A Tutorial on Measurement of Electrochemical Water-Splitting Performance Parameters: Methods and Best Practices

Electrochemical water splitting has emerged as a promising route to sustainable, green hydrogen production, playing a key role in advancing clean energy systems. The continued advancement of water electrolysis relies heavily on the rational design and evaluation of efficient, durable, and cost-effective electrocatalysts. However, a meaningful and fair comparison of electrocatalyst performance depends on accurate and standardized measurement protocols. This tutorial provides an in-depth overview of the best measurement practices for assessing performance parameters, including overpotential, Tafel slope, charge transfer, electrolyte resistance, electrochemical surface area, turnover frequency, stability, and Faradaic efficiency of electrocatalysts for water splitting. More emphasis is given on highlighting the strengths and limitations of various electrochemical methods, such as linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and chronopotentiometry (CP). Further, special attention is given to proper iR compensation, selection of appropriate scan rates, and identification of the non-Faradaic region for accurate determination of electrochemical surface area (ECSA). The role of redox peak integration in estimating active site densities, particularly for transition-metal-based electrocatalysts, is also a focus. The transition from standard three-electrode testing to a full-cell alkaline water electrolyzer is also discussed in detail, highlighting standard protocols to minimize the gap between lab-scale testing and commercial-scale electrolyzers. Thus, overall, this tutorial can be considered a practical guide for academicians and researchers, especially beginners in the field, aiming to enhance the reliability of electrochemical measurements and further catalyze the innovation and development of high-performance, energy-efficient water-splitting electrocatalysts for green hydrogen production.