Continuous conversion of flue gas into syngas by a bipolar membrane-integrated single-cell cyclic system

Abstract

Electrochemical CO₂ reduction reaction (ECO₂RR) usually requires high-purity CO₂ gas feeding. However, capturing CO₂ from flue gas is still a cost- and energy-intensive process. Here, we design a bipolar membrane-integrated single-cell cyclic system that directly converts simulated flue gas into syngas. The system features a circulating gas-liquid mixed flow between the anode and cathode in an integrated cell, enabling it to simultaneously absorb CO₂ from flue gas and convert captured CO₂ into syngas. At an industrial current density of 250 mA/cm², we successfully decrease the CO₂ concentration in flue gas from 15% to 4.3% (with a 61.7% CO₂ capture efficiency) and obtain high-selectivity (up to 100%) syngas (H₂:CO = 3:1). Moreover, this cell has excellent tolerance to SO_x and NO_x due to the Ni single-atom catalyst in the cathode compared with previous studies. These results pave the way for low-concentration carbon dioxide conversion and promote the application of ECO₂RR technology.