Improving the Sustainability of Electrochemical Direct Air Capture in a 3D Printed Redox Flow Cell

To enable the scale-up of electrochemical direct air capture (DAC), it is critical to enhance the sustainability of the process by maximizing efficiency and optimizing for targeted durability. Currently, many of the organic molecules reportedly used for electrochemical CO2 capture suffer from degradation upon extended redox cycling in the presence of oxygen, which generates chemical waste. Furthermore, off-the-shelf electrochemical flow cells-an integral piece of equipment for redox flow processes-cost thousands of dollars to procure. In this work, we addressed these challenges by exploring the DAC cyclability of five organic molecules. The highest performing molecule was phenazine, which maintained an average Coulombic efficiency of 100% over 9.5 h of testing with a theoretical minimum energy of 77.2 kJ/mol of CO2 captured. Additionally, we report the design and development of an economical 3D printed redox flow cell and its demonstration for electrochemical DAC.