In this work, we demonstrate a highly efficient, flexible piezoelectric nanogenerator (PENG) using solid-state synthesized hexagonal boron nitride (hBN) nanoflakes embedded in a polyvinylidene fluoride (PVDF) matrix. The matrix was electrospun to form a piezocomposite (hBN-PVDF) free-standing nanofiber mat to power up wearable electronic devices. X-ray diffraction confirmed the hexagonal structure of boron nitride (hBN), while SEM/TEM images revealed the morphology and lattice fringes, respectively. Fourier transform infrared spectroscopy and Raman spectroscopy were used to study the increase in the piezoelectric behavior due to the increase in the polar β-phase of PVDF with the addition of hBN in the piezocomposite. hBN enhances the piezoelectric coefficient and Young's modulus of PVDF, resulting in the generation of high output voltage in the piezocomposite. The asfabricated piezoelectric nanogenerator efficiently drives the charges generated by mechanical stress to electrodes, producing an outstanding open-circuit voltage (OCV) of ∼68 V and short-circuit current of ∼0.1 μA with a power density of 53.2 μW/cm 2 across a 10 MΩ resistor, which is the highest reported performance so far among the same class of devices. Furthermore, energy is harvested from human movements like finger folding and walking. A piezopotential of ∼98 V generated during walking demonstrates a self-powered pedometer. In addition, a capacitor of 2.2 μF is charged up to ∼3 V by tapping the PENG. The robust, as-fabricated PENG showed untarnished performance even after 45 days of storage and 1500 bending cycles, thus being an ideal choice for scavenging biomechanical energy to power wide range of flexible, wearable and self-powered electronics.
The fabrication of a gel through the selfassembly of a nanoscale metal−organic framework is extremely rare. Here we report the facile synthesis of new hydrogel nanocomposites by the surface coating of ZIF-8 nanoparticles with laponite (LP) nanoclay through electrostatic interaction. The hydrogel exhibits a pHcontrolled release of encapsulated guest molecules. Also, a luminescent hydrogel nanocomposite is prepared by encapsulating dye into ZIF-8, followed by gelation with LP.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.