Processing nanocellulose foam into high-performance membranes for harvesting energy from nature.

Nanocellulose membranes exhibit good stability and high strength. However, the conventional synthetic routes rely on solvent volatilization of a nanocellulose suspension or solution. The complete hydrogen bonding that occurs in this process leads to a dense structure and poor strength in water. Hereby, lignosulfonate and polycation were mixed to form a complex and then attached to cellulose. The freeze-dried nanocellulose foam was hot-pressed to membrane, resulting in simultaneous co-crosslinking and membrane formation. The membrane had a porous structure with a high mechanical performance, excellent stability and a fast shape recovery. This also represents a method for processing functional nanocellulose membranes, as further demonstrated by the hybrid membrane with exceptional solar-driven seawater desalination and water-flow electricity generation properties. This work established facile methods for tackling the structural weakness of the conventional nanocellulose membrane, and opens the door to the application of nanocellulose membrane with a combination of mechanical stability and functionality.