Practical Aspects of Cyclic Voltammetry: How to Estimate Reduction Potentials When Irreversibility Prevails
Practical Aspects of Cyclic Voltammetry: How to Estimate Reduction Potentials When Irreversibility Prevails
复制标题
DOI：
10.1149/2.0241905jes
复制
发表时间：
2019-01-28
影响因子：
3.9
通讯作者：
Vullev, Valentine I.
中科院分区：
文献类型：
--
作者：
Espinoza, Eli M.;Clark, John A.;Vullev, Valentine I.
从表现出化学不可逆性的伏安图中估计标准电化学电位E-(0)的最佳方法是什么？大多数已知氧化还原物质的氧化或还原形式的寿命比伏安法获得的时间短得多，这导致了不可逆性，并使这个问题的答案变得至关重要。半波电位E-(1/2)提供了E-(0)的最佳实验表征。然而，由于不可逆氧化或还原，循环伏安图中缺乏阴极或阳极峰使得E-(1/2)无法获得。因此，我们评估从不可逆伏安图中容易获得的替代电位对E-(0)的估计有多接近。我们的分析表明，当E-(1/2)不可用时，拐点电位提供了氧化还原对的最佳表征。虽然峰电位是不可逆系统最广泛使用的描述符，但它们明显偏离E-(0)，特别是在高扫描速率下。即使对于部分不可逆体系，当阴极峰不如阳极峰明显时，半波电位仍然提供了E-(0)的最佳估计。这些发现的重要性超出了电化学和影响领域的范畴，如材料工程、光子学、细胞生物学、太阳能工程和神经科学，循环伏安法是这些领域的关键工具。(C)作者2019。由ECS出版。
What is the best approach for estimating standard electrochemical potentials, E-(0), from voltammograms that exhibit chemical irreversibility? The lifetimes of the oxidized or reduced forms of the majority of known redox species are considerably shorter than the voltammetry acquisition times, resulting in irreversibility and making the answer to this question of outmost importance. Half-wave potentials, E-(1/2), provide the best experimentally obtainable representation of E-(0). Due to irreversible oxidation or reduction, however, the lack of cathodic or anodic peaks in cyclic voltammograms renders E-(1/2) unattainable. Therefore, we evaluate how closely alternative potentials, readily obtainable from irreversible voltammograms, estimate E-(0). Our analysis reveals that, when E-(1/2) is not available, inflection-point potentials provide the best characterization of redox couples. While peak potentials are the most extensively used descriptor for irreversible systems, they deviate significantly from E-(0), especially at high scan rates. Even for partially irreversible systems, when the cathodic peak is not as pronounced as the anodic one, the half-wave potentials still provide the best estimates for E-(0). The importance of these findings extends beyond the realm of electrochemistry and impacts fields, such as materials engineering, photonics, cell biology, solar energy engineering and neuroscience, where cyclic voltammetry is a key tool. (C) The Author(s) 2019. Published by ECS.