Polymer-based membranes for promoting osmotic energy conversion

Membrane-based reverse electrodialysis is a promising technology for harvesting the osmotic energy to solve the increasingly severe energy problems. However, the osmotic power generation generally suffers from low power output for the poor performance of the ion-exchange membranes. Recently, bioinspired nanochannel membranes are emerging as an appealing materials platform for high-performance osmotic energy conversion owing to their tailorable physiochemical properties. In this review, we discuss tailored ion transmembrane transport and highlight the tunable synthesis of various polymeric materials with nanochannels for osmotic energy conversion, involving homopolymer membrane, blend membrane and Janus membrane. We then present a discussion of the structure−property relationships of polymeric nanochannel membrane based on ion transport dynamics, ultimately targeting properties such as enhanced ionic conductivities, ion selectivity, ion rectification, and desirable mechanical strength. Finally, we give an outlook to future research directions and applications. Advances in bioinspired nanochannel membranes based on polymeric materials will usher opportunities toward osmotic energy conversion, potentially transforming the power output from concept to applications.