
J Am Chem Soc. 2024 Oct 23;146(42):28941-28951. doi: 10.1021/jacs.4c09638. Epub 2024 Oct 8.
Conducting polymer (CP) thin films find widespread use, for example in bioelectronic, energy harvesting and storage, and drug delivery technology. Electrosynthesis 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 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.
导电聚合物（CP）薄膜有着广泛的应用，例如在生物电子学、能量收集与存储以及药物递送技术等领域。在可极化的液-液界面使用水性氧化剂和有机可溶性单体进行电合成，为在环境条件下一步制备独立且可扩展的CP薄膜，如聚（3,4-乙撑二氧噻吩）（PEDOT）提供了一条途径。在此，利用循环伏安法的动电位技术表明，涉及离子交换、电子转移和质子吸附电荷转移过程的界面电合成在机理上与固体电极-电解质界面处的CP电聚合不同。在界面电合成过程中，施加的界面伽伐尼电位差控制着氧化剂的界面浓度，但不控制CP的氧化还原状态。然而，仍观察到了典型的CP电聚合电化学行为，如每个连续循环中稳定的电荷积累以及成核环的出现。通过结合（光谱）电化学测量和理论模型，这项工作确定了随着PEDOT薄膜生长，由于法拉第和电容过程积累的电荷而在循环伏安图（CV）上每个特征的潜在机理起源。为了防止在使用强铈水性氧化剂进行界面电合成过程中发生过氧化，超过25 mV·s的扫描速率是最佳的。本文概述的实验方法和理论模型提供了一个广泛通用的框架，以理解使用任何合适的氧化剂/单体组合在界面电合成过程中不断变化的CV。
