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

## TL;DR

A new membrane with high-density 1D ionic wires efficiently converts osmotic energy and resists swelling and bacteria.

## Contribution

A self-assembled homopolymer creates high-density 1D ionic channels with both high ion selectivity and conductivity.

## Key findings

- The membrane achieves a power density of 40.5 W m⁻² under a 500-fold salinity gradient.
- The membrane shows minimal swelling (<10%) and excellent antibacterial properties.
- The ionic wire arrays have an ultrahigh density of ~10¹² cm⁻².

## Abstract

Ultrahigh-Density 1D Ionic Wire Arrays. A high density (~1012 cm−2) of 1D ionic channels is achieved via self-assembly of a homopolymer, enabling simultaneous high ion selectivity and conductivity for efficient osmotic energy conversion.
Anti-Swelling Membrane with Superior Performance. The membrane exhibits an ultrahigh ion-exchange capacity (~2.69 meq g−1) yet minimal swelling (<10%) due to hydrophobic alkyl shell protection, leading to a breakthrough power density of 40.5 W m⁻² under a 500-fold salinity gradient.Multifunctional Design with Antibacterial Properties. The imidazole-functionalized membrane not only enhances osmotic energy harvesting but also provides excellent antibacterial performance, offering a novel strategy for advanced separation membranes.

Ultrahigh-Density 1D Ionic Wire Arrays. A high density (~1012 cm−2) of 1D ionic channels is achieved via self-assembly of a homopolymer, enabling simultaneous high ion selectivity and conductivity for efficient osmotic energy conversion.

Anti-Swelling Membrane with Superior Performance. The membrane exhibits an ultrahigh ion-exchange capacity (~2.69 meq g−1) yet minimal swelling (<10%) due to hydrophobic alkyl shell protection, leading to a breakthrough power density of 40.5 W m⁻² under a 500-fold salinity gradient.

Multifunctional Design with Antibacterial Properties. The imidazole-functionalized membrane not only enhances osmotic energy harvesting but also provides excellent antibacterial performance, offering a novel strategy for advanced separation membranes.

The online version contains supplementary material available at 10.1007/s40820-025-01976-x.

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.

The online version contains supplementary material available at 10.1007/s40820-025-01976-x.