Interaction of Cathode Interface Microenvironment and Anode Electrolyte in Zero-Gap Electrolyzer for CO2 Conversion

The electrocatalytic conversion of carbon dioxide into fuels and chemicals using renewable energy holds tremendous promise as a viable solution for mitigating CO2 and storing intermittent renewable resources. While considerable researches have explored catalysts for CO2 reduction, opportunities remain to improve the efficiency and selectivity of the electrochemical conversion through tailored electrode and electrolyzer designs. Herein, we investigated the impact of anode electrolyte on the cathode interfacial microenvironment in zero-gap electrolytic cells for carbon dioxide reduction by employing two customized cathode electrode preparation technologies. It was found that due to variances in interfacial resistance caused by the interfacial differences, the catalyst-coated membrane (CCM) exhibited superior performance when the anode electrolyte was pure water, whereas the catalyst-coated substrate (CCS) demonstrated enhanced capabilities when the anode electrolyte was 1 M KHCO3. Further experiments also revealed that due to the distinct distribution of cathode electrolyte, CCS exhibited superior gas diffusion flux and stability, while CCM demonstrated higher catalyst utilization efficiency. These findings provide new insights into optimizing carbon dioxide reduction in zero-gap assemblies, and suggest that the anode electrolyte should be matched and optimized based on the different interface characteristics of the electrodes.