Fabrication of highly c-oriented defect-rich MIL-125 membrane from nanosheets towards exceptional CO2/N2 separation

Although challenging, multi-scale structure tailoring has been proven to significantly enhance the separation performance of MOF membranes. In this study, through engineering seed morphology and innovating metal source, highly c-oriented MIL-125 membrane with tailored missing-linker defects was facilely prepared. Experimental results indicated that iron (III) acetylacetonate could serve as competent modulator for preparing uniform NH2-MIL-125(Ti/Fe) nanosheet seeds, while employing Ti6-oxo cluster source warranted precise tailoring of missing-linker defects in the framework. Through combining with single-mode microwave heating during secondary growth, we prepared highly c-oriented defect-rich MIL-125 membrane with CO2/N2 separation factor of 47.7 ± 1.8 and CO2 permeance of 720.6 ± 24.3 GPU, which remarkably surpassed the separation performance limit of state-of-the-art MOF membranes, demonstrating significant potential for energy-efficient CO2 capture from flue gas.