Kilowatt-scale alkali-cation-free CO2 electrolysis via accelerating mass transfer

Electrocatalytic CO₂ reduction (ECO₂R) presents a sustainable pathway for industrial decarbonization by converting CO₂ into carbon-neutral fuels and chemicals. Despite progress in catalyst design, industrial scalability is hindered by slow mass-transfer kinetics. Here, we introduce a high-diffusion-flux gas diffusion electrode (HDF-GDE) that overcomes this limitation in alkali-cation-free systems, achieving CO₂ conversion rates at industrial current densities. Kinetic analysis demonstrates that conversion is governed by mass transfer efficiency rather than flow rate. By optimizing the GDE structure to maximize CO₂ diffusion and GDE utilization, we realize a kW-scale ECO₂R system with stability (>1000 hours), producing CO or C₂H₄ depending on the catalyst. Operating with a 3 L/min CO₂ flow rate, the system delivers 144 kg of CO (1.29 kW) or 17 kg of C2H4 (1.95 kW) over 1000 h. The alkali-cation-free ECO2R system, equipped with HDF-GDEs, demonstrates economic viability for large-scale ECO2R-to-CO/C2H4 production. Our findings bridge the gap between lab innovation and real-world deployment, advancing carbon-neutral chemical manufacturing. Here the authors report a kilowatt-scale, alkali-cation-free CO₂ electrolysis system using high-diffusion-flux gas diffusion electrodes, achieving over 1000 h of stability for efficient CO or C₂H₂ production at industrially relevant current densities.