Reinforcement of structural, optical, electrical, and dielectric characteristics of CMC/PVA based on GNP/ZnO hybrid nanofiller: Nanocomposites materials for energy-storage applications

Abstract

Polymer hybrid nanocomposites films of carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA)/graphene nanoplatelets (GNP) incorporated with varying concentrations of nano-zinc oxide (ZnO) were fabricated using the solution casting method. The effect of the GNP/ZnO hybrid nanofiller on structural, optical, and conductive characteristics of the pristine CMC/PVA polymer was studied and discussed. The X-ray diffraction findings reveal that the crystallinity of the nanocomposites films decreases with increasing GNP/ZnO-NPs content. Fourier transform infrared spectra indicate the interaction between CMC/PVA polymer chains and GNP/ZnO nanohybrid. The optical absorption spectrum demonstrates that the energy gap decreases as the amount of GNP/ZnO nanofiller increases. In the dielectric characteristics, space charge polarization was shown by the high values of ε' at low frequencies, whereas, higher values of ε″ were associated with an increase in energy loss in the composite films. The increasing conductivity with frequency was described in the light of hopping and Koop's theory. After loading the GNP/ZnO-NPs, the conductivity increased due to an enhancement in the charge carriers. The correlated barrier hopping model was shown to be the conduction mechanism that dominates nanocomposite films with the non-Debye relaxation process. These outcomes demonstrate the suitability of these nanocomposites for various applications including flexible capacitors, separators in batteries, and energy storage devices.