Linear and nonlinear optical investigations of polyvinyl chloride modified La2O3 nanocomposite films

In the present work, we report the effect and improvement of PVC polymer blend nanocomposites performance with addition of lanthanum oxide (La2O3) nanofiller. The structural properties of the samples were studied using different characterization techniques such as XRD, FTIR, Ramman and SEM. The X-ray diffraction peaks of La2O3 are with agreement with the pure hexagonal phase. The La2O3 sample was found to have crystallites size with an average about 15 nm. XRD, FTIR and SEM analysis confirmed the interaction of PVC/La2O3 polymer nanocomposites. The obtained band gaps of PVC/La2O3 polymer nanocomposites decreased (5.72 – 5.0 eV) upon increasing the nanofiller content. The obtained values of single oscillator energy (E0) showed a decrease (5.88 – 3.28 eV) while dispersion energy (Ed) increases (5.64 – 7.20 eV) upon increasing the concentration of La2O3. The estimated values of static refractive index (n0) showed an increase (1.40 – 1.79) upon increasing the percentage of La2O3. Moreover, the nonlinear refractive index (n2) value was changed from 1.56 10−13 to 33.56 x 10−13 esu. Finally, the addition of La2O3 nanofillers increase the polarizability of the polymer molecules and hence the nonlinear refractive index

A Comprehensive Study of Structural, Thermal, and Dielectric Properties of Melt-Processed Polypropylene/Ni0.9Zn0.1Fe2O4 Nanocomposites

This article explores the processing of structural, thermal, and dielectric properties of polypropylene (PP) polymer nanocomposites modified with Ni0.9Zn0.1Fe2O4. The PP/Ni0.9Zn0.1Fe2O4 nanocomposites are manufactured by the melt-processing method using a Brabender Polyspeed B. The XRD and FTIR structural investigations assure good incorporation of Ni0.9Zn0.1Fe2O4 into the PP matrix. It should be noted that adding Ni0.9Zn0.1Fe2O4 NPs to the PP polymer matrix enhances the polymer’s thermal stability. Utilizing the Coats–Redfern model, kinetic thermodynamic parameters such as activation energy (Ea), enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG*) are deduced from TGA data. The dielectric results showed an increase in ε′ with the introduction of nanoparticles into the PP matrix. As the content of Ni0.9Zn0.1Fe2O4 NPs in these nanocomposite films increases, the loss tangent values decrease at higher frequencies while increasing at lower frequencies. The estimated εs and ε∞ of PP nanocomposites using Cole–Cole plots reveal an improvement when NPs are added to PP. We believe that the proposed work suggests a relevant step towards the practical application of PP/Ni0.9Zn0.1Fe2O4 nanocomposites

Three distinct conductance states in polycyclic aromatic hydrocarbon derivatives

Tight-binding model (TBM) and density functional theory (DFT) calculations were employed. Both simulations have demonstrated that the electrical conductance for eight polycyclic aromatic hydrocarbons (PAHs) can be modulated by varying the number of aromatic rings (NAR) within the aromatic derivatives. TBM simulations reveal three distinct conductance states: low, medium and high for the studied PAH derivatives. The three distinct conductance states suggested by TBM are supported by DFT transmission curves, where the low conductance evidenced by T(E) = 0, for benzene, naphthalene, pyrene and anthracene. While azulene and anthanthrene exhibit a medium conductance as T(E) = 1, and tetracene and dibenzocoronene possess a high conductance with T(E) = 2. Low, medium and high values were elucidated according to the energy gap E g and E g gaps are strongly dependent on the NAR in the PAH derivatives. This study also suggests that any PAH molecules are a conductor if E g < 0.20 eV. A linear relationship between the conductance and NAR (G ∝ NAR) was found and conductance follows the order G (benzene, 1 NAR) < G (anthanthrene, 4 NAR) < G (dibenzocoronene, 9 NAR). The proposed study suggests a relevant step towards the practical application of molecular electronics and future device application

Structural and Optical Characterization of g-C₃N₄ Nanosheet Integrated PVC/PVP Polymer Nanocomposites

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

New Hybrid PVC/PVP Polymer Blend Modified with Er2O3 Nanoparticles for Optoelectronic Applications

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 (Eopt) 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

Synthesis of Sulfur@g-C₃N₄ and CuS@g-C₃N₄ Catalysts for Hydrogen Production from Sodium Borohydride

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

Structure–Property Relationships in PVDF/SrTiO3/CNT Nanocomposites for Optoelectronic and Solar Cell Applications

The optical properties of polyvinylidene fluoride (PVDF) polymer nanocomposite films incorporating SrTiO3/carbon nanotubes (CNTs) as nanofillers are investigated. PVDF/SrTiO3/CNTs films were prepared by the solution casting technique. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses confirmed the incorporation of SrTiO3/CNTs into the PVDF matrix. The addition of nanofillers influenced the crystalline structure, morphology, and optical properties of the films. SEM images showed spherulite morphology, which is a spherical aggregate of crystalline polymer chains. The addition of a SrTiO3/CNTs nanofiller modified the polymer’s electronic structure, causing a variation in the energy gap. The addition of SrTiO3/CNTs at 0.1 wt% increased the band gap, refractive index, and nonlinear optical properties of the PVDF films. These improvements indicate the potential of these nanocomposite films in optoelectronic applications such as solar cells, image sensors, and organic light-emitting diodes

Synthesis of CaCO₃/Cu₂O/GO Nanocomposite Catalysts for Hydrogen Production from NaBH₄ Methanolysis

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

Processing of new efficient Cr1-xNaxO3 catalysts for sodium borohydride methanolysis

This study reports the development of a novel Cr1-xNaxO3 catalyst using a simple cost-effective method for hydrogen production from NaBH4 methanolysis. The properties of the nanocomposites were investigated by employing XRD, FTIR, SEM and XPS characterization techniques. The XRD diffraction peaks confirmed the rhombohedral crystal structure of Cr1.xNaxO3 nanoparticles. The average crystal size of these nanoparticles was found to be ranging from 25.0 to 20 nm. FTIR analysis showed the characteristic absorption bands of Cr1.xNaxO3 nanoparticles. The SEM images of Cr2O3 and Cr1.7Na0.3O3 demonstrated that the nanoparticles are irregular in shape, while Cr1.4Na0.6O3 has a porous surface texture. XPS spectra of Cr2O3, Cr1.7Na0.3O3 and Cr1.4Na0.6O3 confirmed the presence of chromium, oxygen, and sodium in the samples. The optical band gaps of Cr2O3 Cr1.7Na0.3O3 and Cr1.4Na0.6O3 nanoparticles were approximately 3.28 eV, 1.61 and 0.81 eV, respectively. Cr1.4Na0.6O3 exhibited the most significant level of activity in terms of hydrogen production of 19144 mL/g.min

Engineering of the crystalline state towards a defective state of CeCoO3 perovskite for the OER process in alkaline medium

Perovskite oxides act as an efficient electrocatalyst, but their limited active surface area has made it challenging to enhance their electrocatalytic activity. Thus, researchers found that changing the crystalline surface to an amorphous surface having oxygen vacancy can create an enriched active zone. In this research, we adopt a top-down approach for the amorphization of the crystalline CeCoO3 nanostructure that creates crystal defects, producing materials with a higher specific surface area, potential electrocatalysis for oxygen evolution reaction (OER) and greater stability. The calculated overpotential (η) and Tafel slope for defective CoCO3 (D-CCO3) is 265 and 35.95 mV dec−1 very low as compared to the crystalline CoCO3 (C-CCO3, 384 and 76.11 mV dec−1). The electrochemical analysis also suggests that the defective CoCO3 (D-CCO) exhibited the 33.96 mF and ECSA of 849 cm2. The current research enables a valuable approach for improving and changing the material properties and electrochemical efficiency of nanoscale perovskite oxide electrocatalysts attributed to crystal defects and nitrogen doping. However, further modifications to the D-CCO structure in the near future may be employed to address other environmental challenges