(114a) Redox-Tunable Lewis Bases for Electrochemical Carbon Dioxide Separation

Carbon capture is considered as a critical means for climate change mitigation. Conventional amine scrubbing utilizing sp³ amines suffers from high energy consumption, corrosion, and sorbent degradation, motivating the search for more efficient carbon dioxide separation strategies. Herein, we demonstrate a library of redox-tunable Lewis bases with sp²-nitrogen centers that can reversibly capture and release carbon dioxide through an electrochemical cycle. The mechanisms of the carbon capture process are elucidated via a combined experimental and computational approach. We show the properties of these Lewis base sorbents can be fine-tuned via rational molecular design and electrolyte engineering. Moreover, we identify a bifunctional azopyridine base that holds great promise for electrochemically-mediated carbon capture, which exhibits high efficiency, selectivity, and stability in a prototypical continuous flow separation system. The work broadens the structural scope of redox-active carbon dioxide sorbents and provides design guidelines on molecules with tunable basicity under electrochemical condition.