Massively Enhanced\nCharge Selectivity, Ion Transport,\nand Osmotic Energy Conversion by Antiswelling Nanoconfined Hydrogels

Developing a nanofluidic membrane with simultaneously\nenhanced\nion selectivity and permeability for high-performance osmotic energy\nconversion has largely been unexplored. Here, we tackle this issue\nby the confinement of highly space-charged hydrogels within an orderedly\naligned nanochannel array membrane. The nanoconfinement effect endows\nthe hydrogel-based membrane with excellent antiswelling property.\nFurthermore, experimental and simulation results demonstrate that\nsuch a nanoconfined hydrogel membrane exhibits massively enhanced\ncation selectivity and ion transport properties. Consequently, an\namazingly high power density up to ∼52.1 W/m<sup>2</sup> with\nan unprecedented energy conversion efficiency of 37.5% can be reached\nby mixing simulated salt-lake water (5 M NaCl) and river water (0.01\nM NaCl). Both efficiency indexes surpass those of most of the state-of-the-art\nnanofluidic membranes. This work offers insights into the design of\nhighly ion-selective membranes to achieve ultrafast ion transport\nand high-performance osmotic energy harvesting.