Importance of Time‐Dependent Wetting Behavior of Gas‐Diffusion Electrodes for Reactivity Determination.

Tin foil and SnOx/C gas‐diffusions electrodes (GDEs) were investigated via electrochemical impedance spectroscopy (EIS) to extract the differential double‐layer capacitance (Cdl) as a measure of the wetted surface area. Time‐dependent Cdl values revealed an immediate stationary wetting for tin foil electrodes while a distinct increase of Cdl – which becomes stationary with time – was observed for GDEs. The time‐dependent wetting behavior of the GDEs was substantiated by physical post‐mortem characterization. Since the wetted surface area determines the number of reachable active sites the performance of GDEs should be normalized to the wetted surface area for evaluation of reactivity. [ABSTRACT FROM AUTHOR]