Design and Characterization of a PDMS/BCT/Multiwalled Carbon Nanotube Nanocomposite as a Piezoelectric Energy Harvester

Polymer composites based on lead-free piezoelectric ceramics have attracted substantial interest recently due to their flexibility, simple shape ability, and the possibility of constructing wearable energy harvesters with high piezoelectric performance. Incorporating lead-free piezoelectric materials into their designs, they offer an eco-friendly alternative to ceramics such as lead zirconate titanate. This solution delivers impressive piezoelectric coefficients without the use of harmful toxins. In this paper, flexible piezoelectric nanogenerators (PENGs) were made using sol–gel synthesized nanoparticles of Ba 0.8 Ca 0.2 TiO 3 (BCT) that are free from lead. BCT samples were subjected to X-ray diffraction (XRD) to examine their crystallinity. The Rietveld refinement of the structural data demonstrates that the synthesized BCT samples crystallize with tetragonal symmetry. In this paper, polydimethylsiloxane (PDMS)-based composites filled with BCT were first prepared using solution mixing methods to realize nanogenerators. To enhance the performance of the nanogenerator (NG), conductive carbon nanotube nanoparticles were used. XRD, Fourier transform infrared, and scanning electron microscopy were performed to examine the crystallinity of particle distribution with PDMS and the homogeneity of the composite. The nanogenerator’s resistive and capacitive behaviors were characterized by utilizing impedance spectroscopy in the frequency range (40 Hz to 1 MHz). The impedance spectra were fitted to determine the equivalent circuit and to study deeply the homogeneity of the realized composites. The 15 wt % BCT + 0.5 wt % MWCNT/PDMS nanogenerator is the most capacitive and is almost homogeneous, as shown by the α parameter of the constant phase element at 0.996. The realized PENGs show good flexibility, homogeneity, and robustness to efficiently harvest energy, especially for composites containing multiwalled carbon nanotubes (MWCNTs). An enhanced output voltage of approximately 2.58 V is achieved by integrating MWCNTs, resulting in a maximum output power of 0.40 μW at 2 MΩ. This performance improvement is owed to the hybridization of the composite with MWCNTs, specifically at the percolation threshold. The addition of MWCNTs facilitates charge transfer between BCT particles due to the enhanced conductivity as well as the improved mechanical properties and piezoceramic particle distribution. This nanogenerator illustrates excellent performance with 15 V output voltage under gentle tapping and 18.4 V under walking as well as excellent stability over 13,000 cycles of repetitive load, which promotes their use of low-powered wearable sensors.