In-Operando Quantification of Electrode Flooding in CO₂ Electrolysis and Correlation to Product Distribution

Flooding of the gas diffusion electrode (GDE) is one of the most important failure mechanisms limiting the long-term stability of CO 2 electrolysis. Methods to characterize the GDE flooding process during the electrochemical reduction of CO 2 are essential in order to improve the understanding of this failure mechanism and to consequently accomplish a steady performance at industrially relevant operation conditions. Here, a method for in-operando quantification of GDE flooding is presented. By collecting and weighing the amount of electrolyte which leaked through the GDE of a flow cell electrolyzer, utilizing a water trap on a balance, a time-resolved correlation between flooding data and product distribution is obtained. To demonstrate its potential, the in-operando weighting is used to determine leakage rates under dynamic and static CO 2 electrolysis conditions and correlate them with the distribution of the gaseous reaction products. This new technique provides a deeper understanding of the dynamic processes behind GDE flooding during CO 2 electrolysis and its influence on the product distribution, enabling the development of novel mitigation strategies.