Hydrogen production as a source of clean energy is high in demand nowadays to avoid environmental issues originating from the use of conventional energy sources i.e., fossil fuels. In this work and for the first time, MoO3/S@g-C3N4 nanocomposite is functionalized for hydrogen production. Sulfur@graphitic carbon nitride (S@g-C3N4)-based catalysis is prepared via thermal condensation of thiourea. The MoO3, S@g-C3N4, and MoO3/S@g-C3N4 nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FESEM), STEM, and spectrophotometer. The lattice constant (a = 3.96, b = 13.92 Å) and the volume (203.4 Å3) of MoO3/10%S@g-C3N4 were found to be the highest compared with MoO3, MoO3/20-%S@g-C3N4, and MoO3/30%S@g-C3N4, and that led to highest band gap energy of 4.14 eV. The nanocomposite sample MoO3/10%S@g-C3N4 showed a higher surface area (22 m2/g) and large pore volume (0.11 cm3/g). The average nanocrystal size and microstrain for MoO3/10%S@g-C3N4 were found to be 23 nm and −0.042, respectively. The highest hydrogen production from NaBH4 hydrolysis ~22,340 mL/g·min was obtained from MoO3/10%S@g-C3N4 nanocomposites, while 18,421 mL/g·min was obtained from pure MoO3. Hydrogen production was increased when increasing the masses of MoO3/10%S@g-C3N4.
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 x 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 (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.
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 Edir and indirect Eind 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 (Eg) 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.
Magnetic multilayers with perpendicular anisotropy and an interfacial Dzyaloshinskii-Moriya interaction contain chiral domain walls and skyrmions that are promising for applications. Here we measure the temperature dependence of the Dzyaloshinskii-Moriya interaction (DMI) in Pt/CoFeB/Ir and Pt/CoB/Ir multilayers by means of static domain imaging. First, the temperature dependences of saturation magnetization (MS), exchange stiffness (A) and intrinsic perpendicular anisotropy (Ku) are determined. Then the demagnetized domain pattern in each multilayer is imaged by wide-field Kerr microscopy in the temperature range 9-290 K, and the characteristic domain period at each temperature is determined. We calculate the DMI constant D from an analytical expression for the domain wall energy density that treats the multilayer as a uniform medium. Scaling laws for Ku and D with the magnetization are established from the experiments. While the scaling of Ku is consistent with Callen-Callen theory, we find that the scaling of D is similar to that of A predicted theoretically (∼ 1.8).
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.
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