Enhancing the Stability of Acidic CO₂ Reduction by Preventing OH⁻ and Liquid Product Recirculation

Acidic environments enhance CO2 utilization during CO2 electrolysis via a buffering effect that converts carbonates formed at the electrode surface back into CO2. Nevertheless, further investigation into acidic CO2 electrolysis is required to improve its selectivity towards certain CO2 reduction reaction (CO2RR) products, such as multicarbon (C2+) species, while enhancing its overall stability. In this study, liquid product recirculation in the catholyte and local OH− accumulation were identified as primary factors contributing to the degradation of gas diffusion electrodes mounted in closed‐loop catholyte configurations. We demonstrate that a single‐pass catholyte configuration prevents liquid product recirculation and maintains a continuous flow of acidic‐pH catholyte throughout the reaction while using the same volume as a closed‐loop setup. This approach improves electrode durability and maintains a Faradaic efficiency of 67% for multicarbon products over 4 h of CO2 electrolysis at −600 mA cm−2.