Bio-inspired nanocomposite membranes for osmotic energy harvesting

Osmotic energy is a renewable energy with zero emissions and minimal daily variations. However, the membranes for osmotic energy harvesting must have multiple properties that are thought to be impossible to realize to make this technology viable. Here, we show that cartilage-inspired cation-selective composite membrane assembled from aramid nanofibers and boron nitride nanosheets make it possible by a layer-by-layer assembly technology. The osmotic energy can be harvested by both salt concentration gradient and pressure-driven streaming because of the high mechanical and transport characteristics of the membranes. The combination of high strength, toughness, chemical resilience, rapid ion transport, and structural versatility of aramid-boron nitride composites makes it a promising candidate for osmotic energy harvesting under realistic operational conditions and life-cycle requirements.