Integrated Capture and Conversion of Dilute CO ₂ Using an Oxygen Tolerant Porous Carbon Modified Gas Diffusion Electrode

Integrated capture and conversion of low-concentration CO 2 is a critical step toward carbon neutrality. Here, we demonstrate a gas diffusion electrode (GDE) modified with oxygen- and nitrogen-functionalized porous graphitic carbon (ONC) that enables efficient electroreduction of dilute CO 2 . Under 15% CO 2 gas (without O 2 ), the ONC-modified GDE achieved a CO 2 -to-formic acid conversion rate of 250 μmol/h·cm 2, 2.5 times higher than that of the bare GDE, with a Faradaic efficiency (FE) of 98%. Even in flue gas containing 8% O 2, the modified GDE achieved 22 μmol/h·cm 2 formic acid production (8% FE) at −1.4 V RHE . Mechanistic and simulation studies revealed that the oxygen functional groups in ONC enhance CO 2 adsorption while suppressing O 2 permeation, imparting strong oxygen tolerance. In particular, the ONC-modified GDE remains active at a CO 2 concentration as low as 1% and 400 ppm, suggesting potential applicability in integrated capture–conversion systems that utilize dilute CO 2 streams from flue gas and ambient air.