Ionomer-Driven Reaction Microenvironment Control in Bicarbonate-Mediated Integrated CO₂ Capture and Electrolysis

Bicarbonate electrolysis coupling upstream CO₂ capture with electrochemical conversion of captured CO₂ presents an energy-efficient alternative to existing CO₂ electrolysis route. Yet, its practical application is impeded by unsatisfactory reaction rate and energy efficiency. Here, we have improved the bicarbonate electrolysis performance through manipulating reaction microenvironments by introducing ionomers into cobalt phthalocyanine (CoPc) electrodes. The Nafion-incorporated CoPc electrode exhibits a maximum CO partial current density of 410 mA cm^-2 at a low cell voltage of 3.09 V in a cation exchange membrane-based zero-gap electrolyzer. Electrode structure characterization and finite element simulation results indicate that the proton conductivity of the Nafion ionomer increases the local concentration of in situ generated CO₂ around CoPc catalyst, resulting in impressive CO production performance. A closed-loop demonstration using the Nafion-incorporated CoPc electrode and a simulated flue gas underscores the great promise of the bicarbonate-mediated integrated CO₂ capture and electrolysis process.