Integrated capture and solar-driven utilization of CO2 from flue gas and air

Abstract

Integration of carbon capture with utilization technologies can lead the way to a future net-zero carbon economy. Nevertheless, direct conversion of chemically captured CO2 remains challenging due to its thermodynamic stability. Here, we demonstrate CO2 capture from flue gas or air and its direct conversion into syngas using solar irradiation without any externally applied voltage. The system captures CO2 with an amine/hydroxide solution and photoelectrochemically converts it into syngas (CO:H2 1:2 [captured from concentrated CO2], 1:4 [from simulated flue gas], and 1:30 [from air]) using a perovskite-based photocathode containing an immobilized molecular Co-phthalocyanine catalyst. At the anode, plastic-derived ethylene glycol is oxidized into glycolic acid over a Cu26Pd74 alloy catalyst. The overall process uses flue gas or air as carbon source, discarded plastic waste as an electron donor, and sunlight as the sole energy input. This strategy opens new avenues for future carbon-neutral or even negative solar fuel and waste upcycling technologies.