Electrochemically Mediated Direct CO₂ Capture by a Stackable Bipolar Cell

Abstract

The unprecedented increase in atmospheric CO₂ concentration calls for effective carbon capture technologies. With distributed sources contributing to about half of the overall emission, CO₂ 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 CO₂ molecules, and unlike incumbent chemisorption technologies which require temperature or pH swing, relies solely on the electrochemical voltage for CO₂ 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 CO₂ , leading to CO₂ sequestration from the feed stream. The subsequent PVAQ oxidation, conversely, results in release of CO₂ . The performance of both small- and meso-scale cells for DAC are evaluated with feed CO₂ concentrations as low as 400 ppm (0.04 %), and energy consumption is demonstrated as low as 113 kJ per mole of CO₂ 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.