Amine-mediated, oxygen-tolerant concerted capture and electrochemical conversion of CO2 from flue gas

Integrated capture and electrochemical conversion of CO2 from flue gas can mitigate the energy penalties of conventional decoupled processes, offering a promising pathway to reduce CO2 emissions and valorize carbon resources. However, this strategy has not yet been fully realized because of the mismatch between the rates of CO2 capture and electrolysis. Herein, we report a concerted system integrating CO2 capture and electrochemical conversion from flue gas using monoethanolamine (MEA) as the mediator. MEA captures CO2 from flue gas and delivers it in liquid form to an electrolyzer, where the captured CO2 is electrochemically converted into CO with concurrent MEA regeneration. The regenerated MEA is recycled to the absorber for another round of CO2 capture, establishing a sustainable closed loop for simultaneous CO2 capture and electrolysis. Owing to the low solubility of O2 in the MEA solution, the system exhibits strong oxygen tolerance, avoiding efficiency loss caused by the competing oxygen reduction reaction. By examining key parameters such as current density, electrode hydrophobicity, and CO2 concentration, the concerted system achieves a high CO2 capture efficiency of 63% for flue gas containing 15% CO2 and produces a syngas with an H2/CO = 3.2 over 24 h of operation. This work demonstrates the first MEA-based system for concerted capture and conversion of CO2 from flue gas, offering an effective strategy for sustainable carbon recycling and syngas production.