Construction of Metal-Organic Frameworks (MOFs)-Based Membranes and Their Ion Transport Applications.

Biological ion channels with delicate ion transport functions exist widely in living organisms. Bioinspired solid-state channels have emerged as promising platforms to mimic the working mechanism of natural channels. These channels help in understanding the mechanism of ion transport in biosystems and pave the way for applications in several interesting areas. Metal-organic frameworks (MOFs), constructed by connecting metal ions and organic ligands, exhibit high porosity and unique pore structures. They also possess tunable pore sizes and are versatile in their compositions. And there are rich molecule/ion-specific functional groups in the frameworks, which can intelligently modulate ion transport. Thus, MOFs are promising candidates that mimic biological ion channels. Herein, the recent progress in the design and construction of artificial solid-state MOF-based channels is focused on. The excellent ion transport properties of MOF-based membranes are also summarized, including ionic selectivity, ionic rectification, and ionic gating. Following this, four emerging ion transport applications, namely, energy conversion, ion/molecule separation, biosensing, and water desalination, are highlighted. Finally, an outlook on future developments and challenges in this exciting research area is presented.