Covalent organic framework nanosheets (CONs) are a class of two-dimensional layered materials with exceptional properties. The inherent features of COF materials

such as pre-designable periodic structures

atomic-level precision

tunable functionality

excellent thermal stability

permanent porosity

and ultralow density

endow CONs with significant potential for further development. However

challenges such as low exfoliation efficiency of COF nanosheets and poor size controllability complicate membrane fabrication processes. In this study

a liquid-phase exfoliation method was employed to prepare pyridine-based COF nanosheets (TpBpy-CON) and assemble them into COF membranes (TpBpy-COM). COF powders were exfoliated under mild conditions to obtain size-controllable TpBpy-CON. The resulting COF nanosheets exhibited high aspect ratios

specific surface areas

and porosity. Subsequently

the nanosheets were assembled into COF membranes using vacuum-assisted techniques. The fabricated TpBpy-COM demonstrated a compact membrane surface structure and excellent H2/CO2 gas separation performance.