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<p>Flexible hybrid nanocomposite films based on poly(vinyl alcohol) (PVA) containing cobalt-doped ferrite quantum dots (Co-ferrite-QDs) and graphene oxide (GO) were developed via a solution-casting approach with variable nanofiller loading (1–4&#xa0;wt.%) to improve the structural, optical, and shielding parameters. X-ray diffraction (XRD) analysis shows that increasing GO reduces the crystallite size from ~4.76&#xa0;nm to ~3.61&#xa0;nm (Scherrer) while raising micro-strain from ~ 42.7 × 10<sup>−3</sup> to ~ 56.1 × 10<sup>−3</sup> and dislocation density from ~ 4.41 × 10<sup>16</sup>&#xa0;m<sup>−2</sup> to ~ 7.65 × 10<sup>16</sup>&#xa0;m<sup>−2</sup>. The degree of crystallinity improves significantly from 70.3% to 85.7%, accompanied by higher stress (18.97&#xa0;MPa → 24.92&#xa0;MPa), Young’s modulus, and energy density (293&#xa0;kJ&#xa0;m<sup>−3</sup> → 939&#xa0;kJ&#xa0;m<sup>−3</sup>), confirming efficient reinforcement through strong interfacial interactions. Analysis of the surface morphology reveals good dispersion at low loading, with partial aggregation at the highest fraction, and elemental signatures verify stable incorporation of the ferrite phase. Ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy results reveal intensified attenuation across the UV–visible range together with a systematic bandgap reduction from 5.0&#xa0;eV to 3.13&#xa0;eV. In parallel, the refractive index increases from 1.09213 to 1.14845 with a decrease in optical electronegativity (0.601–0.475), and broadening of Urbach energy from 1.947&#xa0;eV to 2.528&#xa0;eV, indicating enhanced polarizability and increased density of localized states. Moreover, GO incorporation enhances the frequency-dependent refractive index, optical dielectric function, and optical conductivity while reducing skin depth markedly, signifying potential for use in electromagnetic interference (EMI) shielding. Fourier transform infrared (FTIR) spectroscopy analysis confirms effective interfacial interactions and successful integration of Co-doped ferrite and GO within the PVA matrix, validating the formation of a well-hybridized nanocomposite structure. The tunability of these parameters demonstrates that small variations in GO content enable precise control over stiffness and light–matter interaction, positioning these nanocomposite films as attractive materials for optoelectronic applications.</p>

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Improving Structural, Surface, and Tunable Optical Properties of PVA/Co-Ferrite-QDs/GO Nanocomposites

  • 期刊论文

  • 发表日期：

    2026年7月16日

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  • Parvez Ali,
  • P. A. Alvi

摘要

Flexible hybrid nanocomposite films based on poly(vinyl alcohol) (PVA) containing cobalt-doped ferrite quantum dots (Co-ferrite-QDs) and graphene oxide (GO) were developed via a solution-casting approach with variable nanofiller loading (1–4 wt.%) to improve the structural, optical, and shielding parameters. X-ray diffraction (XRD) analysis shows that increasing GO reduces the crystallite size from ~4.76 nm to ~3.61 nm (Scherrer) while raising micro-strain from ~ 42.7 × 10−3 to ~ 56.1 × 10−3 and dislocation density from ~ 4.41 × 1016 m−2 to ~ 7.65 × 1016 m−2. The degree of crystallinity improves significantly from 70.3% to 85.7%, accompanied by higher stress (18.97 MPa → 24.92 MPa), Young’s modulus, and energy density (293 kJ m−3 → 939 kJ m−3), confirming efficient reinforcement through strong interfacial interactions. Analysis of the surface morphology reveals good dispersion at low loading, with partial aggregation at the highest fraction, and elemental signatures verify stable incorporation of the ferrite phase. Ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy results reveal intensified attenuation across the UV–visible range together with a systematic bandgap reduction from 5.0 eV to 3.13 eV. In parallel, the refractive index increases from 1.09213 to 1.14845 with a decrease in optical electronegativity (0.601–0.475), and broadening of Urbach energy from 1.947 eV to 2.528 eV, indicating enhanced polarizability and increased density of localized states. Moreover, GO incorporation enhances the frequency-dependent refractive index, optical dielectric function, and optical conductivity while reducing skin depth markedly, signifying potential for use in electromagnetic interference (EMI) shielding. Fourier transform infrared (FTIR) spectroscopy analysis confirms effective interfacial interactions and successful integration of Co-doped ferrite and GO within the PVA matrix, validating the formation of a well-hybridized nanocomposite structure. The tunability of these parameters demonstrates that small variations in GO content enable precise control over stiffness and light–matter interaction, positioning these nanocomposite films as attractive materials for optoelectronic applications.