Cooperative defect tailoring: A promising protocol for exceeding performance limits of state-of-the-art MOF membranes

Preferred orientation control represents an effective method for grain boundary defect elimination at the mesoscopic scale and therefore, performance enhancement of MOF membrane. In contrast, tailoring the separation performance of MOF membrane via structural defect engineering at the microscopic scale remains elusive. In this work, we pioneered the fabrication of (111)-oriented UiO-66 membrane via oriented tertiary growth. The use of ZrS2 as metal source during solvothermal synthesis led to higher number of missing linkers within the framework and therefore, preferential adsorption of CO2 over N2. In comparison with secondary growth, both CO2/N2 selectivity and CO2 permeability of obtained UiO-66 membrane after tertiary growth were concurrently increased, thereby transcending both the 2008 Robeson upper bound and the separation performance limits of state-of-the-art polycrystalline MOF membranes for CO2/N2 gas pair.