Enhanced Piezoelectric Nanogenerators with Sr-Doped Lanthanum Cobaltite (La_1–<i>x</i>Sr_<i>x</i>CoO₃) and Multiwalled Carbon Nanotubes for Energy Harvesting

Piezoelectric nanogenerators (PENGs) are an efficient source of energy, converting mechanical energy into electrical energy via the ferroelectric effect. To develop self-powered devices that require no external energy sources, a nanogenerator was fabricated, comprising Sr2+-doped lanthanum cobaltite (La1–xSrxCoO3 defined as LSCO) perovskite, polyvinylidene fluoride (PVDF), and multiwalled carbon nanotubes (MWCNT) as supplementary fillers. LSCO was synthesized by a simple molten-salt process, and piezoelectric composite films were prepared through sonication followed by poling and curing. The addition of LSCO to PVDF and further MWCNT in the LSCO/PVDF composite to form piezoelectric films was optimized, and then the composite films were placed between two copper electrodes to fabricate the PENG. Electrical performance of the PENG was investigated and resulted in the enhancement of dielectric, piezoelectric, and energy storage properties. Pristine LSCO-based PENGs produced open-circuit AC peak-to-peak outputs of 25.71 V, 40.3 nA, and 15.919 mW/m2, while Sr doping in the composite showed a remarkable impact. DC voltage was found to be ∼8.2 V for the optimum LSCO/PVDF composite films, which was further improved by 20% due to MWCNT addition tested by a bridge rectifier in a series. At 105 BPM, the PENGs could charge a 3.3 μF capacitor to 1.14 V in about 75 s. Finally, the PENG was used as an energy harvesting device, smart weight sensor, and motion sensor to operate low-power electronic devices.