Electrochemical direct air capture of CO₂ using neutral red as reversible redox-active material

Direct air capture of carbon dioxide is a viable option for the mitigation of CO₂ emissions and their impact on global climate change. Conventional processes for carbon capture from ambient air require 230 to 800 kJ thermal per mole of CO₂, which accounts for most of the total cost of capture. Here, we demonstrate electrochemical direct air capture using neutral red as a redox-active material in an aqueous solution enabled by the inclusion of nicotinamide as a hydrotropic solubilizing agent. The electrochemical system demonstrates a high electron utilization of 0.71 in a continuous flow cell with an estimated minimum work of 35 kJ_e per mole of CO₂ from 15% CO₂. Further exploration using ambient air (410 ppm CO₂ in the presence of 20% oxygen) as a feed gas shows electron utilization of 0.38 in a continuous flow cell to provide an estimated minimum work of 65 kJ_e per mole of CO₂.