Augmenting Piezoelectric Performance of Poly (vinylidene fluoride) Nanogenerator with Zinc Oxide Nanorods Decorated Reduced Graphene Oxide Nanosheets

Flexible, lead-free piezoelectric nanogenerators are gaining prominence as viable alternatives with remarkable potential in the backdrop of increasing demand for sustainable energy solutions, particularly in the field of microelectronic systems and sensing technologies. In this context, the synergistic impact of utilizing reduced graphene oxide (rGO) nanosheets decorated with zinc oxide (ZnO) nanorods, in conjunction with a low-temperature phase-inversion technique aimed at augmenting the polar β-phase of poly­(vinylidene fluoride) (PVDF) was explored. The nanofiller concentrations of rGO and ZnO were systematically varied to ascertain the optimal concentration in the PVDF matrix. These optimal concentrations were further used to fabricate PVDF/ZnO/rGO hybrid and PVDF/ZnO-decorated rGO nanocomposites. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC) characterizations were employed to examine the electroactive crystal phase in synthesized nanocomposites, confirming enhancement in polar β-phase and crystallinity, thereby improving piezoelectric, dielectric, and ferroelectric properties of the nanocomposites as confirmed by a dielectric broadband spectrometer (BDS) and piezoresponse force microscopy (PFM). A comparative analysis of optimized nanocomposites supplemented with related characterizations was performed to assess their piezoelectric performance. Additionally, systematic variations in force and frequency were carried out to understand their correlation with the piezoelectric performance of PENGs. The optimized PENG showcased the exceptional piezoelectric energy harvesting potential, generating an open circuit voltage of 23 V (at 1 Hz and 1 N), 98 V (at 5 Hz and 10 N), and 153 V (at 15 Hz and 50 N). Further, the PENG produced an instantaneous power density of ∼28 μW/cm², charged a range of capacitors, sensed human body motions, successfully illuminating 50 LEDs in series and 36 in combination of series and parallel connections. This fabricated PENG henceforth showcases the immense potential for energy harvesting applications.