Redox-tunable Lewis bases for electrochemical carbon dioxide capture

Carbon capture is considered a critical means for climate change mitigation. However, conventional wet chemical scrubbing utilizing sp 3 amines suffers from high energy consumption, corrosion and sorbent degradation, motivating the search for more efficient carbon dioxide separation strategies. Here, we demonstrate a library of redox-tunable Lewis bases with sp 2 -nitrogen centres that can reversibly capture and release carbon dioxide through an electrochemical cycle. The mechanism of the carbon capture process is elucidated via a combined experimental and computational approach. We show that the properties of these Lewis base sorbents can be fine-tuned via molecular design and electrolyte engineering. Moreover, we identify a bifunctional azopyridine base that holds promise for electrochemically mediated carbon capture, exhibiting >85% capacity utilization efficiency over cycling in a flow system under 15% carbon dioxide with 5% oxygen. This work broadens the structural scope of redox-active carbon dioxide sorbents and provides design guidelines on molecules with tunable basicity under electrochemical conditions. Electrochemical approaches to carbon capture have the advantages of operation under ambient conditions and modular design, but improved sorbent molecules are still needed. Here the authors present a library of redox-tunable Lewis bases, shedding light on molecular design guidelines to tune sorbent properties.