Carbon dioxide capture from open air using covalent organic frameworks

Capture of CO₂ from the air offers a promising approach to addressing climate change and achieving carbon neutrality goals^1,2. However, the development of a durable material with high capacity, fast kinetics and low regeneration temperature for CO₂ capture, especially from the intricate and dynamic atmosphere, is still lacking. Here a porous, crystalline covalent organic framework (COF) with olefin linkages has been synthesized, structurally characterized and post-synthetically modified by the covalent attachment of amine initiators for producing polyamines within the pores. This COF (termed COF-999) can capture CO₂ from open air. COF-999 has a capacity of 0.96 mmol g^-1 under dry conditions and 2.05 mmol g^-1 under 50% relative humidity, both from 400 ppm CO₂. This COF was tested for more than 100 adsorption-desorption cycles in the open air of Berkeley, California, and found to fully retain its performance. COF-999 is an exceptional material for the capture of CO₂ from open air as evidenced by its cycling stability, facile uptake of CO₂ (reaches half capacity in 18.8 min) and low regeneration temperature (60 °C).