Electrochemically Mediated Direct CO Capture by a Stackable Bipolar Cell.

The unprecedented increase in atmospheric CO concentration calls for effective carbon capture technologies. With distributed sources contributing to about half of the overall emission, CO capture from the atmosphere [direct air capture, (DAC)] is more relevant than ever. Herein, an electrochemically mediated DAC system is reported which utilizes affinity of redox-active quinone moieties towards CO molecules, and unlike incumbent chemisorption technologies which require temperature or pH swing, relies solely on the electrochemical voltage for CO capture and release. The design and operation of a DAC system is demonstrated with stackable bipolar cells using quinone chemistry. Specifically, poly(vinylanthraquinone) (PVAQ) negative electrode undergoes a two-electron reduction reaction and reversibly complexes with CO , leading to CO sequestration from the feed stream. The subsequent PVAQ oxidation, conversely, results in release of CO . The performance of both small- and meso-scale cells for DAC are evaluated with feed CO concentrations as low as 400 ppm (0.04 %), and energy consumption is demonstrated as low as 113 kJ per mole of CO captured. Notably, the bipolar cell construct is modular and expandable, equally suitable for small and large plants. Moving forward, this work presents a viable and highly customizable electrochemical method for DAC.