Method—Best Practices and Common Pitfalls in Experimental Investigation of Electrochemical CO₂ Reduction at Gas Diffusion Electrodes

Gas diffusion electrodes (GDEs) play a crucial role in the development of electrochemical CO₂ reduction (eCO₂R) toward an economically viable process. While membrane electrode assemblies (MEAs) are currently the most efficient approach due to their low cell voltage, electrolyte supported GDEs still present a valuable tool for the characterization of catalysts under industrially relevant current densities, allowing for direct measurement of the electrode potential against reference electrodes. In this study, common experimental methods of iR correction and pressure control in eCO₂R literature studies on GDEs are analyzed and compared regarding their potential impact on the reported results. It is revealed that failure to account for dynamic changes in iR-drop can lead to significant inaccuracies in reported electrode potentials. Additionally, common methods for the application of differential pressure across GDEs are shown to impact the performance, leading to additional errors in experimental results. Based on these findings, an experimental protocol for the application of single high frequency response as a method for iR correction is developed, providing a tool for reproducible electrochemical characterization of GDEs in eCO₂R.