Clay-Based Nanofluidic Membrane Derived from Vermiculite Nanoflakes for Pressure-Responsive Power Generation

The intrinsic thermal and chemical stability of vermiculite clay is exploited here to fabricate a robust and responsive energy device that consumes atmospheric water molecules as the cathode reagent. A nanofluidic membrane of clay was prepared by reconstructing exfoliated nanolayers of natural vermiculite clay and doped with poly(diallyldimethylammonium chloride) (PDDA). X-ray diffraction studies determined the height of the two-dimensional nanofluidic channels to be ∼0.41 nm. Application of a modest pressure of 56 kPa, on the Al foil placed on top of a PDDA-doped nanofluidic vermiculite membrane (PDDA-VM), yields a stable potential of ∼0.8 V. The output current value of the clay-based devices can be tuned by varying parameters like intercalating cations, device geometry, thickness of the polymeric coating, and applied pressure. The natural clay-based energy device is found to be highly robust; exposure to liquid nitrogen (−195 °C), heat pulse (450 °C), water steams, and mechanical stress (100 N) did not deteriorate its performance. Interestingly, the PDDA-VMs exhibit extraordinary fire retardancy, with ∼70% recovery in the power output after exposure to an open flame.