Nanofiber-reinforced clay-based 2D nanofluidics for highly efficient osmotic energy harvesting

Clay-based 2D nanofluidics are promising candidates for promoting practical application of osmotic energy harvesting owing to their low cost and simple large-scale preparation, but they usually suffer from poor mechanical strength and unsatisfactory ion selectivity. Herein, the nanofiber reinforcement strategy is proposed to address these two key issues of clay-based 2D nanofluidics for achieving highly-efficient osmotic energy harvesting. The aramid nanofibers (ANFs) are intercalated into lameller montmorillonite (MMT) membrane to construct robust 2D nanofluidics. In this configuration, the introduction of negatively-charged ANFs greatly enhances the mechanical strength of MMT nanofluidic membrane, and further improves the cation selectivity towards high-efficient osmotic energy conversion. The ANF-reinforced MMT nanofluidics could delivery a maximum power output up to ~5.16 W m−2 under 50-fold salinity gradient (KCl) simulating sea/river junction environment, which is remarkably superior to almost all reported clay-based 2D nanofluidics. The osmotic power can be further increased to 6.45 W m−2 at a higher temperature of 50 ºC. Furthermore, the 2D nanofluidic membrane can withstand extreme water environments such as strong acidity/alkalinity and high salinity for over 20 days. This work is envisaged to provide a new strategy in the construction of robust clay-based 2D nanofluidics towards pushing osmotic energy harvesting into real-world applications.