Synergistic Ag@ SiO 2 enables ultrapermeable carbon molecular sieving membranes for O 2 / N 2 separation

Abstract Carbon molecular sieving membranes (CMSMs) were fabricated from polyimide precursor incorporated with Ag@SiO 2 via membrane‐casting and pyrolysis. The well‐dispersed particles enhance precursor thermal stability and promote gas permeation pathways in the resulting CMSMs. With increasing Ag@SiO 2 loading, the permeabilities of H 2 and CO 2 generally increase, albeit with slightly reduced H 2 /N 2 and CO 2 /N 2 selectivities. Ag@SiO 2 significantly improves O 2 permeation and selectivity through Ag‐facilitated adsorption and SiO 2 ‐mediated microstructural modulation, as confirmed by gas adsorption capacity. Higher temperatures and lower pressures benefit gas transport. The optimal CMSM with 0.5 wt% Ag@SiO 2 yields an O 2 permeability of 1605.6 Barrer and an O 2 /N 2 selectivity of 8.1. These values surpass the 2015 Robeson upper bound, highlighting the synergy between specific adsorption and pore engineering. This work offers a competitive strategy for O 2 /N 2 membrane technology toward efficient air separation.