Decoupling Variable Capacitance and Diffusive Components of Active Solid–Liquid Interfaces with Flex Points

Abstract

Understanding the current transport characteristics of electrode interfaces is essential for optimizing device performance across a wide range of applications including bio-/chemical sensing and energy storage sectors. Cyclic voltammetry (CV) is a popular method for studying interfacial properties, particularly those involving redox systems. However, it remains challenging to differentiate between electron movements that contribute to capacitive and diffusive behaviors. In this study, we introduce a technique called flex point analysis, which uses a single differentiation step to separate capacitive and diffusive electron movements at the electrode interface during a redox reaction. Our results show that the variable capacitance at the electrode surface exhibited both positive and negative values on the order of 10^–6 (micro) Farad. This approach provides a clearer understanding of interfacial electron dynamics, enhancing the interpretation of CV data and potentially improving the design and optimization of related materials and devices.