Zwitterionic carbamate interfaces unlock efficient "liquid" CO₂ upgrading

Integrating carbon dioxide (CO₂) capture with its direct electrochemical conversion remains a major challenge for sustainable energy technologies. Although amine scrubbing is widely used for CO₂ capture, its integration with electrochemical reduction is often inefficient due to poor mass transport and limited reactivity of captured CO₂ species. Here, we report an integrated capture-conversion platform that enables direct electrolysis of amine-captured CO₂ in liquid carbamate solutions. Screening structurally related amines identifies piperazine (PZ) as an effective capture agent that forms stable, highly concentrated carbamate species. When combined with a nickel-based catalyst and a designed gas-liquid-solid interface, the system enables efficient liquid-phase CO₂ conversion, achieving up to 60% Faradaic efficiency for carbon monoxide (CO) and providing the first quantitative verification of carbamate participation (~40%). In a scaled electrolyzer (9 cm²), rapid CO₂ capture and release kinetics enable CO Faradaic efficiencies of 30 to 45% and energy efficiencies of ~15 to 25% under ambient conditions, with stable operation over 150 hours.