Dos and Dont’s in Determination of Electrochemical Kinetic Parameters of Reversible and Irreversible Redox couples using Cyclic Voltammetry

Cyclic voltammetry, as a versatile electroanalytical technique, is commonly utilized by researchers from various scientific disciplines to determine different kinetic parameters of a redox active species, including reversibility of a redox reaction, charge transfer coefficient (α), diffusion coefficient (D), formal electrode potential (Ef0), dimensionless kinetic parameter (ψ), and standard rate constant (k0) but systematic guidelines and best practices for accurate estimation of these parameters using the characteristic peak parameter expressions (peak potential, half peak potential, and peak current) of reversible and irreversible couple is currently lacking. Unfortunately a novice in this field is often confused and misguided by the controversial diagnostics of reversible and irreversible couples mentioned in many textbooks and literature. The lack of fundamental knowledge of voltammetry among researchers from different fields results in a buildup of misinterpreted kinetic data in the literature. This perspective explores the theoretical foundation, limitations, and challenges inherent in the existing voltammetry methodologies utilized for determining kinetic parameters. Corrections have been made to the disputed ψ and k0 values related to reversible and irreversible couples, along with the proposal of a new reference scale to accurately differentiate an irreversible couple. The determination of kinetic parameters using different peak parameter expressions of reversible and irreversible couples has been revised based on the ΔEP values. In addition, detailed instructions are provided for conducting accurate kinetic analysis of reversible and irreversible pairs, outlining what should and should not be done. This article aims to elucidate various concepts of cyclic voltammetry for novices, thereby dispelling any confusion found in the existing literature. It will provide a clear visualization of the application of peak parameter expressions for the accurate estimation of kinetic parameters as well as guidance on the correct execution of a cyclic voltammetry experiment. Additionally, an experimental module is included in the Supporting Information, which illustrates the process of conducting kinetic analysis using practical examples of redox couples.