Temperature-gated nanocellulose membrane for enhanced and controllable osmotic energy harvesting

Reverse electrodialysis system (REDs) based on nanochannels membrane has been widely investigated for high-performance osmotic energy harvesting. However, restricted by the non-renewable, low power density, and uncontrolable ion transport of membrane materials, the existing membrane-based REDs are usually unregulated and unintelligent, which greatly prohibits their practical applications. Herein, a temperature-gated nanochannels membrane is constructed by the functionalized Cladophora nanocellulose for controllable osmotic energy harvesting, in which the thermo-responsive nanocellulose is obtained by grafting with poly(N-isopropylacrylamide) (PNIPAM) brushes via the atom-transfer radical polymerization (ATRP) method. Based on this membrane, the output from the osmotic energy harvesting system can be regulated and boosted by alternating the temperature switches reversibly and stably. A maximum power density up to approximately 10.1 W/m2 is achieved under a 50-fold salinity gradient at 50 °C, which is remarkably superior to most of the reported cellulose-based nanofluids. Besides, the REDs based on this membrane is designed as a self-powered flexible and wearable thermometer, which can be employed to detect human health. Overall, this strategy first develops cellulose-based nanochannels membrane with both intelligent response and enhanced energy output, which anticipates the wide potential for pushing the osmotic energy into real-world applications.