Al₂O₃-Decorated Reduced Graphene Oxide Composite for Flexible Piezoelectric Energy-Harvesting Applications

An Al₂O₃/reduced graphene oxide (rGO)-incorporated polyvinylidenefluoride (PVDF) nanocomposite was synthesized in a two-step hydrothermal process to fabricate a piezoelectric nanogenerator (PENG). During the second-step hydrothermal process, the graphene oxide (GO) was converted to rGO and made a composite with Al₂O₃ to produce the Al₂O₃/rGO nanocomposite, in which the rGO nanosheets were found to be well decorated with the Al₂O₃ nanoparticles. Further, the Al₂O₃/rGO was incorporated in different weight percentages in PVDF through solution-casting to fabricate self-standing polymeric nanocomposite films. Detailed structural, morphological, and electrical characterizations of the composite films were carried out. In order to fabricate the piezoelectric PENG device a 0.5 wt.% Al₂O₃-rGO/PVDF nanocomposite film was used. The PENG device exhibited an open circuit voltage of about 44 V and a significant high-power density of 8.25 mW/cm³ against a load resistance of 2 MΩ. An electrostatic capacitor of 4.7 µF was charged up to 14 V using the fabricated device within 600 s. This output was obtained by simple finger tapping of the PENG device. The results were found to be quite reliable and the device was significantly robust, making the reported material fairly suitable for real-life applications targeting the Internet of Things and wearable electronics.