In this work, a synthesis technique for highly homogeneous PVDF-CaFe₂O₄ polymer films direct from solution was developed. The structural characterizations were conducted using XRD, FTIR, and ESEM experimental techniques. The XRD characteristic peaks of CaFe₂O₄ nanoparticles revealed a polycrystalline structure. The average crystallite size for CaFe₂O₄ was calculated to be 17.0 nm. ESEM micrographs of PVDF nanocomposites containing 0.0, 0.25, 0.75, and 1.0 wt% of CaFe₂O₄ showed smooth surface topography. The direct E_dir and indirect E_ind band gap energies for the PVDF-CaFe₂O₄ nanocomposites were decreased with the additions of 0.0–1.0 wt% CaFe₂O₄. In addition, the refractive index (n₀) increased from 3.38 to 10.36, and energy gaps (E_g) decreased from 5.50 to 4.95 eV. The nonlinear refractive index (n₂) for the PVDF-CaFe₂O₄ nanocomposites was improved with the addition of CaFe₂O₄ nanoparticles, exceeding those reported in the literature for PVC, PVA, and PMMA nanocomposites. Therefore, the PVDF-CaFe₂O₄ nanocomposites are expected to take the lead in optoelectronic applications because of their unusual optical properties.

The present work considers the integration of g-C₃N₄ nanosheets into PVC/PVP polymer nanocomposites at ratios of 0.0, 0.3, 0.6, and 1.0 wt%. The XRD data scans showed semicrystalline structures for all PVC/PVP/g-C₃N₄ polymer blend films. The FTIR and Raman measurements revealed intermolecular hydrogen bonding between the g-C₃N₄ surface and the OH⁻ groups of the PVC/PVP network. ESEM morphology analysis for PVC/PVP/g-C₃N₄ nanocomposite films displayed homogeneous surface textures. The data of TGA showed improved thermal stability as the decomposition temperature increased from 262 to 276 °C with the content of g-C₃N₄ (0.0–1.0 wt%). The optical absorbance data for PVC/PVP films improved after the addition of g-C₃N₄. The optical energy gaps showed compositional dependence on the g-C₃N₄ content, which changed from 5.23 to 5.34 eV at indirect allowed transitions. The refractive index for these blend films enhanced (1.83–3.96) with the inclusion of g-C₃N₄. Moreover, the optical susceptibility for these nanocomposite films increased as the content of g-C₃N₄ changed from 0.0 to 1.0 wt%. Finally, the values of the nonlinear refractive index showed improvement with the increased percentage of g-C₃N₄. When g-C₃N₄ was added up to 1.0 wt%, the DC conductivity improved from 4.21 × 10⁻⁸ to 1.78 × 10⁻⁶ S/cm. The outcomes of this study prove the suitable application of PVC/PVP/g-C₃N₄ in optoelectronic fiber sensors.

Polymer blend hybrid nanocomposites are of great importance for future optoelectronic applications. This paper presents the preparation of new polymer blend hybrid nanocomposites based on PVC/PVP modified with Er₂O₃ nanoparticles. A low-cost solution casting method has been used to prepare the polymer nanocomposites at 0.0, 0.1, 0.3 and 0.6 wt% of Er₂O₃. X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, and environmental scanning electron microscopy (ESEM) measurements have all been used to examine the impact of a varying wt% of Er₂O₃ on the structural and optical characteristics of PVP/PVC polymer blends. The PVC/PVP polymer blend and Er₂O₃ nanoparticles showed a strong interaction, which was validated by XRD, FTIR, and Raman spectrum investigations. The SEM micrographs showed a remarkable complexation among the components of the polymer nanocomposites. The activation energies for thermal decomposition of PVC/PVP doped with different Er₂O₃ concentrations were less than that of the pure polymer film. The linear and nonlinear refractive indexes, dispersion energy, optical susceptibility and the energy gap values were found to be Er₂O₃ concentration-dependent. With an increase in Er₂O₃ concentration to 0.1 and 0.3 wt%, the dispersion energy and nonlinear refractive index improved, and thereafter decreased when the concentration was further increased to 0.6For the film doped with 0.1 wt% Er₂O₃, the optical band gap (E_opt) of the composite film enhanced by about 13%. The optical absorption measurements revealed clear improvements with the addition of erbium oxide. Higher refractive index values of PVC/PVP/Er₂O₃ films qualify the polymer blend as a cladding for electro-optic modulators. Our results indicated that the PVC/PVP/Er₂O₃ polymer films could be suitable for optoelectronic space applications.

The nanocomposites of S@g-C₃N₄ and NiS-g-C₃N₄ were synthesized for catalytic hydrogen production from the methanolysis of sodium borohydride (NaBH₄). Several experimental methods were applied to characterize these nanocomposites such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and environmental scanning electron microscopy (ESEM). The calculation of NiS crystallites revealed an average size of 8.0 nm. The ESEM and TEM images of S@g-C₃N₄ showed a 2D sheet structure and NiS-g-C₃N₄ nanocomposites showed the sheet materials that were broken up during the growth process, revealing more edge sites. The surface areas were 40, 50, 62, and 90 m²/g for S@g-C₃N₄, 0.5 wt.% NiS, 1.0 wt.% NiS, and 1.5 wt.% NiS, respectively. The pore volume of S@g-C₃N₄ was 0.18 cm³, which was reduced to 0.11 cm³ in 1.5 wt.% NiS owing to the incorporation of NiS particles into the nanosheet. We found that the in situ polycondensation preparation of S@g-C₃N₄ and NiS-g-C₃N₄ nanocomposites increased the porosity of the composites. The average values of the optical energy gap for S@g-C₃N₄ were 2.60 eV and decreased to 2.50, 2.40, and 2.30 eV as the NiS concentration increased from 0.5 to 1.5 wt.%. All NiS-g-C₃N₄ nanocomposite catalysts had an emission band that was visible in the 410–540 nm range and the intensity of this peak decreased as the NiS concentration increased from 0.5 to 1.5 wt.%. The hydrogen generation rates increased with increasing content of NiS nanosheet. Moreover, the sample 1.5 wt.% NiS showed the highest production rate of 8654 mL/g·min due to the homogeneous surface organization.

In this work, the S@g-C₃N₄ and CuS@g-C₃N₄ catalysts were prepared via the polycondensation process. The structural properties of these samples were completed on XRD, FTIR and ESEM techniques. The XRD pattern of S@g-C₃N₄ presents a sharp peak at 27.2° and a weak peak at 13.01° and the reflections of CuS belong to the hexagonal phase. The interplanar distance decreased from 0.328 to 0.319 nm that facilitate charge carrier separation and promoting H₂ generation. FTIR data revealed the structural change according to absorption bands of g-C₃N₄. ESEM images of S@g-C₃N₄ exhibited the described layered sheet structure for g-C₃N₄ materials and CuS@g-C₃N₄ demonstrated that the sheet materials were fragmented throughout the growth process. The data of BET revealed a higher surface area (55 m²/g) for the CuS-g-C₃N₄ nanosheet. The UV–vis absorption spectrum of S@g-C₃N₄ showed a strong peak at 322 nm, which weakened after the growth of CuS at g-C₃N₄. The PL emission data showed a peak at 441 nm, which correlated with electron–hole pair recombination. The data of hydrogen evolution showed improved performance for the CuS@g-C₃N₄ catalyst (5227 mL/g·min). Moreover, the activation energy was determined for S@g-C₃N₄ and CuS@g-C₃N₄, which showed a lowering from 47.33 ± 0.02 to 41.15 ± 0.02 KJ/mol.

The synthesis of CaCO₃/Cu₂O/GO nanocomposites was developed by sol-gel auto-combustion method. The analysis of structure was completed on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and environmental scanning electron microscopy (ESEM). The XRD spectra of the nanocomposites matched the crystal structure of CaCO₃/Cu₂O. The average crystal size was 20 nm for Cu₂O and 25 nm for CaCO₃ nanoparticles. FTIR data showed the absorption bands of Cu₂O and GO. Raman spectroscopy data confirmed the formation of GO sheets. ESEM micrographs displayed spherical nanoparticles dispersed in GO sheets. X-ray photoelectron spectroscopy showed the peaks of Cu 2p, O 1s, C 1s, Cu 3s, and Ca 2p. The spectra of optical absorption revealed an absorption band of around 450 nm. The calcium content increase led to a decrease in the optical energy gap from 2.14 to 1.5 eV. The production of hydrogen from NaBH₄ across the methanolysis reaction was accelerated by the CaCO₃/Cu₂O/GO nanocomposites. Therefore, these nanocomposites are superior in catalytic hydrogen production systems.