Spray‐coating of lamellar MOF/ionic liquid membranes for high‐performance <scp> H ₂ </scp> purification

Abstract Hydrogen purification is essential for the transition to a clean energy economy, yet the practical application of membrane technology remains limited by the challenge of achieving high gas separation performance under industrial conditions. Herein, we report a facile layer‐by‐layer spray‐coating approach to fabricate sandwich‐structured membranes comprising CuBDC metal–organic framework (MOF) nanosheets serving as outer layers and ionic liquid (IL, [BMIM][BF 4 ]) as the inner layer. The IL is electrostatically confined within the CuBDC interlayers, effectively sealing non‐selective defects while creating strong CO 2 ‐philic domains that retard CO 2 permeation. The optimized membrane delivers a moderate H 2 permeance over 1904 GPU and an H 2 /CO 2 selectivity of 12.6, surpassing the 2008 Robeson upper bound. Furthermore, process simulation of a two‐stage membrane system demonstrates the potential to achieve &gt;98% hydrogen purity with a recovery of 95.39%. With excellent stability over 100 h, this work establishes a scalable and energy‐efficient pathway for industrial hydrogen purification.