Understanding degradation phenomena in high-performing polymer-based gas diffusion electrodes for electrochemical CO2 reduction

Electrochemical CO2 reduction (eCO2R) powered by renewable electricity can convert detrimental CO2 emissions into sustainable fuels and chemicals. By using gas diffusion electrodes (GDEs) and by reacting CO2 from the gas phase, high eCO2R current density can be achieved. GDEs, however, degrade fast during eCO2R due to flooding by the electrolyte, thus operating for < 100 h. Flooding can be curbed in polymer GDEs using hydrophobic substrates, but it can still be induced by precipitation of hygroscopic carbonate crystals in the GDE due to CO2 dissolution. In our previous work, polymer GDEs of small pore size were 50x more stable than their large pore size counterpart (< 1 h to > 50 h). We thus propose to use operando XRD in Beamline ID31 to study carbonate precipitation during eCO2R, its kinetics and its dependence on GDE pore size. As GDE degradation is the most severe issue facing eCO2R, these results will provide fundamental understanding as well as important technological guidelines.