Constructing Self-Adaptive Pores in a Metal-Organic Framework for Capturing CO2 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.