Multifunctional films of poly(vinylidene fluoride)/ZnFe2O4 nanofibers for nanogenerator applications

Abstract

A two-step synthesis method was used to prepare a flexible PVDF/ZnFe2O4 multiferroic nanocomposite film. ZnFe2O4 nanofibers synthesized using electrospinning technique were incorporated into a PVDF matrix to form PVDF/ZnFe2O4 composite films through the solution-casting process. XRD patterns confirmed the formation of the polar β-phase in films, which is responsible for ferroelectricity. The percentage of the β-phase, calculated by FTIR analysis, reached 88% with the incorporation of ZnFe2O4 in PVDF. The transformation of α to β-phase microstructure were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The dielectric constant and tangent loss of the composites with respect to ZnFe2O4 loading were measured. The dielectric constant increase with the increasing concentration of ZnFe2O4, and a maximum value of 30 was obtained for a ZnFe2O4 concentration of 15 wt%. Ferroelectric properties were analyzed by taking into consideration the domain switching behavior, which was investigated by dynamic contact electrostatic force microscopy (DC-EFM), whereas the magnetic properties were analyzed using magnetic force microscopy (MFM). The as-synthesized composite films were further used to fabricate a nanogenerator, which was capable of generating up to 7 V (peak–peak) as a maximum open circuit voltage for a 15 wt% ZnFe2O4-loaded film at 1.5 N of applied force. In addition, the nanogenerator delivered an output power of 4 μW at a load resistance of 500 kΩ, and the results were compared with previous results.