Metal Ion‐Induced Reconfiguration of Membrane Microstructure and Gas Affinity for Enhanced H₂/CO₂ Separation

Polymer membranes fabricated via interfacial polymerization (IP) hold significant commercial promise for hydrogen purification from syngas—enabling clean H 2 energy harvesting while capturing CO 2 , a major greenhouse gas. However, achieving simultaneous enhancement of H 2 permeance and H 2 /CO 2 selectivity remains a major challenge due to the inherently broad pore size distribution of polymer membranes. Herein, a metal ion‐induced monomer assembly strategy is proposed to concurrently regulate micropore structure and gas adsorption characteristics during the IP process. The presence of metal ions guided the formation of an “hourglass‐shaped” microporous architecture with increased porosity and a narrowed pore size distribution. Furthermore, the incorporated metal ions enhanced CO 2 adsorption, selectively hindering CO 2 transport while allowing H 2 permeation. Benefiting from the synergistic effects of structural tuning and selective adsorption, the resulting membrane exhibited both high H 2 permeance (412.5 GPU) and H 2 /CO 2 selectivity (20.3) in a 50:50 mixed‐gas system, surpassing Robeson's upper bound. For practical demonstration, the optimized membrane is employed in a two‐stage separation configuration, achieving high‐purity H 2 (99.5%) with a significantly reduced energy consumption of 2.45 MJ kg −1 , underscoring its strong potential for industrial application.