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

Abstract Hydrogen (H 2 ) 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. H 2 purification membranes need to exhibit both high H 2 permeance and sufficient H 2 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‐SO 3 H) gutter layer, and a zeolitic imidazolate framework‐8 (ZIF‐8) selective layer. The TpPa‐SO 3 H 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‐SO 3 H]‐[ZIF‐8]/PAN membrane achieves a hydrogen permeance of 1429.4 GPU and an H 2 /N 2 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.