Flexible Polyacrylonitrile-Supported MOF-on-COF Composite Membrane for Hydrogen Purification

Hydrogen (H₂) is a clean and efficient energy source that has garnered global technological development to enhance its production. However, effective purification is necessary to remove impurities from hydrogen products. H₂ purification membranes need to exhibit both high H₂ permeance and sufficient H₂ selectivity. Herein, this study presents an in situ growth method to prepare a composite metal-organic framework (MOF)-on- covalent organic framework (COF) membrane for hydrogen purification, consisting of a polyacrylonitrile (PAN) substrate, a sulfonated triphenylphosphine acid (TpPa-SO₃H) gutter layer, and a zeolitic imidazolate framework-8 (ZIF-8) selective layer. The TpPa-SO₃H layer is prepared on the PAN substrate via an in situ growth method and used to anchor the metal precursors of ZIF-8 to form a continuous and dense ZIF-8 layer on its surface. The resulting [TpPa-SO₃H]-[ZIF-8]/PAN membrane achieves a hydrogen permeance of 1429.4 GPU and an H₂/N₂ selectivity of 22.9. These results highlight the potential of composite membranes in advancing hydrogen separation technology and provide a promising approach for efficient hydrogen purification.