A flexible self-poled piezoelectric nanogenerator based on a rGO–Ag/PVDF nanocomposite

Abstract

Here we demonstrate the mechanical energy harvesting performance of a poly(vinylidene-fluoride) (PVDF) device which is loaded with reduced graphene oxide–silver nanoparticles (rGO–Ag). The current results show that the addition of rGO–Ag enhances the polar beta and gamma piezoelectric phases in PVDF, which is capable of generating a greater piezoelectric output, thereby eliminating the requirement of any external poling process. X-ray diffraction (XRD) and Fourier transform infra-red spectroscopy (FT-IR) characterizations were employed for the identification and quantification of the piezoelectric polar phases of the nanocomposite films. Raman spectroscopy confirmed the interactions between rGO–Ag and PVDF. Polarization vs. electric field (P–E) loop testing was performed and it was found that on the application of an external electric field of 148 kV cm⁻¹ the nanocomposite showed an energy density value of ∼0.26 J cm⁻¹, which indicates its potential for energy storage applications. The fabricated energy harvesting device, a piezoelectric nanogenerator (PNG), could charge up capacitors and light up to 20 commercial blue light-emitting diodes. The PNG was tested to harvest biomechanical energy from pulsing mechanical energy by fixing it to fingers on the human palm. The PNG was also fixed to flip-flops in order to demonstrate its footwear connected energy harvesting application. The PNG showed a peak output open circuit voltage of ∼18 V and a short circuit current of ∼1.05 μA, with a peak power density of 28 W m⁻³ across a 1 MΩ resistor. The PNG shows a moderate efficiency of 0.65%.