ZIF-8 penetrating composite membrane for ion sieving

Ion sieving is essential for biological systems and membrane-based applications. At present, metal-organic framework (MOF) membranes are of great interest for use in ion separation, but it remains a great challenge to design high quality MOF membranes with a simple preparation process and desirable ion selectivity. Herein we fabricate a MOF composite membrane, containing highly penetrated ZIF-8 channels. The ZIF-8 channels are the dominant pathways for ion transport and display a good Li+/Mg2+ sieving performance (Li+/Mg2+ ​= ​6.1). The simulation reveals that the Li+/Mg2+ selectivity is associated with the significant disparity of transport energy barrier between them, which is caused by the different extent of ion dehydration in angstrom-scale ZIF-8 channels. This work provides an effective strategy to develop ionic sieving membranes based on penetrating MOF channels for lithium extraction.