Clay-Based Nanofluidic Membrane with Enhanced Space Charge for Robust Osmotic Energy Harvesting

Converting the salinity gradient energy into electric energy through permselective membranes has great potential to alleviate the energy crisis. However, the competition between selectivity and permeability, along with the instability of traditional permselective membranes, limits their realistic applications. Herein, a robust clay-based nanofluidic membrane of aramid nanofiber@palygorskite/anodic alumina oxide (ANF@PAL/AAO) with a 3D interworking network has been fabricated for efficient osmotic energy harvesting. The 3D interconnected nanochannels stacked by needle-like PAL provide more and shorter paths for ion transport, thereby increasing the permeability. Moreover, the collaboration between the surface charge of PAL and the space charge brought by ANFs improves ion selectivity, further enhancing the energy conversion performance. Results show that the as-prepared ANF@PAL/AAO membrane displays a power output of 45 W m^–2 at 500-fold NaCl gradient and can withstand acidity/alkalinity and high salinity environments. The present work paves a facile way for the application of clay-based nanofluidic devices in practical energy conversion.