Lamellar ZIF-8 nanosheets empowered thin-film nanocomposite membrane with synergistic sieving and rapid water transport for enhanced desalination

The development of reverse osmosis membranes that simultaneously achieve high water permeability and excellent salt rejection is an urgent yet challenging goal for sustainable desalination. Two-dimensional (2D) nanofillers offer a promising pathway to break the inherent trade-off by creating fast water-transport channels. Herein, we engineered a high-performance thin-film nanocomposite (TFN) membrane by incorporating lamellar zeolitic imidazolate framework-8 nanosheets (ZIF-8 NSs) into the polyamide selective layer. The ZIF-8 NSs, synthesized via a facile surfactant-directed approach, possess an ultrathin thickness of ∼5.5 nm and a large lateral size of ∼0.75 μm. When embedded at an optimal loading, the TFN membrane demonstrates a remarkable water permeability of 9.83 L m −2  h −1 MPa −1 , which is ∼37% higher than the pristine thin-film composite (TFC) membrane, while maintaining a high Na 2 SO 4 rejection of 97.9%. This superior performance, significantly surpassing that of membranes filled with conventional ZIF-8 nanoparticles, is attributed to the synergistic effect of the molecular-sieving function of intrinsic ZIF-8 pores and the low-resistance nanochannels formed by the interlayer galleries between the well-dispersed nanosheets, which concurrently facilitate a more cross-linked polyamide network. This work provides a viable and scalable strategy for using 2D MOF nanosheets to design advanced separation membranes.