Room-temperature synthesis of defect-engineered Zirconium-MOF membrane enabling superior CO2/N2 selectivity with zirconium-oxo cluster source

Room-temperature (RT) synthesis of high-performance MOF membranes is particularly attractive for their batch production in industry. Nevertheless, to date there remains no report on RT preparation of high-valent transition metal-oxo node-based MOF (like UiO-66) membranes since in general higher activation energy is required for the formation of metal-oxo nodes prior to the membrane growth. In this work, we pioneered the preparation of well-intergrown UiO-66 membranes at RT, which could be realized by direct using Zr6O4(OH)4-oxo cluster as zirconium source. Moreover, UiO-66 synthesized at RT exhibited higher defect densities, which was advantageous for enhancing the CO2/N2 selectivity via attractive interaction between CO2 and defective sites. Defect-engineered UiO-66 membrane fabricated through tertiary growth at RT exhibited exceptional CO2/N2 selectivity of 37.8, which was the highest value among all pristine polycrystalline MOF membranes tested under similar conditions. Our results convincingly demonstrate that using metal-oxo cluster source represents a promising protocol for facile and mild high-performance MOF membrane preparations.