Interfacial supramolecular interactions regulated oligomer networking into robust sub-nanochannels for efficient osmotic energy conversion

Abstract

Oligomer-engineered membranes overcome fundamental limitations in blue energy harvesting by synergistically controlling ion selectivity and flux at the molecular scale. Here, we develop a 5-nm-thick sulfonated membrane fabricated through interfacial supramolecular assembly of tailored oligomers, which addresses key challenges of conventional polymer membranes: the permeability–selectivity trade-off, energy loss in long nanochannels, and inconsistent performance in hypersaline environments. The ultrathin membrane achieves a power density of 10.8 W m⁻² with 30-day operational stability under a 50-fold NaCl gradient—more than doubling commercial benchmarks (5 W m⁻²), while maintaining high efficiency (30.7 W m⁻²) with hypersaline salt-lake brines. This exceptional performance stems from our synergistic design innovations: sub-Debye-length nanoconfinement (0.6 ± 0.2 nm), creating unscreened electric fields for cation-selective transport while excluding anions, programmable chemical heterogeneity enabling surface charge-directed ion transport, and ultrashort pathways (∼5 nm) that minimize energy dissipation without compromising selectivity. This work establishes a new framework for nano-confined ion transport, advancing sustainable energy harvesting and redefining the design principles for next-generation separation technologies.