Confined ionic liquid-mediated cation diffusion through layered membranes for high-performance osmotic energy conversion.

Ion-selective membranes act as the core components in osmotic energy harvesting, but remain the deficiency such as low ion selectivity and tendency to swell. Two-dimensional (2D) nanofluidic membranes as competitive candidates are still subjected to limited mass transport brought by insufficient wetting and poor stability in water. Here, we report ionic liquid-infused graphene oxide (GO@IL) membrane with ultrafast ion transport ability and reveal how confined ionic liquid mediates selective cation diffusion. The infusion of ionic liquids endows the 2D membrane with excellent mechanical strength, anti-swelling properties, and good stability in aqueous electrolytes. Importantly, immiscible ionic liquids also provide a medium, allowing partial dehydration for ultrafast ion transport. Through molecular dynamics simulation and finite element modeling, we prove that GO nanosheets induce ionic liquids to rearrange, bringing in additional space charges, which can be coupled with GO synergistically. By mixing 0.5/0.01 M NaCl solution, the power density can achieve a record value of approximately 6.7 W m -2 , outperforming state-of-art GO-based membranes. This work opens up a new route for boosting nanofluidic energy conversion because of the diversity of the ILs and 2D materials. This article is protected by copyright. All rights reserved.