Constructing Self-Adaptive Pores in a Metal–Organic Framework for Capturing CO ₂ from Wet Flue Gas

Efficient capture of CO₂ from industrial flue gas is crucial for achieving carbon neutrality. However, this goal remains a huge challenge due to the fact that the polarity and size of CO₂ lie between those of H₂O and N₂. Here, we design and synthesize a novel metal-organic framework (MOF) (FJI-H46) featuring a flexible framework, ultramicropores matched with CO₂, and Cl⁻ sites capable of adaptively recognizing CO₂ from wet flue gas. FJI-H46 has excellent chemical stability and can maintain structural integrity even under strong acids, strong bases, and high temperatures. It can efficiently capture CO₂ from simulated flue gas with ultrahigh adsorption capacity, exceptionally high selectivity, and very low adsorption enthalpy. This outstanding performance stems from the synergistic effect among the adaptive movement of Cl⁻ sites, the adaptive deformations of the flexible framework, and the confinement effect of ultramicropores. Such synergy also results in a higher initial adsorption enthalpy of FJI-H46 for CO₂ than H₂O, and a much faster adsorption rate for CO₂ than H₂O, thereby effectively suppressing competitive adsorption of H₂O. Even at 100% relative humidity (RH), FJI-H46 demonstrates exceptional carbon capture capacity, remarkable ability to suppress H₂O coadsorption, and outstanding long-term tolerance to repeated H₂O adsorption and desorption.