Advanced Solid Amine Adsorbents with Exceptional Oxidative Stability for Efficient Capture of Low‐concentration CO2

Abstract Solid amine adsorbents designed for capturing trace amounts of carbon dioxide (CO 2 ) offer a promising approach. However, developing solid amine adsorbents that concurrently exhibit high oxidative stability and superior CO 2 adsorption capacity remains a significant challenge. Here, ED‐PEI/PEG@FS‐TBP, an innovative and highly stable CO 2 adsorbent is introduced. This material involves the functionalization of polyethyleneimine (PEI) with 1,2‐epoxydodecane (ED), effectively transforming primary amines into secondary amines, thereby mitigating urea formation. Furthermore, the chelator embedded within the fumed silica (FS) supports sequestering metallic impurities that would otherwise catalyze oxidation reactions. The integration of polyethylene glycol (PEG) forms hydrogen bonds with PEI, effectively barricading oxygen access and safeguarding against PEI oxidation. ED‐PEI/PEG@FS‐TBP achieves an outstanding CO 2 adsorption capacity of 1.49 mmol g −1 at 298 K and 0.0004 bar. Notably, after 20 days of oxidative aging in an environment with 75% relative humidity and 383 K, ED‐PEI/PEG@FS‐TBP exhibits remarkable oxidative stability, with a deactivation rate constant ( k deact ) 93% lower than that of PEI@FS. Its excellent oxidative stability, cycling stability, and high thermal stability, underscore its unparalleled potential for the capture of low‐concentration CO 2 .