Bubble pump consumption chronoamperometry for evaluating gas diffusion electrodes

Electrocatalytic gas consumption reactions (EGCRs), such as the oxygen reduction reaction (ORR) in fuel cells, are important half-cell reactions in electrochemical devices. The reactivity of active sites and gas diffusion kinetics are key to the performance of EGCRs; however, conventional characterization techniques can hardly give an accurate evaluation of the gas diffusion property and the structure features of gas diffusion electrodes (GDEs) under practical electrochemical working conditions. Here, we evolve a simple bubble pump consumption chronoamperometry (BPCC) method to evaluate the gas diffusion property of GDEs with ORR as a probe reaction via the real-time electrochemical response of a single-bubble injection. Two key parameters of GDE, diffusion coefficient and effective catalytic sites, can be extracted from the fitted diffusion-controlled reaction equation. Measurements of various GDEs under different working conditions demonstrate high accuracy and reliability of the BPCC method, making it a facile and promising evaluation standard for characterizing GDEs.