Enhancing the Stability of Acidic CO ₂ Reduction by Preventing OH ⁻ and Liquid Product Recirculation

ABSTRACT Acidic environments enhance CO ₂ utilization during CO ₂ electrolysis via a buffering effect that converts carbonates formed at the electrode surface back into CO ₂ . Nevertheless, further investigation into acidic CO ₂ electrolysis is required to improve its selectivity towards certain CO ₂ reduction reaction (CO ₂ RR) products, such as multicarbon (C ₂₊ ) 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 CO ₂ electrolysis at −600 mA cm ⁻² .