A hybrid microwave sintered PZT composite as a flexible piezoelectric nanogenerator

Interest in piezoelectric nanogenerators has grown extensively due to high piezoelectric coefficients. Piezoelectric ceramic-based devices have dominated research in large-scale energy harvesting. Morphotropic phase boundary PbZr_0.52Ti_0.48O₃ (MPB-PZT) synthesized using Hybrid Microwave Sintering (HMS) at a low temperature (940 °C) for 20 min has emerged as a dense ceramic. The Rietveld refinement studies confirm its dual phase (tetragonal (P4mm) and rhombohedral (R3m)). The PZT ceramic is exploited as a piezoelectric material, which can improve the output piezoelectric potential of a piezoelectric nanogenerator (PENG). Multi-walled carbon nanotubes (MWCNTs) are evenly distributed in the PZT composite to reduce the internal resistance of the PENG. According to the percolation theory, small amounts of MWCNTs dispersed within the composite ink can significantly improve the output voltage of the PENG by acting as conductive bridges between the polymer (polyvinylpyrrolidone (PVP)) and ceramic particles. The concentration of PZT and the amount of MWCNTs are changed to enhance the device's output voltage. As a result, an optimized PENG with a PZT (1.5 g)/MWCNT (0.06 wt%)/PVP (4 g) (PVP - polyvinylpyrrolidone) composite film is obtained. The PENGs are mechanically poled. The optimised output voltage of the PENG is 16 Vpp, which could light up a series of 20 commercial light emitting diodes (LEDs). The PENG is attached to footwear and is noticed to efficiently harvest energy from daily human activities which demonstrate its practical applications.