Cement-and-pebble nanofluidic membranes with stable acid resistance as osmotic energy generators

Abstract

Osmotic energy between river water and seawater has attracted interest as a new source of sustainable energy. Nanofluidic membranes in a reverse electrodialysis configuration can capture energy from salinity gradients. However, current membrane materials suffer from high resistances, low stabilities, and low charge densities, which limit their further application. Here, we designed a high-performance nanofluidic membrane using carboxylic cellulose nanofibers functionalized with graphene oxide nanolamellas with cement-and-pebble microstructures and stable skeletons for enhanced ion transmembrane transport. By mixing artificial river water and seawater, the composite membrane achieved a high output power density up to 5.26 W m−2. Additionally, the membrane had an excellent acid resistance, which enabled long-term use with over 67 W m−2 of power density. The performance of this composite membrane benefited from the mechanically strong cellulose fibers and the bonding between nanofibers and nanolamellas. In this work, we highlight promising directions in industrial waste treatment using energy extracted from chemical potential gradients.