Interface-engineered ZIF-8/PPSU bilayer composite membranes for advanced hydrogen separation

This study proposes an interface-engineered strategy for constructing robust ZIF-8/PPSU double-layer membranes, aiming to achieve high-performance hydrogen separation. A customized seed implantation technique was employed to ensure precise anchoring of ZIF-8 seeds within the micro/nano-structured surface layer of a polyphenylsulfone (PPSU) base membrane. This strategy enabled the subsequent epitaxial growth of a continuous, defect-free ZIF-8 separation layer on an alumina-supported PPSU substrate. The method effectively engineered the organic-inorganic interface, converting weak physical contacts into a tightly integrated heterostructure. The resulting ZIF-8/PPSU membranes exhibited outstanding hydrogen sieving performance, significantly surpassing that of the pure PPSU counterpart. Under optimal conditions, the membrane demonstrated a hydrogen permeability of 16,211.03 barrer, with selectivities of 7.06 for H 2 /CO 2 , 23.15 for H 2 /N 2 , and 28.91 for H 2 /CH 4 , thereby exceeding the Robeson upper bound. The enhanced interfacial adhesion can be attributed to a synergistic combination of factors. The seeded micro-topography provides a mechanical interlocking effect. Van der Waals forces and hydrogen-bond interactions are present between PPSU polar groups (sulfone/ether) and ZIF-8 nodes/linkers. Seamless epitaxial continuity is maintained during secondary growth. This work demonstrates that rational interface engineering via seed implantation is an effective route to eliminate non-selective voids and achieve superior gas separation efficiency in MOF/polymer composite membranes.