Hydrogen-bonded organic framework membranes through dispersion-controlled deposition method for efficient CO2 separation

Abstract

Hydrogen-bonded organic frameworks (HOFs) feature a highly ordered pore structure, abundant organic functional groups, and unique solution-processability, holding great promise in gas separations. In this study, we explored the fabrication of HOF membranes utilizing a dispersion-controlled deposition (DCD) method. To achieve homogeneous dispersion, the bulk HOF aggregates were initially dispersed in solvent and then switched to anti-solvent to generate the precipitated nanoparticles. Under vacuum-assisted assembly, the HOF colloidal solution containing nanoparticles was uniformly deposited, and the intracrystalline defects were spontaneously healed during the mixed-solvent evaporation. For the first time, HOF polycrystalline membranes were fabricated on flexible polymer substrates and demonstrated an ultrathin HOF selective layer of ~100 nm. The prepared HOF membranes exhibited high separation performance, with the CO₂ permeance exceeding 600 GPU and the CO₂/N₂ selectivity exceeding 30. This work establishes a platform technology for HOF membrane fabrication and expands the families of carbon capture membranes.