Osmotic energy generation with mechanically robust and oppositely charged cellulose nanocrystal intercalating GO membranes

Nanofluidic channel constructed using two-dimensional(2D) material is a promising system for harvesting blue energy from nature. Current systems using stacks of 2D nanosheets possess high ion selectivity but suffer from poor mechanical strength and low power density. The intercalation of nanofibers into 2D membrane system could enhance the structural stability and provide additional space charge for ions transport, while the agglomeration of micro-scale polymer chain resulted in steric hinderance inside the nanochannel. Herein, we describe a high performance nanofluidic osmotic generator (NOG) prepared using an oppositely charged cellulose nanocrystal (CNC)/graphene oxide (GO) composite membrane system. Small amounts of intercalated nanosized CNC could reinforce the structural stability and minimized transmembrane energy barrier. Functionalized CNCs provided an efficient space charge without introducing physical resistance, contributing to the excellent power generation performance. In 50-fold salinity gradient, the NOG produced an output power density of 4.73 W m−2 at room temperature that increased to 10.92 W m−2 at 337 K, which was higher than most of state-of-art membrane based osmotic power generator.