Synergistic bulk-interface engineering of polymodal micro-mesoporous carbon molecular sieve membranes for high-performance hydrogen separation

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: Energy-efficient gas separations necessitate the development of high-performance membrane materials. Carbon molecular sieve (CMS) membranes are regarded as highly promising candidates; however, it remains a challenge to precisely control the pore size and distribution of the membranes in order to achieve efficient molecular-level separations. Here, we report a distinct series of polymodal micro-mesoporous CMS membranes with excellent gas separation performance, which are engineered via a bulk-interface co-regulation strategy based on the incorporation of silane-functionalized iron oxide (Silane@Fe 3 O 4 ) nanoparticles and in situ pyrolysis. The Fe 3 O 4 nanoparticles grafted with organosilicon compounds exhibit good dispersibility and interfacial compatibility within the polymer matrix, enabling the synergistic regulation of the bulk-interface microstructure of derived hybrid CMS membranes during pyrolysis. By optimizing the fabrication conditions, such as filler loading level and pyrolysis temperature, a polymodal pore network, composed of concentrated mesopores (3-4 nm) and tight ultramicropores (< 0.7 nm), is well-constructed, providing a shortened transport pathway and enhanced molecular-sieving capability. The resulting hybrid CMS membrane not only demonstrates high H 2 permeability of 7773 Barrer, but also exhibits attractive long-term separation performance with H 2 /N 2 selectivity of 241.4 during a continuous 720 h binary mixture feeding, which lies far above the latest upper bounds. This work provides a novel and simple strategy to synergistically regulate the polymodal porous structure of CMS membranes for efficient gas separation.