In-situ interfacial assembly of ultra-H2-permeable metal-organic framework membranes for H2/CO2 separation

H2/CO2 splitting is one of the most urgently demanded but challenging technologies in industry. Ultra-H2-permeable metal-organic framework (MOF) membranes with high selectivity show great promise for energy-efficient separations, but a huge obstacle is the deficiency of facile and reliable fabrications to control the orientation and thickness of membranes that determines mass-transfer characteristics. We demonstrate the fabrication of layered Zn2(bim)4 membranes by means of an in-situ interfacial assembly (ISIA) approach involving the impregnation of limited zinc ions into the pores of a support under controlled negative pressure and the tuning of metal-linker reactions at the interface to achieve the well-matched nucleation and epitaxy growth. The ultrathin c-oriented membranes with disordered layer-by-layer stacking microstructure in crystallography achieve H2 permeances of 6300-10680 GPU and H2 selectivity toward CO2 of up to 86.5, far exceeding the Robeson’s upperbound for H2/CO2 separation.