Ultranarrow nanochannels in a staggered two-dimensional polymer membrane enhance electric double-layer coverage for osmotic energy harvesting.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42321203.
- Also identified by DOI 10.1038/s41467-026-74696-4 and PMC identifier 13282372.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Two-dimensional framework membranes (2DFMs) hold great promise for sustainable energy-harvesting technologies, yet their performance is often limited by low electric double-layer (EDL) coverage (ƞ<sub>EDL</sub>) arising from large channels and/or low charge densities. Here, we report an ultrathin ( ~ 50 nm), fully crystalline, ABC-stacked viologen-incorporated 2D polymer membrane (sV2DP) featuring vertically aligned triangular nanochannels (D<sub>eff</sub> = 1.36 nm) densely decorated with pyridinium sites ( + 22.4 mC m<sup>-2</sup>). Compared with its non-staggered AA-stacked analogue, sV2DP exhibits a 3.2-fold enhancement in ƞ<sub>EDL</sub> under a 50-fold KCl gradient, combining high anionic selectivity (t<sub>- </sub>= 0.85) with remarkable selective current density (14.6 kA m<sup>-2</sup>). Simulations reveal that spirally arranged charges generate a unique "screw-like" anion migration pathway, significantly enhancing transmembrane efficiency relative to non-staggered 2DP analogues. When integrated into micro-aperture osmotic power generators, the sV2DP membrane delivered a peak power density of 243 W m<sup>-2</sup> under a 50-fold NaCl gradient, placing it among the highest-performing systems.