A new hybrid sorbent represents potential to significantly increase the cost-effectiveness of direct air capture (DAC) of carbon dioxide. The Lewis acid-base interaction–derived hybrid sorbent with polyamine-copper(II) complex formulated by researchers from Tianjin University, China, and Pennsylvania’s Lehigh University enables carbon dioxide (CO₂) capture of more than 5.0 mol/kg sorbent, nearly three times greater capacity than most of the DAC sorbents tested to date.

Unlike traditional sorbents, the copper-enriched material described in Science Advances does not need to be heated to 100° C to extract the CO₂ for storage, providing further energy savings. Mechanically strong and chemically stable, the hybrid sorbent is amenable to efficient regeneration by salt solutions at an ambient temperature, including seawater. In addition, the material is regenerable with waste heat or thermal energy at less than 90° C.

The desorbed CO₂ is simultaneously sequestered as innocuous baking soda. The alkaline nature of the sorbent could also potentially help reverse ocean acidification trends.

Laboratory trials confirmed that the polyamine-Cu(II) complex capacity for CO₂ capture with only 400 ppm or 0.04% inlet CO₂ was much greater than other sorbents capturing flue gases containing 11% CO₂. The researchers plan to launch a dedicated company to develop the technology further and test whether it could work at scale outside of the lab.