Seven steps to reliable cyclic voltammetry measurements for the determination of double layer capacitance

TL;DR

This paper introduces a comprehensive seven-step protocol for reliably measuring double layer capacitance via cyclic voltammetry, emphasizing measurement settings, data collection, and processing to improve accuracy in electrochemical analysis.

Contribution

It presents a novel, detailed seven-step method for consistent CDL determination and advocates for allometric regression over linear regression, enhancing the reliability of voltammetric measurements.

Findings

Neglecting key procedural aspects causes up to 61% deviation in results.

Allometric regression outperforms linear regression for CDL estimation.

The method improves accuracy and can be applied to various voltammetric analyses.

Abstract

Discovery of electrocatalytic materials for high-performance energy conversion and storage applications relies on the adequate characterization of their intrinsic activity, which is currently hindered by the dearth of a protocol for consistent and precise determination of double layer capacitance (CDL). Herein, we propose a seven-step method that aims to determine CDL reliably by scan rate-dependent cyclic voltammetry. The method considers three aspects that strongly influence the outcome of the analysis: measurement settings, data collection, and data processing. To illustrate the proposed method, two systems were studied: a resistor-capacitor electric circuit and a glassy carbon disk in an electrochemical cell. With these studies it is demonstrated that when any of the mentioned aspects of the procedure are neglected, substantial deviations of the results are observed with misestimations as large as 61% in the case of the investigated electrochemical system. Moreover, we propose allometric regression as a more suitable model than linear regression for the determination of CDL for both the ideal and the non-ideal systems investigated. We stress the importance of assessing the accuracy of not only highly specialized electrochemical methods, but also of those that are well-known and commonly used as it is the case of the voltammetric methods. The methodology proposed herein is not limited to the determination of CDL, but can be effectively applied to any other voltammetry-based analysis that aims to deliver quantitative results.