Framework for Reliable Intrinsic Activity Assessment: Separating Electrical Double-Layer Capacitance and Pseudo-Capacitance in Iridium Oxide
Wonchul Park, Jongsu Noh, Hongmin An, Jooyoung Kim, Dong Young Chung
Abstract
Accurately quantifying the electrochemically active surface area (ECSA) of electrocatalysts is crucial for evaluating intrinsic activity but is often complicated by bulk contributions such as pseudocapacitance. In this study, we distinguish electrical double-layer (EDL) capacitance from pseudocapacitance in iridium oxide based on observations in the aprotic solvent where pseudocapacitance effects are isolated. We determine specific EDL capacitance (surface) values and discuss the contribution of pseudocapacitance (bulk) to the total capacitance in the aqueous solution. Our results highlight the significant impact of pseudocapacitance on total capacitance measurements and the importance of selecting appropriate normalization parameters for reliable intrinsic activity assessment. This work provides a reliable framework for accurately evaluating ECSA and intrinsic activity, offering insights into optimizing catalyst design and evaluating electrochemical performance.