Zwitterionic carbamate interfaces unlock efficient “liquid” CO 2 upgrading

Integrating carbon dioxide (CO 2 ) capture with its direct electrochemical conversion remains a major challenge for sustainable energy technologies. Although amine scrubbing is widely used for CO 2 capture, its integration with electrochemical reduction is often inefficient due to poor mass transport and limited reactivity of captured CO 2 species. Here, we report an integrated capture-conversion platform that enables direct electrolysis of amine-captured CO 2 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 CO 2 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 cm 2 ), rapid CO 2 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.