Sol-gel Technique Research Articles

Structural, magnetic and electrical studies on nickel doped copper ferrite synthesized using sol-gel method

Nickel doped copper ferrite nanoparticles NixCu1-xFe2O4(x = 0.1, 0.3, 0.5, 0.7, and 0.9) have been prepared through well known sol-gel technique. Numerous analytical methods, including the Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and powder X-ray diffractometer (XRD), were used to analyze the synthesized materials. Synthesized sample XRD patterns reveal the single phase development of the spinel crystalline structure in the absence of any contaminant. The concentration of Ni ions rises with a corresponding decrease in crystallite size. Scanning electron microscopy (SEM) was also used to assess the microstructure. By using UV–Visible spectrometer an optical absorbance and through FTIR, two of ferrite's distinctive bands were verified. The M-H loops show that when the concentration of nickel ions increases, saturation magnetization varies. The Cyclic-Voltameter was used to perform the ionic electrochemical analysis. The NixCu1-xFe2O4 nanopowder's enhanced magnetic characteristics suggest that these substances would make good candidates for magnetic catalysts.

Designing Tb-doped Mn-Ni-Cu ferrite meta-absorbers for a broad frequency range: Magnetodielectric, physical, reflection loss, and absorptivity characteristics

Developing meta-absorbers with exceptional EM wave absorption, shielding capacity, and superior dissipation performance remains worthwhile in the gigahertz (GHz) range. Electromagnetic pollution has a detrimental impact on the health of living organisms due to the emergence of high-frequency waves from communication devices. The challenges were addressed by preparing, designing, and simulating ferrite-based meta-absorbers. The nanoferrites of Tb-doped Mn-Ni-Cu (Mn0.2Ni0.3Cu0.5TbxFe2-xO4) with different levels of Tb (x = 0.00, 0.025, 0.05, 0.075) were prepared utilizing the sol-gel auto combustion technique. The phase, structural, elastic, and magnetic features of the Tb-doped Mn-Ni-Cu ferrites were examined using XRD, FESEM, FTIR, and VSM techniques, respectively. The MAUD software was utilized to obtain refinement and precise structural characteristics. The force constant, phase, and elastic properties were also assessed. The magnetization and coercivity exhibited a reduction. An assessment was conducted on the performance of field switching and high-frequency response. At high frequencies, the dielectric characteristics, such as complex permeability and permittivity, exhibit greater values, while losses diminish. At a frequency of 4.6 GHz, a reflection loss (RL) of −54.21 dB was measured for x = 0.05, whereas a reflection loss of −54.03 dB was measured for x = 0.075. The meta-absorbers of Tb-doped Mn-Ni-Cu ferrites were designed and simulated. The absorptivity of the Tb-doped Mn-Ni-Cu ferrite substrate material is illustrated. The meta-absorber exhibited three distinct absorption peaks at frequencies of 1.5, 2.5, and 4.5–6 GHz, respectively. The absorptivity of the material likewise rises with an increase in the incidence angle; the material's absorptivity also increases. The TM mode exhibited the highest values at an angle of 60 degrees, while the TE mode displayed the highest values at an angle of 0 degrees. Tb-doped Mn-Ni-Cu ferrites are effective for electromagnetic interference (EMI), multilayer ceramic integrated circuits (MLCIs), shielding, and absorbing high-frequency signals in 5 G applications.

High temperature photoluminescence dependence and energy migration of Tb3+-Incorporated K3Y(BO2)6 phosphors

This study investigates the structural and photoluminescence (PL) characteristics of Tb3+-incorporated K3Y(BO2)6 (KYBO) phosphors synthesized via a microwave-assisted sol-gel technique. X-ray diffraction (XRD) and Rietveld refinement confirmed the formation of a pure hexagonal phase, with lattice expansion due to Tb³⁺ doping. PL studies revealed strong green emissions centered at 541 nm, attributed to the ⁵D₄ → ⁷F₅ transitions of Tb³⁺ ions, with the highest intensity observed at 5 wt% Tb³⁺. A decrease in emission was observed at higher concentrations due to concentration quenching. Temperature-dependent PL measurements revealed reverse thermal quenching enhancing PL intensity. Chromaticity analysis based on CIE 1931 coordinates showed stable green emission across all concentrations, with a maximum color purity of 89.74% observed for the KYBO:3 wt% Tb³⁺ sample. The results, along with reverse thermal quenching behavior observed between 470K and 550K, suggest that these phosphors exhibit excellent potential for lighting and display technologies.

Enhancing Efficiency of Dye-Sensitized Solar Cell using Mn or Ce Doped and Co-doped ZnO Photoanodes with Lawsonia Inermis Natural Dye

Abstract In the present research paper, Mn (transition metal) and Ce (rare earth metal) doped and co-doped ZnO nanoparticles were synthesized using a cost-effective sol-gel technique. As synthesized samples were characterized using X-ray diffraction and field emission scanning electron microscope to examine the structure and morphology respectively. The optical properties were examined by UV-Visible and photoluminescence spectroscopic techniques. The synthesized samples were used as photoanode for the fabrication of dye-sensitized solar cell (DSSC). The utilization of a photoanode, containing Mn and Ce doped and co-doped in ZnO, in DSSC leads to a significant enhancement in photovoltaic conversion efficiency with natural dye lawsonia inermis. Different combinations of Mn or Ce doped and co-doped ZnO nanoparticles were used for testing their effectiveness as photoanode in DSSC. It was observed that the efficiency for Mn and Ce co-doped ZnO photoanode-based DSSC was found to be 0.2118%, which is approximately a 750% increase as compared to bare ZnO photoanode based DSSC. The enhancement in the efficiency of DSSCs was due to the formation of a blocking layer by Mn ions which helps to stop the flow of electrons backward and the broadening of the spectrum region with the help of Ce ions using up/down conversion process also helps to achieve higher efficiency. This enhancement in the efficiency of DSSC may be attributed to the synergic effect of Mn and Ce.

MgFeO3 perovskite nanostructures: A New Frontier in photoelectrochemical water splitting

The process of transforming solar power into hydrogen fuel through photoelectrochemical water splitting is a highly viable strategy for producing hydrogen in an environmentally friendly and sustainable manner, offering a long-term solution to the worldwide energy crisis. Therefore, the need for high-performance photoelectrodes is critical for optimizing the transformation of solar energy into hydrogen fuel. Herein, a simple citrate sol-gel technique was employed to fabricate magnesium iron oxide (MgFeO3) for its potential use in photoelectrochemical water splitting. A detailed analysis was undertaken using techniques such as XRD, FESEM, XPS, PL, EDX, and UV–Vis spectrophotometry to uncover the fundamental physicochemical and optoelectronic aspects of the MgFeO3 perovskite material. The MgFeO3 photoelectrode manifests superior PEC characteristics as evidenced by the optimal photocurrent density of 4.5 mA cm−2 achieved at a potential of 1.2 V vs. RHE, and a commendable solar-to-hydrogen conversion efficiency of 0.97%. EIS studies provided evidence of improved charge transfer kinetics and decreased recombination rates in the MgFeO3 photoelectrode. In addition, extended reliability evaluations utilizing chronoamperometry verified consistent operation for 10 h at a photocurrent density of 3.5 mA cm−2, demonstrating the long-term durability of MgFeO3 in PEC water splitting. These results emphasize the considerable promise of MgFeO3 perovskite as a proficient and robust photoelectrode substance for PEC water-splitting applications.

Oxidative Desulfurization of Kerosene in Batch Reactor using Magnetite Mesoporous Silica Composite Zeolite Catalyst

The petroleum refining sector has increasingly prioritized the creation of clean fuel as a crucial priority. The objective of this project is to generate environmentally friendly fuel through the use of a straightforward and uncomplicated method. Using a novel synthetic nano-catalyst, batch oxidative desulfurization (ODS) eliminates sulfur compounds in Kerosene. The new Catalyst's silica nano-particle support is initially manufactured utilizing the sol-gel technique. Subsequently, the support is employed to fabricate a synthetic composite nano-catalyst composed of ferric oxide, utilizing the techniques devised for extracting a novel synthetic handcrafted (Fe2O3/composite support) Nano-catalyst. The composite supports used for the robust studies on the desulfurization process contain different levels of HY-zeolite (100 percent Nano silica). These levels include 10% HY-zeolite + 90% Nano silica, 20% HY-zeolite + 80% Nano silica, and 30% HY-zeolite + 70% Nano silica. The supports and manufactured Catalyst underwent characterization tests, including SEM, XRD, XRF, TGA, FTIR, BET, and particle size distribution. The tests showed an ideal distribution of the active metal (Fe), different surface structures, and a high active metal dispersion were achieved. The prominent locations are identified as limited in number, and the catalysts exhibit metal-support solid interaction. The existing Catalyst's performance was evaluated using a batch reactor. The assessment involved testing the Catalyst at different reaction temperatures (303 to 393 K) and batch times (30 to 120 minutes) while varying HY-zeolite quantities in the composite supports.

Repairment of carbon steel oxide scale using Ce³⁺ and Ni²⁺ doped sol-gel technique

Corrosion of carbon steel rebars in concrete structures significantly compromises their safety, reliability, and environmental performance. This work focuses on enhancing rebar corrosion resistance by repairing the defects of oxide scale. Here, sol-gel was employed as a carrier, by which Ce3+ and Ni2+ were transferred to the oxide scale defects based on the isoelectric point theory, and deposited at these defects with the pH variation as temperature. The repaired oxide scale showed enhanced uniform elemental distribution and improved electrochemical properties, maintaining integrity even under prolonged exposure to Cl−-rich environments. Notably, the impedance modulus at 0.01 Hz (|Z | 0.01Hz) of treated samples was six times higher than untreated ones, indicating superior performance against high electric fields. This strategy shows great potential for enhancing the durability of concrete structures.

Comparative study of the structural, optical, and electrochemical properties of γ-Ga2O3 synthesized by microwave hydrothermal and sol–gel techniques

Comparative study of the structural, optical, and electrochemical properties of γ-Ga2O3 synthesized by microwave hydrothermal and sol–gel techniques

Structural Study on the Novel Plasmonic Optical Materials with Copper Selenide Nanoparticles

Background: Semiconductor-doped materials have been treated actively throughout the last decades and continue to be of great interest because of the challenges of the features due to various nanosize effects. Among other semiconductors, copper chalcogenides demonstrate the interesting plasmonic properties in line with quantum confinement effects provided by the size factor. Objective: This study aims to study the structural and optical features of the sol-gel-derived silica glasses with copper selenide nanoparticles, demonstrating the appearance of the plasmonic light absorption in the near IR range. Method: The samples under study were fabricated through an original sol-gel technique, which realized the simultaneous synthesis of copper selenide and sintering of mesoporous silica. The copper selenide glasses were characterized with X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and optical absorption spectroscopy. Results: Formation of nanocrystalline Cu2-xSe particles of the size range from 10 nm through 100-150 nm is established with XRD and TEM techniques. The principal optical properties are presented by the featured absorption in the visible and near-IR ranges. Eg was evaluated for the direct transitions in the range of 2.10-2.36 eV. The plasmonic resonance in the nanoparticles due to increased carrier concentration originated by intrinsic deficiency of Cu2-xSe nanoparticles with variable stoichiometry. Its energy can be controlled by the Cu/Se ratio in the synthesis procedure. Conclusion: The silica sol-gel glasses with copper selenide nanoparticles were fabricated and characterized by XRD and TEM methods, and their optical absorbance spectra were investigated. The principal optical properties are presented by the featured absorption in the visible and near-IR ranges: the steplike proper absorption of the semiconductor particles characterized by Eg and the intense near-IR band is associated with the localized plasmonic resonance in the nanoparticles due to increased carrier concentration.

Electrospun Mn1-xCoxFe2O4 (x=0–0.7) nanofibers for supercapacitors and oxygen evolution reaction

Cobalt manganese ferrite nanofibers (Mn1-xCoxFe2O4; x = 0, 0.3, 0.5, 0.7), were synthesized using sol-gel electrospinning technique. The impact of cobalt incorporation on physical and electrochemical properties of manganese ferrite nanofibers was investigated. The XRD peaks confirmed the formation of a cubic spinel phase and lattice parameter decreased gradually with increasing cobalt concentration. SEM analysis revealed the nanofibers with diameters in the range of 30–60 nm. VSM analysis showed that magnetic parameters such as coercivity, and saturation magnetization were enhanced by cobalt substitution and the sample Mn0.3Co0.7Fe2O4 showed the highest saturation magnetization and coercivity. DRS analysis exhibited that the incorporation of cobalt in the manganese ferrite reduced the band gap energy. The supercapacitive performance of Mn1-xCoxFe2O4 electrodes was investigated using CV, GCD and EIS in 3 M KOH electrolyte solution. The highest specific capacitance (453 F g−1) was obtained with long cycling stability (94.6 % retention after 4000th cycles) for Mn0.7Co0.3Fe2O4. Furthermore, an asymmetric supercapacitor (ASC) was made with reduced graphene oxide (rGO) and Mn0.7Co0.3Fe2O4 as anode and cathode electrodes, respectively. The Mn–CoFe2O4//rGO ASC revealed an impressive energy density of 50.2 Wh kg−1 at a power density of 750 W kg−1. The electrocatalytic oxygen evolution reaction (OER) performance of the Mn0.7Co0.3Fe2O4 and MnFe2O4 catalysts were also investigated in 1 M KOH alkaline electrolyte. Experiments demonstrated that the Mn0.7Co0.3Fe2O4 nanofiber catalyst had a lower overpotential (201 mV) at 10 mA cm−2, a small Tafel slope (106 mV dec−1), a larger ECSA (176 cm2), a greater TOF (7.68 × 10−4 s−1), and better long-term durability (96.3 % for 12 h) than MnFe2O4 for OER. This highlights the potential of the synthesized Mn0.7Co0.3Fe2O4 electrode for supercapacitor and oxygen evolution reaction.

Structural, Magnetocaloric Effect and Critical Phenomena Studies of La0.8Na0.2Mn0.94Bi0.06O3 Synthesized by Sol–gel Technique

Structural, Magnetocaloric Effect and Critical Phenomena Studies of La0.8Na0.2Mn0.94Bi0.06O3 Synthesized by Sol–gel Technique

Tailoring molecularly imprinted polymer on titanium-multiwalled carbon nanotube functionalized gold electrode for enhanced chlorophyll determination in microalgae health assessment.

A unique method for determining chlorophyll content in microalgae isdevised employing a gold interdigitated electrode (G-IDE) with a 10-µm gap, augmented by a nano-molecularly imprinted polymer (nano-MIP) and a titanium dioxide/multiwalled carbon nanotube (TiO2/MWCNT) nanocomposite. The nano-MIP, produced using chlorophyll template voids, successfully trapped chlorophyll, while the TiO2/MWCNT nanocomposite, synthesized by the sol-gel technique, exhibited a consistent distribution and anatase crystalline structure. The rebinding of procured chlorophyll powder, which was used as a template for nano-MIP synthesis, was identified with a high determination coefficient (R2 = 0.9857). By combining the TiO2/MWCNT nanocomposite with nano-MIP, the G-IDE sensing method achieved a slightly betterR2 value of 0.9892 for detecting chlorophyll in microalgae. The presented G-IDE sensor showed a significant threefold enhancement in chlorophyll detection compared withcommercially available chlorophyll powder. It had a detection limit of 0.917mL(v/v) and a linear range that spanned from10-6to 1mL. The effectiveness of the sensor in detecting chlorophyll in microalgae was confirmed through validation of its repeatability and reusability.

Influence of local structure and metal-oxygen hybridization on the electrical and magnetic properties of alkaline earth metal (Mg2+, Ca2+, Sr2+) substituted LaFeO3 ceramics

Pristine and alkaline-earth metal-substituted LaFeO3 (La1−xAxFeO3−δ; x = 0 and 0.2; A = Mg2+, Ca2+, and Sr2+) sintered ceramics are prepared from nanoparticles synthesized via a low-temperature citrate sol–gel technique. X-ray diffraction studies confirm the formation of a phase-pure LaFeO3 structure without any secondary phases for all the La1−xAxFeO3−δ compositions. LaFeO3 and La0.8Mg0.2FeO3−δ ceramics show Raman active modes related to La vibration, oxygen octahedral tilting, bending, and stretching. The optical bandgap is estimated to be 2.34 eV for pure LaFeO3 and reduces to 2.23 eV for La0.8Mg0.2FeO3−δ ceramics. On the contrary, La0.8Ca0.2FeO3−δ and La0.8Sr0.2FeO3−δ ceramics show no features in Raman spectra, consistent with the observation of metallic nature and diffuse band edge without any indication of sharp band edge noted. X-ray absorption spectroscopy (XAS) studies on La-L3 and Fe-K-edges confirm the oxidation states of La3+ and Fe3+ in all these ceramics. Local structural distortions and formation of oxygen vacancies in La0.8A0.2FeO3−δ (A = Mg2+, Ca2+, and Sr2+) ceramics are discerned from XAS structure analysis compared to the pristine LaFeO3 ceramics. Magnetic measurements of La1−xAxFeO3−δ reveal weak ferromagnetic nature except for La0.8Mg0.2FeO3−δ, which shows a large magnetization of 4.6 (6.7) emu/g at 300 (5) K. The ferromagnetic behavior of La0.8Mg0.2FeO3−δ ceramics seems to originate from the modification of hybridization between Fe(3d)–O(2p), La(5d)–O(2p), and Fe(4sp)–O(2p) orbitals. An anomalous magnetic transition observed only in zero-field-cooled curves at 88 K in La0.8Ca0.2FeO3−δ and La0.8Sr0.2FeO3−δ ceramics is correlated to the formation of new electronic states containing O 2p character as discerned from pre-peak O-K-edge.

CHEMICAL MODIFICATION AND BIOLOGICAL ACTIVITY OF ALGINATE-BASED HYDROGELS

In recent years, the problem of wound infection has risen dramatically. Infectious complications of surgical wounds have increased significantly, often leading to severe sepsis. Gram-negative bacteria and microorganisms, which are immune to virtually all currently available antimicrobials, are the main culprits. In this regard, the development and implementation of innovative drugs and wound dressings, purulent and chronic wound treatment methods is an urgent problem of many domestic and foreign researchers. Brown algae are extracted using an alkaline solution to produce the ionic polysaccharide sodium alginate. It still holds one of the top positions among water-soluble polymers of natural origin as a result of various highly useful practical characteristics. Based on alginate hydrogels, it is possible to create new materials for biotechnological, pharmaceutical and medical purposes, as they have high moisture retention capacity, non-toxicity and self-decomposing ability. After reviewing the literature, we concluded that cefepime is a new antibiotic researched for wound dressing using IV generation cephalosporins as an antibacterial agent. It is highly resistant to hydrolysis by most beta-lactamases and quickly penetrates the cells of gram-negative bacteria. Inside the bacterial cell, it targets penicillin-binding proteins. To obtain new derivatives of sodium alginate with special properties, a chemical method, in particular, thiolene reactions, was used. It should be noted that click chemistry refers to a set of chemical reactions for the rapid and reliable synthesis of compounds by the uniform addition of individual components. Thiolene reactions offer significant advantages, includingversatile reaction conditions (including radical reactions and catalytic processes) and the ability to use a wide range of substrates with different unsaturated bonds such as acrylates, methacrylates and ethers. To monitor the rate and efficiency of UV activation, we used a sol-gel assay technique that allowed us to quantify insoluble (spatially cross-linked) and soluble polymers. After UV activation, samples with different ratios of thiol derivative (S-H bond) showed low viscosity, indicating the predominant degradation of polymer molecules in these systems. Since alginate-polymer derivatives primarily exhibit deconstructive behavior, the dominant process in alginate molecules is the breaking of bonds rather than their formation. The size of the gel fraction reflects the efficiency of polymer cross-linking, which in turn affects the efficiency of immobilization of the drug in the hydrogel matrix and its release rate. This study presents an experimental characterization of photocrosslinked hydrogels aimed at evaluating and elucidating the physicochemical and biological properties of the antibiotic cefepime in an alginate polymer. The obtained kinetic parameters of the swelling-dissolving process show that the synthesized alginate hydrogel is capable of providing a diffused and prolonged release of drugs. In addition, the synthesized hydrogel effectively delivers cefepime to the tested bacterial strains, showing high antibacterial activity without toxicity. However, further in vivo studies are needed to evaluate the fate and toxicity of the alginate-based hydrogel before definitive conclusions can be drawn regarding the usefulness of the synthesized drugs. These preliminary results can be the basis for the development of medical products.

The effect of seed layer cycles on the structural, optical, and morphological properties of ZnO nanorods.

In this study, ZnO seed layers with different cycles were formed on glass substrates by the sol-gel technique, and ZnO nanorods were grown on them by the hydrothermal method. Morphology and the structural characterization of the seed films and the ZnO nanorods are carried out by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction techniques. In addition, to investigate the effect of seed layer deposition cycles on the optical properties of the ZnO nanorod arrays, UV/visible spectrophotometer and photoluminescence (PL) measurements were performed. The changes in structural and optical parameters such as dislocation density, strain, crystallite size, and optical band gap values on each seed layer deposition cycle were examined. The highest optical band gap and crystallite size were obtained for ZnO nanorods with 4 cycles seed layer as 3.22 eV and 63.6 nm, respectively. Also, in the PL spectrum, the largest ratio of UV-emission region to weak-visible emission region was obtained in ZnO nanorods having 4 cycles. In addition, the glucose detection properties of ZnO nanorods having 4 cycles were investigated using the PL measurements and it was found that UV-emission peak intensity of ZnO nanorods decreased as the glucose concentration increased from 8 to 40 mM. The results show that the number of deposition cycles of the seed layer has a strong influence on the orientation, crystal quality, and optical band gap of the growing ZnO nanorods, as well as significantly affecting their morphological properties. RESEARCH HIGHLIGHTS: High quality ZnO nanorods were grown on glass substrates by hydrothermal method. The effect of ZnO seed layer cycles on the structural, optical, and morphological characteristics of ZnO nanorods grown on were examined. It was found that the number of cycles of the seed layer is a critical parameter for growing quality and well-aligned ZnO nanorods.

Influence of Mg2+ substitution on structural, electrical polarization, and magnetic properties of Sr-based R-type hexagonal ferrites

Substitutional effects of Mg2⁺ proceeding the structural, Fourier-transform infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometer characteristics of Sr₁₋ₓMgₓMn₂Fe₄O₁₁ R-type hexaferrite were systematically investigated for different concentrations (x = 0, 0.25, 0.75, 1.0). Sol-gel technique was adopted to fabricate the material. X-ray diffraction analysis confirmed samples exhibit a single-phase structure of MgMn₂Fe₄O₁₁. Lattice parameters (a and c) and V (unit cell volume) decreased with increasing Mg concentration. Also, a rise in dislocation density was observed, while crystallite size varied. FTIR spectra further corroborated the single-phase hexagonal structure of the manufactured samples. The electric polarization (P-E) loops demonstrated that saturation and Pr remanent polarization increased with Mg substitution, while lossy behavior decreased. Magnetic measurements revealed that substituting Mg2⁺ directed toward an initial escalation in saturation magnetization, retentivity, and coercivity, followed by a subsequent decline. Furthermore, VSM analysis indicated that all samples exhibited a combination of ferrimagnetic and paramagnetic behavior.

Hydroentangled waste cotton non-woven based alginate hydrogel wound dressing for high wound exudates

Hydrogels are used in modern wound dressings due to their ability to provide comfort with quick healing. However, poor mechanical properties of hydrogels limit their availability in commercial wound dressings. Nonwovens are highly porous, strong, and flexible structures that can provide support to hydrogels without compromising their properties. In this study, a cost-effective and sustainable hydroentangled nonwoven from industrial cotton waste was prepared and incorporated into alginate hydrogel for wound dressings. The novel composite of hydroentangled cotton nonwoven and alginate hydrogel was synthesized by a simple sol-gel technique. The effect of concentration of alginate hydrogel (0.5 wt%, 1 wt%, 1.5 wt %) and drying temperature (20 °C, 40 °C, 60 °C) of composite was analyzed for high wound exudates. The properties of prepared composite samples were characterized by scanning electron microscopy (SEM), XRD, tensile strength, tear strength, Air permeability, moisture management wound exudate test, and quantitative antimicrobial testing. Moreover, the comfort performance of these samples was evaluated by air permeability and moisture management testing. The properties of developed composites are highly dependent on the concentration of alginate and drying temperature. The results showed that maximum fluid absorbency (%) of 650 was achieved with good comfort properties. This study can help to increase the commercial availability of hydrogel-based wound dressings.

Structural and Luminescent Characteristics of Divalent Europium Activated Barium Aluminate with the Tridymite Structure Synthesized by the Sol-Gel Technique

Abstract: In this study, alkaline earth aluminates were investigated as potential hosts for new blue luminescent materials with nanoparticles. Ba1-xEuxAl2O4 with the stuffed tridymite hexagonal structure was successfully synthesized at 900 °C under controlled sol-gel conditions. Divalent europium was effectively used to activate this host material, producing a brilliant blue-emitting phosphor. Its spectral photoluminescence at 408 nm appears to be in a region close to the laser blue region, with chromaticity coordinate values suitable for the standard blue of the PAL TV system. Keywords: Blue phosphors, BaAl2O4, Divalent Europium (Eu2+), Sol-Gel synthesis, Critical energy transfer.

Investigation of structural, optical, and magnetic properties of NiFe2O4 for efficient photocatalytic degradation of organic pollutants through photo fenton reactions

Nowadays, water pollution generated from textile effluents is one of the major problems for the human race and ecology. Hence, development of sustainable strategies to lower the water pollution level has become a burning need. In this regard, the present study focuses on the preparation of nano catalyst NiFe2O4 to catalyze the chemical reactions on industrial organic dyes for their fast cleansing from water. By sol-gel auto-combustion technique, NiFe2O4 nanoparticles were synthesized and exposed to thermal process at temperatures of 400, 600, and 800 °C. Highly crystalline phase with spinel cubic structured NiFe2O4 was formed with a crystal size of 18.71 nm, which was confirmed by XRD analysis. The FTIR spectra showed two fundamental absorption bands in the range 597.80–412.59 cm−1, which are the characteristics of tetrahedral M − O and octahedral M − O bond in NiFe2O4. The surface morphology of calcined NiFe2O4 was investigated by scanning electron microscope (SEM). The nanoparticle size analyzer exhibited that the synthesized NiFe2O4 nanoparticles had an average particle size of ∼ 291.3 nm. Three stage decomposition patterns were observed for NiFe2O4, which was analyzed by a temperature programmed STA. Zeta potential analyzer showed that the synthesized sample S1 and S2 were stable in the dispersion medium. Also, NiFe2O4 exhibited optical band gap energies for direct band transitions within the visible spectrum measured to be 1.43–1.45 eV, rendering them effective as photocatalysts under sunlight. The samples showed magnetic measurements by VSM with saturation magnetization, coercivity, remnant magnetization value of 66.81 emu/g, 4.13 Oe and 12.94 emu/g, respectively. The synthesized photocatalyst, NiFe2O4, at 400 °C, significantly degraded three toxic organic pollutants—Methylene blue, Rhodamine B, and Congo Red—under visible light through ‘Photo-Fenton’ reaction mechanisms. Among the three dyes, Methylene Blue exhibited the highest degradation percentage with a rate constant of 0.0149 min−1 and followed pseudo-first-order kinetic model.

Investigation of structural, optical, photocatalytic, and antibacterial properties of ZnO doped GO nanoparticles for environment applications.

As a result of their unique and novel properties, nanocomposites have found applications in a wide variety of fields. The purpose of this study is to demonstrate the ability to synthesize nanoparticles consisting of zinc oxide (ZnO) and graphene oxide (GO) via sol-gel techniques. An x-ray diffractometer (XRD) as well as a UV-visible spectrometer were used to determine the crystalline and optical characteristics of the prepared samples. A hexagonal wurtzite crystal structure was observed in both pure ZnO nanoparticles and those that contain GO based on XRD results. It was estimated that the average crystallite size is based on the broadening of x-ray lines. In comparison with pure ZnO, the antimicrobial properties were enhanced when GO was incorporated with ZnO. In addition, experiments on the absorption edge indicated the presence of a red shift as a result of the incorporation of GO. When GO is incorporated in quantitative amounts, the bandgap value of pure ZnO decreased. FTIR spectra exhibit a band of absorption at 486 cm-1, which confirms Zn-O stretching in both samples. SEM images reveal a random pattern of structural features on the surface of the prepared samples. According to the EDX spectrum, pure GO nanoparticles and those doped with ZnO contain 61%-64% zinc and 32%-34% oxygen, respectively. When annealed at a higher temperature, ZnO NPs produced more H2 with a narrower bandgap than before annealing. In addition, methyl blue (MB) was used as an example of an organic compound in order to investigate the potential photocatalytic properties of nanoparticles with ZnO doped GO. In addition to DPPH assays, ZnO nanoparticles and ZnO doped GO nanoparticles were tested for their ability to scavenge free radicals. Comparing ZnO doped GO NPs with pure ZnO, these nanoparticles showed increased antioxidant activity. Based on the increased zone of inhibition observed for pure ZnO and ZnO doped GO (5, 10, 50, and 100 mg/mL), the antibacterial activity of pure ZnO and ZnO doped GO is concentration dependent. A detailed discussion of the results of the study demonstrated that ZnO doped GO and pure ZnO are toxic in different ways depending on how long they survive in degreased Zebrafish embryos and how fast they decompose. RESEARCH HIGHLIGHTS: The scope of the manuscript was under the results of the study confirmed that both nanoparticles exhibited concentration dependent antioxidative activity. Determined that 89% of methyl orange dye can be degraded photocatalytically. ZnO nanoparticles were found to be 74.86% antioxidant at a concentration of 50 g/mL in the present study. At a concentration of 50 g/mL, ZnO doped GO NPs showed 79.1% antioxidant activity. Photocatalytic degradation mechanism scheme is implicit in the photoexcited charge carrier transportation path is observed for all the samples. Survival rate of zebrafish embryos was shown to decrease with increasing concentrations of ZnO and zinc oxide plus GO nanoparticles.