Emerging porous framework material-based nanofluidic membranes toward ultimate ion separation

Summary

Ion sieving at the angstrom scale has become one of the research foci in fields such as nanofluidics and membrane separation over the last decade. Nanopores/channels have been constructed with various materials to achieve promising ion-ion selectivity. In recent years, porous framework materials (PFMs; including metal-organic frameworks and covalent-organic frameworks) with ordered nanochannels and tunable chemistries have been shown to exhibit ultrafast ion transport and ultrahigh ion selectivity, which represents an exciting development in mimicking the functions of biological ion channels. This perspective highlights desirable structures and properties of PFMs for ion separation, including sub-nanometer pore size, wettability, charge density, and framework functional groups. It also briefly reviews the advantages and progress of PFM-based nanofluidic membranes for ion separation and discusses the challenges in the development of such membranes for practical applications.