Rapid synthesis strategy of ultrathin UiO-66 separation membranes: Ultrasonic-assisted nucleation followed with microwave-assisted growth

The Metal-Organic Framework (MOF) materials are ideal molecular sieving membrane materials due to the regular pores with high-density and good designability, which have been widely studied in gas separation, desalination, and nanofiltration, etc. However, most preparation methods of MOF polycrystalline membranes are always time-consuming and the as-synthesized MOF membranes are thick. Here in this work, the ultrathin 210 nm-UiO-66 polycrystalline membranes are rapidly synthesized in 1 h, where sonication is utilized to generate massive tiny nucleation followed with rapid microwave-assisted membrane growth. The Na+ rejection of the UiO-66 membrane maintains at 99.6% for 700 h long-term experiment with 0.16 L/(m2 h bar) of water flux in forward osmosis, indicating the good quality and excellent stability of the as-synthesized membrane. This strategy is also expected to synthesize many other continuous defect-free MOF membranes with ultrathin thickness rapidly.