Bio‐inspired Double Angstrom‐Scale Confinement in Ti‐deficient Ti0.87O2 Nanosheet Membranes for Ultrahigh‐performance Osmotic Power Generation

Abstract

AbstractOsmotic power, a clean energy source, can be harvested from the salinity difference between seawater and river water. However, the output power densities are hampered by the trade‐off between ion selectivity and ion permeability. Here we propose an effective strategy of double angstrom‐scale confinement (DAC) to design ion‐permselective channels with enhanced ion selectivity and permeability simultaneously. The fabricated DAC‐Ti0.87O2 membranes possess both Ti atomic vacancies and an interlayer free spacing of ≈2.2 Å, which not only generates a profitable confinement effect for Na+ ions to enable high ion selectivity but also induces a strong interaction with Na+ ions to benefit high ion permeability. Consequently, when applied to osmotic power generation, the DAC‐Ti0.87O2 membranes achieved an ultrahigh power density of 17.8 W m−2 by mixing 0.5/0.01 M NaCl solution and up to 114.2 W m−2 with a 500‐fold salinity gradient, far exceeding all the reported macroscopic‐scale membranes. This work highlights the potential of the construction of DAC ion‐permselective channels for two‐dimensional materials in high‐performance nanofluidic energy systems.