Sustainable fabrication of highly (110)-oriented ZIF-8 membrane via supercritical fluid processing

Abstract

Preferred orientation control represents a crucial step for performance enhancement of MOF membranes. Nevertheless, their sustainable preparation remains a significant challenge. In this work, we fabricated highly (110)-oriented ZIF-8 membranes through supercritical fluid (SCF)-assisted epitaxial growth of oriented seed layer. Benefiting from unique physicochemical properties and intrinsic chemical inertness of supercritical CO₂, preferential orientation originated from the seed layer could be well maintained during epitaxial SCF processing; moreover, both unreacted ligands and discharged CO₂ could be efficiently recovered, resulting in zero pollutant emission. Our ZIF-8 membrane exhibited ideal C₃H₆/C₃H₈ selectivity of 91.8. To the best of our knowledge, this represented the first report of the preparation of highly oriented ZIF-8 membrane with such high C₃H₆/C₃H₈ selectivity; more importantly, our study demonstrated that SCF processing represented an effective protocol for orientation modulation of MOF membranes towards superior separations.