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

Abstract

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.

Keywords

acidic environment / CO2 reduction / electrocatalysis / multicarbon products / single-pass catholyte

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