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

Abstract

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.