Overcoming voltage issue in bicarbonate electrolysis: dual mass-transfer pathways for CO2 and ions

Abstract

The direct electrolysis of CO2-captured liquid, such as bicarbonate, offers economic advantages by eliminating the CO2 regeneration step. However, high cell voltages remain a major barrier. Herein, we propose a new strategy to build dual mass-transfer pathways for CO2 and ions using a carbon and anion exchange ionomer (AEI) to reduce cell voltages while achieving sufficient Faradaic efficiency (FE) for the CO2 reduction reaction. By optimizing the interposer materials and ratio of carbon, Ag, and AEI, sufficient FECO (57 %) and low cell voltages (3.17 V) were achieved at 100 mA cm-2 . The formation of dual masstransfer pathways in bicarbonate electrolysis was confirmed through in situ/operando visualization studies. To ensure stability, we recommend the generation of dual mass-transfer pathways using chemically and physically stable materials. Our work provides an understanding of the mass transfer in bicarbonate electrolysis and a direction for overcoming the voltage issue. (c) 2025 The Author(s). Published by Published by Elsevier B.V. and Science Press on behalf of Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).