Enhancement of Structural, Optical, and Electrical Properties of Hydroxypropyl Methylcellulose/Polyvinyl Alcohol Nanocomposites by Nickel Ferrite Nanoparticles for Optoelectronic Applications

This study investigates the potential of nickel ferrite nanoparticles (NiFe₂O₄ NPs) to improve the structural, optical, magnetic, and electrical properties of a blend of hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) for energy storage applications. NiFe₂O₄ NPs were synthesized using a co-precipitation method and subsequently dispersed within the HPMC/PVA matrix via solution casting to create nanocomposite films. XRD analysis revealed a decrease in crystallinity within the HPMC/PVA blend upon the incorporation of NiFe₂O₄ NPs. FT-IR spectroscopy identified characteristic vibrational peaks that shifted in intensity with increasing NiFe₂O₄ concentration, suggesting interactions between the nanoparticles and the polymer matrix. UV-Vis measurements showed a rise in absorbance of the nanocomposites with increasing NiFe₂O₄ content. The bandgap energy (Eg) decreased with increasing nanofiller concentration. This trend was evident for both direct transitions, which decreased from 5.07 eV to 4.10 eV, and indirect transitions, which dropped from 4.57 eV to 3.44 eV. Impedance spectroscopy studies demonstrated a significant enhancement in AC electrical conductivity, dielectric loss, and dielectric constant of the nanocomposites with increasing NiFe₂O₄ content. There was a substantial increase in direct current conductivity (σdc) from 3.29 × 10^− 11 S/cm to 1.16 × 10^− 9 S/cm, accompanied by a decrease in the frequency exponent (s) from 0.82 to 0.52. Vibrating sample magnetometry (VSM) measurements confirmed the ferromagnetic nature of the nanocomposite films, with magnetic parameters exhibiting a strong dependence on the NiFe₂O₄ concentration. These findings suggest that the biodegradable HPMC/PVA-NiFe₂O₄ nanocomposites hold promise as advanced materials for optoelectronic devices and capacitive energy storage systems due to their combined structural, optical, magnetic, and electrical properties.