Magnetic field assisted high performance triboelectric nanogenerators based on P(VDF-HFP)/NiFe₂O₄ nanofiber composite

Triboelectric nanogenerators (TENGs), which are powered by Maxwell's displacement current, have a wide range of applications, including energy harvesting and self-powered sensors. However, very little attention has been paid to the effect of the ferromagnetic medium on TENG displacement current. Herein, flexible ferrimagnetic poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP))/nickel ferrite (NiFe2O4) fiber composite film based TENGs were fabricated and their performances were analysed. Highly crystalline, ferrimagnetic NiFe2O4 nanofibers with high aspect ratio were prepared using electrospinning technique by systematic optimization of spinning parameters. Thereafter, the fibers were reinforced into the polymeric matrix to improve the beta-phase and dielectric constant which in turn significantly enhanced the TENG performance. The beta-phase enhancement in the composite films was confirmed by XRD and FTIR analysis; 77 % of the beta-phase was achieved with the incorporation of NiFe2O4 fiber. Morphological features were examined using SEM and AFM, which revealed more beta-phase spherulite formation in the composite films. A notable increase in the dielectric properties was evidenced with the addition of NiFe2O4 fibers and a maximum dielectric constant of similar to 26 was attained at 100 Hz. The TENG was developed using P(VDF-HFP)/NiFe2O4 and nylon which generated an output voltage (V-pp) and current (I-pp) values of 584 V and 25 mu A, respectively. Furthermore, the performance of TENG under an external magnetic field was examined, and a notable improvement in performance was observed, paving the way for the application of NiFe2O4 fibers in hybrid energy harvesters and self-powered sensors.