High-Density 1D Ionic Wire Arrays for Osmotic Energy Conversion.

Osmotic energy, existing between the seawater and river water, is a renewable energy source, which can be directly converted into electricity by ion-exchange membranes (IEM). In traditional IEMs, the ion transport channels are formed by nanophase separation of hydrophilic ion carriers and hydrophobic segments. It is difficult to realize high-density ion channels with controlled spatial arrangement and length scale of ion carriers. Herein, we construct high-density 1D ion wires as transmission channels. Through molecular design, hydrophilic imidazole groups and hydrophobic alkyl tails were introduced into the repeat units, which self-assembled into 1D ion transporting core and protecting shell along the main chains. The areal density of the ionic wire arrays is up to ~ 1012 cm-2, which is the highest value. The ionic wires ensure both high ion flux transport and high selectivity, achieving an ultrahigh-power density of 40.5 W m-2 at a 500-fold salinity gradient. Besides, the ionic wire array membrane is well recyclable and antibacterial. The ionic wires provide novel concept for next generation of high-performance membranes.