Balancing CO2 Mass Transport and Salt Precipitation via Multiparameter Optimization for Efficient Syngas Production in MEA Electrolyzers

Electrochemical CO2 reduction (eCO2RR) offers a sustainable route for converting CO2 into value-added chemicals and fuels, yet its practical application is hindered by CO2 transport limitations and salt precipitation in membrane electrode assembly (MEA) electrolyzers. In this work, we systematically investigated the effects of catalyst loading, gas diffusion layer (GDL) wettability, CO2 flow rate, CO2 temperature, and acid-vapor humidification on the eCO2RR performance. By systematically balancing electrode kinetics, CO2 mass transport, and salt precipitation, an optimal combination of operating conditions for the MEA-based eCO2RR is identified: catalyst loading of 1.0 mg cm–2, GDL water contact angle of 154°, CO2 flow rate of 100 sccm, inlet temperature of 50 °C, and CO2 humidification with 0.1 M HCl solution. Under these optimized parameters, the constructed MEA electrolyzer achieves the best eCO2RR performance, operating continuously for 20 h at a cell voltage of ∼2.27 V with an average Faradaic efficiency for CO of 92.7%. This study provides a practical framework for designing high-performance MEA systems with enhanced salt tolerance and long-term stability for syngas production.