Mechanical Synthesis of COF Nanosheet Cluster and Its Mixed Matrix Membrane for Efficient CO₂ Removal

Covalent organic framework (COF) membranes used for selective removal of CO₂ were believed as an efficient and low-cost solution to energy and environmental sustainability. In this study, the amide modified COF nanosheet cluster with a 2D structure was facilely prepared through solid reaction, exhibiting good adsorption-based CO₂ selectivity (223 at 273 K and 90 at 298 K) toward N₂. Remarkably, the mixed matrix membrane (MMM) that consists of a lesser amount of COF filler (1 wt %) shows promising CO₂/N₂ gas selectivity (∼64). In addition, the competitive adsorption prompts the selectivity to ∼72 under an equimolar CO₂/N₂ mixture, which surpasses the values of all reported COF membranes. It is worth to note that the binary gas separation is stable during 120 h.