Fibrous Metal-Organic Framework Membranes with Hierarchical Porous Channels for Efficient Carbon Dioxide Capture

The structural diversity and facile functionalization of metal-organic frameworks (MOFs) render them promising candidates for carbon dioxide (CO₂) adsorption and separation. However, the powdery characteristics cause poor mechanical stability and insufficient gas mass transfer, restricting their further applications. Herein, we report a promising strategy of in situ assembling ZIF-8 on the inner and outer surfaces of nanofibers to develop the fibrous ZIF-8 membranes with hierarchical porous channels. Particularly, the developed meso/macropores of the fibrous ZIF-8 membranes could facilitate the transport of CO₂ into ZIF-8, and the micropores of ZIF-8 offered massive active CO₂ adsorption sites. As a benefit from the unique design, the resulting fibrous ZIF-8 membranes had some fascinating features, including a high specific surface area of 273.29 m²/g and a high mechanical stress of 13.56 MPa. Moreover, the fibrous ZIF-8 membranes demonstrated a high CO₂ adsorption capacity of 3.14 mmol/g at 298 K and 1 bar and an excellent CO₂/N₂ selectivity of 35. After multiple cycles, the PAN/PVP/ZIF-8 membranes maintained 96.28% of their original CO₂ adsorption capacity. Furthermore, molecular dynamics simulations verify the robust binding interactions of the fibrous ZIF-8 membranes with CO₂ molecules. The integrated hierarchical porous channels proposed in this study provide a promising direction for designing fibrous MOF membranes for highly efficient CO₂ adsorption from flue gas.