Indirect Energy Gap Research Articles

Reinforced PEO/Cs polymers blend with Al2O3/TiO2 hybrid nanofillers: Nanocomposites for optoelectronics and energy storage

This work focuses on the meticulous preparation and characterization of polyethylene oxide (PEO)/chitosan (Cs) polymer blends infused with aluminum oxide nanoparticles (Al2O3 NPs) and sol-gel synthesized titanium oxide nanoparticles (TiO2 NPs). Employing the casting method, the study delves into a comprehensive analysis of the structural, optical, electrical, and dielectric properties exhibited by the resulting PEO/Cs-Al2O3/TiO2 nanocomposites. Structural evaluations utilized transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). UV–Vis spectra showed enhanced optical properties, with the indirect optical energy gap decreasing from 5.23 eV to 5.01 eV for blends with 2.4 wt% Al2O3/TiO2 NPs. The AC conductivity of the polymeric nanocomposites showed enhanced values compared with the pure blend. Additionally, dielectric permittivity and modulus exhibit tunability, presenting advantageous prospects with varying Al2O3/TiO2 NPs concentrations in the PEO/Cs blend. The Nyquist plots reveal distinctive features, including semicircular arcs at the low-frequency part and an inclined spike at the high-frequency part, with decreasing arc radius corresponding to increasing nanofiller contents. These observations are best fitted to two models of equivalent circuits. The engineered PEO/Cs-Al2O3/TiO2 nanocomposite capacitor showed enhanced storage capacity and controlled conductance characteristics. The findings of this study revealed that these nanocomposites hold promise as bandgap tuners, optical sensors, permittivity-tunable nanodielectrics, and novel host matrices for the development of solid polymer flexible electrolytes, thereby contributing to the next generation of energy storage and conversion devices with superior performance.

Grain boundary, electrical transport and thermoelectric properties of the ultra-high rGO amount of C12A7-rGO composites

The Ca12Al14O33 ceramic (C12A7) and reduced graphene oxide (rGO) composite which an ultra-high amount (i.e., 40, 50, 60, and 70 wt%) of rGO (ultra-high amount C12A7/rGO composite) were synthesized by a solid-state reaction process. After the hydraulic press, the heat treatment in the temperature range of 773 K under the argon environment had been performed with the composite pellets for 30 min. XRD results of the C12A7 and all the ultra-high amount C12A7/rGO composites indicated a pure phase of C12A7 ceramic. Raman spectra confirmed the existence of rGO content in all the ultra-high amount C12A7/rGO composites. Raman peaks also suggested reduction of the free O22− and O2− ions from the framework of the ultra-high amount C12A7/rGO composites. SEM image presented the homogeneous grain boundary interface after the heat treatment at 773 K of the C12A7 wrapped by the rGO sheet, the agglomerated rGO sheet, and the rough interface stack of rGO sheets. UV-VIS spectroscopy presented the absorption behavior, direct energy gap, and indirect energy gap modifications of the ultra-high amount C12A7/rGO composites. Electrical conductivity of the ultra-high amount C12A7/rGO composites illustrated larger than 108 times improvement with temperature independence. Range of −5 to −17 μV/K , temperature dependence, and increased with rGO content increasing Seebeck coefficient were reported. Thermal conductivity of the ultra-high amount C12A7/rGO composites was increased with the rGO content increasing. Both the Power factor (PF) and the figure of merit (ZT) of the ultra-high amount C12A7/rGO composites were temperature dependent and were increased with the rGO content increasing, within the range of 0.4 μW/m.K2 of PF and the range of 3x10−4 of ZT, respectively. These experimental results verified grain boundary, modified energy band, electrical transport properties and thermoelectric properties of C12A7/rGO composites loading with ultra-high content rGO

Optical properties of synthesized PVA/Cellulose phosphate composite films doped with Zn2+ ions for optical device applications

In this work, composite films of polyvinyl alcohol/cellulose phosphate doped with Zn2+ (PVA/CP/Zn2+) were prepared through a film casting procedure. The prepared films were analyzed using XRD, FTIR, TGA, and SEM. The XRD revealed a decrease in the semi-crystalline nature as Zn2+ concentrations increased. The TGA showed enhanced thermal stability for the composite films, where the SEM images illustrated the formation of a non-homogeneous surface morphology. The transmittance-absorption spectroscopic measurements showed a noticeable decrease in both the indirect energy gap (Eig) and the direct energy gap (Eg). Eig was decreased from 5.05 to 4.77 eV and Eg decreased from 5.51 eV to 5.12 eV with increasing Zn2+ concentration from zero to 14 wt%. Moreover, the transition strength (Ed), oscillator wavelength (λo), and the excitation energy (Es) were found to increase as Zn2+ content increased. These findings not only shed light on the physicochemical attributes of the prepared films but also emphasize their promising potential utilization in optical components.

Fabricating and examining nanocomposite of P3HT- Graphene- MoS2 by laser ablation method

Abstract This study presents the first successful synthesis of a nanocomposite comprising Poly (3-hexylthiophene) (P3HT), graphene (G), and molybdenum disulfide (MoS2) via laser ablation, using a Q-switch Nd-YAG laser with a repetition rate of 1 (Hz) and different laser pulses of 200, 500, and 800 for both graphene and MoS2, the morphological and optical properties of the samples was thoroughly investigated by various analytical techniques including Transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR), and spectrophotometer UV-Vis. Transmission electron microscopy showed that the graphene and molybdenum nanoparticles were semispherical or ball-shaped, with diameters ranging from 6.7 to 61.7 nm. The UV-Vis findings show that the absorbance and absorption coefficient increase with the number of pulses due to the increased concentration of nanoparticles. The FTIR results confirm strong bonding between the P3HT-G800P/MoS2 800P nanocomposite bonds. The indirect energy gap of the Nanocomposite is estimated to be 1.99 (eV), making it attractive for optoelectronic applications.

A comprehensive study on structural, optical, electrical, and dielectric properties of PVA-PVP/Ag-TiO2 nanocomposites for dielectric capacitor applications

Nanocomposites made from polymers and nanoparticles (NPs) have a wide range of uses. Herein, the polymer nanocomposite electrolyte films were prepared by blending polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) with hybrid NPs of silver (Ag) and titanium dioxide (TiO2). The structural, optical, electrical, and dielectric properties of the resulting PVA-PVP/Ag-TiO2 nanocomposite electrolytes were analyzed. XRD analysis revealed that the PVA-PVP blend had a semicrystalline structure, and the addition of hybrid NPs reduced the crystallinity ratio. FTIR analysis showed that the intensity decreased as the content ratio of hybrid NPs increased. Optical measurements showed that the nanocomposite electrolyte samples' direct and indirect optical energy gap decreased with the increasing content of hybrid NPs. The electrical conductivity also increased with the hybrid NPs' content, likely due to the higher conductivity of the hybrid NPs compared to the polymer blend matrix's electrical conductivity. The dielectric constant (εr) and dielectric loss (εi) increased with the concentration of hybrid NPs at lower frequencies, indicating the polarization effects of space charges. The capacitance–frequency (C–f) and conductance–frequency (G/ω–f) curves of the prepared polymer nanocomposites exhibited a discernible enhancement correlating with the increased content of Ag-TiO2 nanofillers. The impedance spectroscopy data were analyzed using Nyquist plots, which showed a single semicircular arc whose radius of curvature decreased with increasing the hybrid NPs loading, indicating a decrease in the overall impedance of the nanocomposite electrolytes with the mixed NPs loading. The impedance reduction and dielectric feature increase were attributed to the interfacial polarization between the hybrid NPs and the polymeric matrix. These findings suggest that the PVA-PVP/Ag-TiO2 nanocomposite electrolytes could be used for thin-film dielectric capacitor applications.

A systematic study of TMO n (TM = V, Cr, Mn, and Fe; n = 3 and 6) clusters embedded in a PtS2 monolayer.

Doping-based magnetism engineering is an effective approach to synthesize new multifunctional two-dimensional (2D) materials from their non-magnetic counterparts. In this work, doping with TMO n clusters (TM = V, Cr, Mn, and Fe; n = 3 and 6) is proposed to induce feature-rich electronic and magnetic properties in a PtS2 monolayer. The pristine monolayer is a non-magnetic semiconductor with an indirect energy gap of 1.81 (2.67) eV as obtained from PBE(HSE06)-based calculations. PtS3-type multivacancies magnetize significantly the monolayer, inducing the emergence of half-metallicity. In this case, a total magnetic moment of 1.90 μB is obtained and magnetic properties are produced mainly by atoms around the vacancy sites. Meanwhile, the PtS2 monolayer is metallized by creating PtS6-type multivacancies without magnetization. Depending on the type of TMO n cluster, either a feature-rich diluted magnetic semiconductor or half-metallic nature is induced, which is regulated mainly by the incorporated clusters. Except for the FeO6 cluster, TM atoms and O atoms exhibit an antiparallel spin orientation, resulting in total magnetic moments between 1.00 and 4.00 μB. Meanwhile, the parallel spin ordering gives a large total magnetic moment of 5.99 μB for the FeO6-doped monolayer. Furthermore, Bader charge analysis indicates that all the clusters attract charge from the host monolayer that is mainly due to the electronegative O atoms. Our results may introduce cluster doping as an efficient way to create new spintronic 2D materials from a non-magnetic PtS2 monolayer.

Structural and Optoelectronic Properties of Cubic Perovskite Type XAlO3 (X = Gd and Dy) Theoretical Investigation

Abstract In this paper, we have performed a theoretical study using the linear augmented and linearized plane wave method (FP-LAPW) implemented in the Wien2k computational code based on density functional theory (DFT) to determine the structural, electronic and optical properties of GdAlO3 and DyAlO3 perovskites. The exchange and correlation potential are treated by the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE) and modified Becke-Johnson potential (mBJ). The structural properties such as lattice parameter, modulus of compressibility and its derivative are in good agreement with other theoretical results. The electronic properties, such as band structure and density of state revealed an indirect energy gap in the L - xG direction for GdAlO3, with gap values of 2.879 eV (GGA-PBE), 5.006 eV (mBJ) in spin-up and 2.286 eV (mBJ), 2.736 eV (mBJ) in spin-dn.for DyAlO3 perovskite, due to the over lap of the valence and conduction bands at Fermi level, which behaves like a metal oxide. We have also calculated the optical properties of these two compounds, such as dielectric function, refractive index, absorption coefficient and optical conductivity. They indicate that GdAlO3 and DyAlO3 perovskites could be useful for applications in UV photo catalysis.

Role of vacuum annealing on the structural, optical properties and Dc conductivity of titanium (IV) phthalocyanine dichloride thin films

The present work elucidates the significant alterations in several physical characteristics of thermally evaporated TiPcCl2 thin films resulting from vacuum annealing at 373 and 473 K. The structure, surface morphologies, and molecular structure of TiPcCl2 thin films were studied using x-ray Diffraction (XRD), Transmission Electron Microscope (TEM), Field-Emission Scanning Electron Microscope (FESEM), and Fourier Transform Infrared (FT-IR). Results confirmed nanostructure attributes of as-deposited and annealed films, as well as the phase transition in TiPcCl2 was observed during annealing. The optical constants of as-deposited and annealed films in the wavelength range of 200–2500 nm were determined using spectrophotometric techniques. The indirect optical energy gap was observed to diminish with increasing annealing temperature due to enhanced crystallinity of thin films. Using the single oscillator model, the dispersion of the refractive index at normal dispersion was investigated. The third-order nonlinear susceptibility, χ(3), the nonlinear refractive index n2 and the nonlinear absorption coefficient, βc, were calculated and then discussed for both the as-deposited and annealed films. The electrical conductivity of TiPcCl2 exhibited increased as the temperature increased, suggesting its characteristic as a conventional organic semiconductor. The parameters of Mott’s model were obtained and discussed under low-temperature conditions afterward. Conclusions derived from this research indicate that the unique properties of vacuum annealing TiPcCl2 have great promise for future use in optoelectronic systems.

Fabrication, spectroscopic properties, antioxidant and antimicrobial activities of Chitosan-CaLi@Flumox nanocomposites

In the current study, we examined the impact of introducing Flumox into the chitosan/calcium lithium (Chitosan-CaLi) nanocomposite on its spectroscopic, thermal, and antimicrobial characteristics. The formation of the nanocomposites was achieved using the sol–gel method/polymerization, which was chosen for its cost-effectiveness and straightforward processing. The UV–Visible optical analysis shows an absorption peak at 290 nm across all samples. Both direct and indirect energy gap types are available where the indirect event exhibits a higher value than the direct transition. There is a noticeable decrease in both transition energies with the increase in Flumox content. The findings indicated that as the Flumox concentration increased, the Ic50 value also increased, signifying a decrease in antioxidant capacity. The results from the obtained systems revealed that chitosan-CaLiO nanoparticles loaded with Flumox exhibited remarkable antimicrobial activity, particularly against Pseudomonas aeruginosa and Staphylococcus aureus, demonstrating the highest growth inhibition rate. However, in the case of Aspergillus niger and Candida albicans, the antimicrobial activity was comparatively lower.

An efficient GaS/ XTe2 (X=W, Mo) vdW heterstructure photocatalyst for water splitting: The first-principles study

In this paper, the electrical and optical properties of GaS/MoTe2 and GaS/WTe2 van der Waals heterostructure are investigated by first-principles methods, and their properties are modulated by applying biaxial strain and doping. It was revealed that the unstrained GaS/MoTe2 and GaS/WTe2 van der Waals heterostructures is semiconducting with an indirect bandgap of 1.16 eV and 1.28 eV using PBE methods, and the direction of the built-in electric field of the heterojunction is XTe2 pointing to GaS, which is perfect for powerful light absorption. The bandgap widths of the two heterostructure are significantly reduced compared with that of monolayer materials. Besides, the results show that the biaxial strain is an effective tool for adjusting the energy gap where the indirect energy gap under the strain effects ranged within a range of 0.33/0.34 eV at −8% to 0.361/0.464 eV at 6%. At −8% compressive strain, the interfacial charge transfer reaches a maximum for each of the two heterostructure. In addition the absorption coefficients of GaS/MoTe2 and GaS/WTe2 heterostructure increase in the visible and infrared regions and the absorption spectral range is broadened. Therefore, GaS/MoTe2 and GaS/WTe2 vdW heterostructure can be applied in photocatalytic water decomposition and other fields.

Optical Properties of PVA Silicon Carbide Nano Composites Films Synthesized Via Laser Ablation

Background: Enhancing the optical characteristics of nano-silicon carbide and polyvinyl alcohol films is thought to be crucial for obtaining the semiconductor with the lowest energy gap for applications in electrical devices, digital displays, and sensors.
 Materials and Methods: Poly vinyl alcohol and silicon carbide's optical properties were examined. A pulsed laser with a 532 nm wavelength is used to create these nanoparticles into widespread nanoparticles in two environments (water and vinyl alcohol). Polyvinyl alcohol nanocomposite was created by spin coating silicon carbide particles with the weight fractions 0.90%, 0.91%, 0.93%, and 0.95%. Fourier spectroscopy was used to locate the functional groups based. Techniques FESEM were used to analyze the surface composition and nanoparticle dispersion on the membrane-surface of the nanocomposite. using spectroscopy UV-Vis used to record the absorbance spectrum in the range of (200-800) nm for ultraviolet radiation.
 Results: The direct energy gap (5.585, 5.310, 5.480, 4.986, 4.800) eV and the indirect (5.006, 4.880, 4.916, 4.683, 4.490) eV and Urbach energy (2.38, 2.45, 2.94, 2.74, 3.67) eV were calculated.for the samples by ratio, as shown in Table No. 1.
 Conclusion: By investigating the optical characteristics of nanoparticles, such as their extinction and absorption coefficients, direct and indirect optical energy gaps, and Urbach energies .increase in extinction and absorption coefficients Urbach energy when adding nano carbide to polyvinyl alcohol, results show narrowing of the direct and indirect energy gaps. This suggests that the nanocomposite's optical characteristics have improved.

Investigation of linear and non-linear optical features of crystalline and non-crystalline iron oxide thin films for optoelectronic purposes

Spray pyrolysis at various temperatures was employed to produce non-crystalline and crystalline iron oxide (α-Fe2O3) thin films on glass. The amorphous and crystalline characteristics of α-Fe2O3 thin films were affirmed via X-ray diffraction analysis. With low deposition times (5 min) and at various substrate temperatures, iron oxide seems almost in a non-crystalline structure. As for the increase in deposition time (40 min), the crystallinity’s degree was enhanced. According to Tauc’s law, the direct gap energy Ed for both the amorphous and the crystalline phases, were found to be 1.95 and 2.125 eV, respectively. Moreover, the indirect gap energy, Ein = 1.65 and 1.71 eV were obtained for the amorphous phases and the crystalline phases, respectively. The linear and non-linear optical features of amorphous and crystalline structure were meticulously and adaptably detailed. It is observed that the behavior of the refractive index n (λ) and extinction coefficient k (λ) of the crystalline state was lower than that of the amorphous state. The real and imaginary linear dielectric constant and also the thin film quality factor were estimated for both the amorphous and crystalline states as well as the volume and surface energy loss functions for the crystalline and amorphous states. In conclusion, amorphous and crystalline α-Fe2O3 nanocrystalline films improved their optical properties, making them potential candidates for multifunctional applications such as optoelectronics and spintronics electronics devices.

Extraction and studies of optoelectrical parameters of PVC/Zn0.9M0.1S (M: Co, Fe, Mn, V) films

To be used in optoelectronic applications, the nanocomposites films (doped PVC with Zn0.9M0.1S samples: M = Co, Fe, Mn, V) were prepared in this study. Casting and solid-state reaction procedures were employed to prepare PVC/CMC/Zn0.9M0.1S films. Rietveld refinement method and transmission electron microscope technique were used to investigate the structure and microstructure parameters of Zn0.9M0.1S (M: Co, Fe, Mn, V). X-ray diffraction, Fourier transform infrared and scanning electron microscope techniques were used to study the change in the structure, surface morphology and vibrational bands of PVC polymer upon doping with Zn0.9M0.1S. According to the findings, changing the type of the transition metals in Zn0.9M0.1S caused a change in the host polymer's optical characteristics. Depending on the kind of transition metals in Zn0.9M0.1S, the direct and indirect optical energy gaps of PVC/CMC/Zn0.9M0.1S are irregularly reduced. The direct/indirect optical band gaps of PVC dropped from (5.59, 5.22) eV to minimum values of (5.3, 4.27) eV as it was doped with ZnS. As Zn0.9M0.1S was incorporated into the PVC matrix, the linear and nonlinear optical parameters increased. The fluorescence intensity of pristine PVC is very weak, and it enhanced greatly as it doped with Zn0.9M0.1S. The dielectric constant (ε′), dielectric loss factor (ε″), ac conductivity (σac), the real (M′) and imaginary (M″) parts of the electric modulus changed nonmonotonically with the type of metal in Zn0.9M0.1S. Among all polymers, ′, ″ and σac revealed highest values for the PVC/Zn0.9Co0.1S and the lowest ones for PVC/Zn0.9V0.1S.

Sn-Induced Synthesis of Highly Crystalline and Size-Confined Si Nanorods at Moderately High Temperatures Using Hydrogen Silsesquioxane

Size-confined Si nanorods (NRs) have gained notable interest because of their tunable photophysical properties that make them attractive for optoelectronic, charge storage, and sensor technologies. However, established routes for fabrication of Si NRs use well-defined substrates and/or nanoscopic seeds as promoters that cannot be easily removed, hindering the investigation of their true potential and physical properties. Herein, we report a facile, one-step route for the fabrication of Si NRs via thermal disproportionation of hydrogen silsesquioxane (HSQ) in the presence of a molecular tin precursor (SnCl4) at a substantially lower temperature (450 °C) compared to those used in the synthesis of size-confined Si nanocrystals (>1000 °C). The use of these precursors allows the facile isolation of phase-pure Si NRs via HF etching and subsequent surface passivation with 1-dodecene via hydrosilylation. The diameters (7.7–16.5 nm) of the NRs can be controlled by varying the amount of SnCl4 (0.2–3.0%) introduced during the HSQ synthesis. Physical characterization of the NRs suggests that the diamond cubic structure is not affected by SnCl4, HF etching, and hydrosilylation. Surface analysis of NRs indicates the presence of Si0 and Sin+ species, which can be attributed to core Si and surface Si species bonded to dodecane ligands, respectively, and a systematic variation of the Si0:Si–C ratio with the NR diameter. The NRs show strong size confinement effects with solid-state absorption onsets (2.51–2.80 eV) and solution-state (Tauc) indirect energy gaps (2.54–2.70 eV) that can be tuned by varying the diameter (16.5–7.7 nm). Photoluminescence (PL) and time-resolved PL (TRPL) studies reveal size-dependent emission (1.95–2.20 eV) with short, nanosecond lifetimes across the visible spectrum, which trend closely with absorption trends seen in solid-state absorption data. The facile synthesis developed for size-confined Si NRs with high crystallinity and tunable optical properties will promote their application in optoelectronic, charge storage, and sensing studies.

Elastic, anisotropic, lattice dynamics and electronic properties of XNiM and XNi2M (X = Ti, Zr, Hf; M = Sn, Ge, Si): DFT comparison study

The ab-initio calculations were performed using density functional theory (DFT) as implemented in the Quantum ESPRESSO (QE) code. Lattice parameter mismatch was minimal (2.5 % - 3 %) in TiNiSn/TiNi2Sn, ZrNiSn/ZrNi2Sn, and HfNiSn/HfNi2Sn compounds. Half-Heusler compounds had shorter bond lengths and smaller bulk moduli than their full-Heusler counterparts. Directional dependencies of the Young’s and shear moduli were investigated using elastic constants. TiNiGe, HfNiSn, and ZrNiSn had a greater universal anisotropy index among the half-Heusler compounds. Half-Heusler, TiNi2Sn, TiNi2Si, ZrNi2Sn, and HfNi2Sn compounds are reported to be dynamically stable. The electronic structure computations show that TiNiSn, ZrNiSn, and HfNiSn compounds have the least indirect energy gaps of 0.4508 eV, 0.5019 eV, and 0.3847 eV respectively. TiNiSn, ZrNiSn, and HfNiSn compounds are good candidates for minimizing the thermal conductivity of thermoelectric devices. TiNi2Sn, ZrNi2Sn, and HfNi2Sn are good candidates as possible contact electrodes for TiNiSn, ZrNiSn, and HfNiSn.

Electronic Transport via Interstitial States in Mayenite Electride

Earlier theoretical calculations of the Seebeck coefficient of mayenite electride have shown that electrons are the major type of charge carriers, while experimental measurements show that the carriers are holes. We investigated the interplay between the experimentally observed deformation of Ca–Al–O cages in mayenite electride and its transport properties to reveal the reasons for this discrepancy. We found that the deformation of individual cages lifts the degeneracy of the electride subsystem and induces the localization of electrons in these interstices. This leads to significant changes in the band structure near the Fermi level, accompanied by splitting of the electride states into two subsystems separated by an indirect energy gap. As a result, the sign of the Seebeck coefficient changes and becomes positive, indicating that holes are the main type of charge carriers in accordance with the experimental observations. This outcome confirms that the mayenite electride subsystem cannot be considered as a homogeneous gas of free electrons but should be considered as partially localized electrons that can move through the crystal together with local deformations.

Elucidation of the effect of hybrid copper/selenium nanofiller on the optical, thermal, electrical, mechanical properties and antibacterial activity of polyvinyl alcohol/carboxymethyl cellulose blend

AbstractPolymer nanocomposite samples of a polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC) blend doped with copper nanoparticles and selenium nanoparticles (Cu NPs/Se NPs) were prepared by the casting method. X‐ray diffraction analysis (XRD) patterns showed an increase in the degree of amorphous nature of the host polymeric matrix with increasing content of Cu/Se nanoparticles. The addition of 1.60 wt.%, Cu/Se NPs narrowed the indirect optical energy gap value of the nanocomposite from 3.97 to 2.39 eV. In addition, the differential scanning calorimetry (DSC) curve of the pure blend displays the miscibility of the blend components, confirmed by the presence of a single glass transition. Transmission electron microscopy (TEM) micrographs showed that the average sizes of Cu and Se nanoparticles are about 11 and 41 nm, respectively. The maximum values of AC and DC conductivity were 6.76 × 10−6 S.cm−1 and 5.49 × 10−10 for a PVA/CMC film filled with 1.60 wt.% of Cu‐Se NPs. The mechanical properties of the PVA/CMC blend improved after adding the hybrid NPs. Moreover, the antibacterial activity of the prepared samples was increased due to the filling of Cu‐Se nanoparticles to the films. Therefore, these results indicate the multifunctionality of PVA/CMC/Cu‐Se nanocomposite samples for use in electrical energy storage, solid‐polymer electrolytes, and food packaging industry.

Influence of phosphorus-doped bilayer graphene configuration on the oxygen reduction reaction in acidic solution

The challenges posed by global warming and climate change can be solved by utilizing alternative and renewable energy sources to provide efficient and ecofriendly energy for sustainable energy conversion. Fuel cells, especially polymer electrolyte membrane fuel cells (PEMFCs), can convert air pollution via chemical reactions to generate electricity and water and are considered next-generation technologies for the green economy. The oxygen reduction reaction (ORR) at the catalyst layer plays an important role in determining a fuel cell's price and electrochemical performance. Recently, non-platinum-group metals (non-PGMs) have emerged as promising low-cost and high-performance catalysts for PEMFCs. This study investigates the electronic properties and the electrocatalytic activity of a single P-doped monovacancy (PC3-BLG) and divacancy (PC4-BLG) of an AB-bilayer graphene in a sulfuric acid solution. The results show that the PC3-BLG exhibits greater stability and better electrocatalytic activity than the PC4-BLG. For the PC3-BLGs, an indirect energy gap of ∼0.46 eV is predicted, suggesting a transformation from a half-metallic to a small-bandgap semiconductor, whereas the PC4-BLG is predicted to be a p-type semiconductor. An activation energy of 0.54 eV was found for the PC3-BLG, where the rate-limiting step in the ORR is the formation of a second H2O molecule, indicating that phosphorus-doped monovacancy at the hollow site of bilayer graphene (PC3-BLG) is a promising non-PGM alternative to Pt/C catalysts under acidic conditions. These points suggest potential strategies for including carbon-allotrope-based materials in the design of efficient non-PGM catalysts for the ORR.

Study the Effect of Deposition Time on Optical Properties of CdZnS Nanofilms

The optical properties of CdZnS nanofilms are studied in this paper in relation to the deposition time. Deposition times ranged from 15 to 60 minutes for the CdZnS thin films, which had been developed on surface of glassy substrates. The other factors, such as reactant concentration, solution pH, and bath temperature, were held constant throughout the deposition process. The films were annealed at 200 °C for 120 minutes in a thermal furnace after the deposition process. Measurements of absorbance, transmission spectrum, and direct and indirect energy gaps were made using UV-VIS spectrophotometers. Transmittance in the 400-1000 nm range was 70-90 percent for all of the prepared films. With a wavelength of 600 nm and higher, transmittance was around 90%. CdZnS films have bandgap energies ranging from 2.4–2.15 eV for direct transitions and from 2.1–1.97 eV for indirect band gaps.

The optical properties behavior of modify poly(methyl methacrylate) nanocomposite thin films during solar energy absorption

Herein, nanoparticles (Co3O4, Cr2O3, CuO, and TiO2) doped PMMA were fabricated via casting method. The PMMA nanocomposite thin films have been prepared with a fixed concentration of 4 g from PMMA to make PMMA thin films, they were modified with amine cluster. These thin films were doped by a fixed concentration, 0.01 gm, of various nanomaterials (Co3O4, Cr2O3, CuO, and TiO2) to make the nanocomposite thin films of PMMA. The thin film samples were examined by UV–Visible wavelength between (250–1350 nm). The optical properties, optoelectronic features, and oscillator strength were investigated. The reflectance and transmittance values were decreased for all the nanocomposite thin films of PMMA. The absorption coefficient ranged between (99.8–92.0%) for all samples. The direct energy gap decreased from 4.65 eV for the blank PMMA and it with Co3O4 to 2.10 eV, also, for the indirect energy gap decreased from 4.2 eV for the blank PMMA and it with Co3O4 to 2.8 eV due to the modified and doped PMMA. The optoelectronic features such as dielectric of high frequency and effective mass increased, oscillator strength decreased, dispersion energy and effective energy of single oscillator increased in comparison to blank PMMA. The oscillator strength for these thin films were increased also. These nanocomposite thin films are suitable to enhance the photostability performance from UV light and drastic weather are needed especially for underwater, aerospace, and applications for air transport, in addition, fabricated shields from UV energy, light-emitting diodes, lasers sensors, memory devices, harvesting light, and converting-light devices.