High Efficiency Mixed Amine Adsorbents for Directly Capturing Carbon Dioxide from Air

The development of effective adsorbents with high amine efficiency and CO₂ adsorption almost unaffected by humidity is extremely challenging. In this study, we introduce an innovative solid amine adsorbent, TETA/DEA@FS, composed of triethylenetetramine (TETA) and diethanolamine (DEA) functionalized fumed silica (FS), which exhibits exceptional capability in selectively capturing trace CO₂ from N₂. TETA/DEA@FS shows an exceptionally high capacity of CO₂ adsorption of 1.13 mmol/g at the temperature of 298 K and the pressure of 0.0004 bar (1 bar=100 kPa), and achieves an unprecedented CO₂/N₂ IAST selectivity of 1.70×10¹². TETA/DEA@FS exhibits high amine efficiency, with breakthrough experiments demonstrating that CO₂ adsorption remains nearly unaffected by humidity. Meanwhile, TETA/DEA@FS demonstrates rapid CO₂ adsorption kinetics and outstanding cyclic stability.