TEOS-assisted in situ growth of NH₂-ZIF-8 membranes for hydrogen separation

The fabrication of ultrathin and defect-free metal-organic framework （MOF） membranes remains a significant challenge in gas separation applications. A molecular anchoring strategy based on the hydrolysis of tetraethyl orthosilicate （TEOS） is employed for the first time to enhance interfacial nucleation and membrane densification of NH₂-ZIF-8 on polyvinylidene fluoride （PVDF） substrates. Silanol groups generated during TEOS hydrolysis act as effective molecular anchoring sites, preferentially adsorbing Zn²⁺ ions and enriching metal precursors at the interface, thereby directing the dense in situ growth of NH₂-ZIF-8 crystals and promoting the formation of a continuous membrane layer. The effects of TEOS content on membrane structure and gas separation performance were systematically investigated. Experimental results demonstrate that the NH₂-ZIF-8 membrane prepared with 0.8 ml TEOS exhibits optimal separation performance, achieving a hydrogen permeability of 409.6 GPU and an H₂/CO₂ ideal selectivity of 20.7. This work provides a simple and efficient interfacial engineering approach for constructing high-performance MOF separation membranes on polymer substrates.