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.