Substantial enhancement of the electroactive phase and dielectric properties at low loading levels of SnO2/MXene nanocomposite as a novel nanofiller in the PVDF matrix

Herein, we investigate the impact on electroactive phase and dielectric properties of polyvinylidene fluoride (PVDF) on addition of hydrothermally synthesized SnO2/MXene (SNMX) nanocomposite with different concentration (0.25 wt%, 0.50 wt%, 0.75 wt%) as nanofillers. The pure and SNMX/PVDF composite films were fabricated using solution casting method. Morphological and structural analyses revealed a modified spherulitic structure, indicating a transformation from the non-polar phase (52 %) to the polar ((3 + gamma) phase (86 %). The dielectric measurements were conducted over a frequency range of 20 Hz to 1 MHz at different operating temperature to examine the various relaxations occurring in the polymer. At 25 degrees C and an applied field frequency of 20 Hz, the relative dielectric permittivity of the SNMX/PVDF composite film (0.75 wt%) elevates approximately 25-fold relative to the pristine PVDF film, with a concomitant reduction in loss tangent. Further, the relative dielectric permittivity of all films intensifies with rising operating temperature. At 100 degrees C, the relative dielectric permittivity amplifies from 165 to 250 compared to room temperature for the 0.75 wt% nanofiller concentration. The increment in dielectric properties with addition of SNMX are attributed to a) the enhancement of the electroactive phase, which favours molecular reorientation, b) the presence of SnO2 semiconductive layer on the surface of MXene flakes that prevent formation of conductive pathways, thus improves the interfacial polarization through the Maxwell-Wagner-Sillars (MWS) effect in addition to dipolar polarization. A piezoelectric flexible nanogenerator (PENG) fabricated from the 0.75 wt% SNMX/PVDF nanocomposite film generated a maximum peak to peak voltage is 105 V.