Turki Alotaibi

This theoretical study investigates the electrical conductance of non-conjugated cyclic molecules featuring three terminal anchoring groups at the single-molecule level. Density Functional Theory (DFT) calculations demonstrate that the conductance of the symmetric and asymmetric cyclic structures C₆C₆, C₆C₈, C₆C₁₀, C₈C₈, C₈C₁₀, and C₁₀C₁₀ (where the numbers indicate the lengths of the upper and lower branches) decreases with increasing molecular length, independent of the anchor group chemistry. Distinct trends are observed across molecular series: the 6-unit branch—defined as molecules containing a common six-carbon saturated segment (e.g., C₄C₆, C₆C₆, C₆C₈, C₆C₁₀)—exhibits a non-conventional pattern, whereas the 8-unit and 10-unit branches display parabolic and conventional length-dependent behavior, respectively. A key finding is that cyclic molecules with identical total CH₂ units exhibit nearly identical conductance values, irrespective of structural symmetry. These theoretical predictions are strongly supported by previously reported scanning tunneling microscopy break-junction measurements, establishing a fundamental structure–property relationship for sigma-conjugated molecular systems. These findings provide critical design principles for developing advanced molecular-scale electronic devices.

This study used the solution casting process to create new composite (PVA/CdNiO) films for applied in energy storage applications. These films were composed of polyvinyl alcohol (PVA) and cadmium nickel oxide nanoparticles (CdNiO). The nanocomposites PVA/CdNiO films were successfully analyzed by the techniques of Raman spectroscopy, scanning electron microscopy (SEM), and Thermogravimetric Analysis (TGA). The SEM images of the composites at various magnifications show clear morphological changes as CdNiO nanoparticles are gradually increased. The thermal stability is modified by the shift in the commencement of thermal deterioration to higher temperatures caused by the addition of CdNiO nanoparticles. The dielectric characteristics of PVA were tested in relation to the concentration of CdNiO at frequencies of 10 Hz and 6 MHz. The conductivity increased from 2.73 × 10 ⁻¹¹ S cm ⁻¹ to 9.68 × 10 ⁻¹¹ S cm ⁻¹ for the composite PVA/CdNiO, whereas the dielectric constant increased from 7.40 to 8.59. According to the data obtained, the dielectric properties were altered, to be able to apply these composites in various dielectric applications.

The urgent demand for efficient CO₂ reduction technologies has driven enormous studies into the enhancement of advanced catalysts. Here, we investigate the electronic properties and CO₂ adsorption properties of Cu_mAg_n bimetallic clusters, particularly Cu₄Ag₁, Cu₁Ag₄, Cu₃Ag₂, and Cu₂Ag₃, using generalized gradient approximation (GGA)/density functional theory (DFT). Our results show that the atomic arrangement within these clusters drastically affects their stability, charge transfer, and catalytic performance. The Cu₄Ag₁ bimetallic cluster emerges as the most stable structure, revealing superior charge transfer and effective chemisorption of CO₂, which promotes effective activation of the CO₂ molecule. In contrast, the Cu₁Ag₄ bimetallic cluster, in spite of comparable adsorption energy, indicates insignificant charge transfer, resulting in less pronounced CO₂ activation. The Cu₃Ag₂ and Cu₂Ag₃ bimetallic clusters also display high adsorption energies with remarkable charge transfer mechanisms, emphasizing the crucial role of metal composition in tuning catalytic characteristics. This thorough examination provides constructive insights into the design of bimetallic clusters for boosted CO₂ reduction. These findings could pave the way for the development of cost-effective and efficient catalysts for industrial CO₂ reduction, contributing to global efforts in carbon management and climate change mitigation.

This study aims to prepare new nanocomposites consisting of Cr₂O₃/CaCO₃ as a catalyst for improved hydrogen production from NaBH₄ methanolysis. The new nanocomposite possesses nanoparticles with the compositional formula Cr_2−xCa_xO₃ (x = 0, 0.3, and 0.6). These samples were prepared using the sol-gel method, which comprises gelatin fuel. The structure of the new composites was studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, environmental scanning electron microscopy (ESEM), and X-ray spectroscopy (XPS). The XRD data showed the rhombohedral crystallinity of the studied samples, and the average crystal size was 25 nm. The FTIR measurements represented the absorption bands of Cr₂O₃ and CaO. The ESEM micrographs of the Cr₂O₃ showed the spherical shape of the Cr₂O₃ nanoparticles. The XPS measurements proved the desired oxidation states of the Cr_2−xCa_xO₃ nanoparticles. The optical band gap of Cr₂O₃ is 3.0 eV, and calcium doping causes a reduction to 2.5 and 1.3 eV at 15.0 and 30.0% doping ratios. The methanolysis of NaBH₄ involved accelerated H₂ production when using Cr_2−xCa_xO₃ as a catalyst. Furthermore, the Cr_1.7Ca_0.3O₃ catalyst had the highest hydrogen generation rate, with a value of 12,750 mL/g/min.

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.

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.

A considerable potential advantage of manufacturing electric and thermoelectric devices using endohedral metallofullerenes (EMFs) is their ability to accommodate metallic moieties inside their cavities. Published experimental and theoretical works have explained the usefulness of this resilience feature for improving the electrical conductance and thermopower. Through thorough theoretical investigations of three EMF complexes employing three different metallic moieties involving Sc₃C₂, Sc₃N, and Er₃N and their configurations on a gold (111) surface, this research demonstrates that the thermoelectric properties of these molecular complexes can be tuned by taking advantage of the charge transfer from metallic moieties to Ih-C₈₀ cages. Mulliken, Hirshfeld, and Voronoi simulations articulate that the charge migrates from metallic moieties to cages; however, the amount of the transferred charge depends on the nature of the moiety within the complex.

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.