Amine-functionalized covalent organic frameworks for high-performance carbon dioxide capture.

Covalent organic frameworks (COFs) have garnered significant interest as advanced platforms for carbon capture, utilization, and storage, owing to their high surface area, tunable porosity, and excellent chemical stability. However, their practical deployment for carbon dioxide (CO) capture, particularly under the low-concentration conditions characteristic of industrial flue gas, remains a major challenge. Herein, an amine-functionalized COF, designated TaTp-COF, is synthesized via spontaneous enol-to-ketoamine tautomerization, introducing a high density of uniformly distributed secondary amine groups that enhance CO binding affinity. TaTp-COF delivers an impressive CO uptake of 5.0 mmol g at 0 °C and 1 bar, alongside outstanding thermal stability and cycling durability. Importantly, it maintains high adsorption efficiency at low CO partial pressures, demonstrating strong potential for flue gas treatment. The material also achieves exceptional CO/N selectivity (233, V:V = 15:85), surpassing most reported porous adsorbents. Spectroscopic analyses, complemented by theoretical calculations, confirm the formation of carbamic acid species upon CO adsorption, indicative of strong host-guest interactions and efficient amine site utilization. The uniform dispersion of active centers contributes to enhanced binding strength, suppressed desorption at elevated temperatures, and reduced secondary emissions. This work positions TaTp-COF as a promising next-generation adsorbent for scalable and energy-efficient CO capture and flue gas purification, while offering valuable design insights for functionalized COFs in sustainable gas separation technologies.