Journal of Sol-Gel Science and Technology最新文献

This study aims to fabricate undoped and 6% Bi-doped MAPbI₂Br perovskite layers using the spin coating method and study their structural, morphological, and photovoltaic properties. The cubic structure of MAPbI₂Br was verified by X-ray diffraction, with relatively large grains being observed in SEM micrographs. Compared to its pristine counterpart, the 6% Bi-doped MAPbI₂Br layer shows an improved refractive index and a smaller bandgap, according to UV-visible spectroscopy. This work presents a dual-layer electron transport layer (ETL) design made of TiO₂ and Al-SnO₂ that is especially suited for PSCs containing MAPbI₂Br as the hole transport layer (HTL). This arrangement marks a major milestone for perovskite solar cells (PSCs) with Bi-MAPbI₂Br as absorber and an inorganic ETL, achieving an open-circuit voltage of 1.07 V and a power conversion efficiency of 10.39%. The conduction band alignment of MAPbI₂Br and Al-SnO₂ promotes effective electron transport, which leads to a reduction of recombination losses and thus enhances the power conversion efficiency of the solar cell.

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This investigation employed the sol-gel technique to prepare Co²⁺-Cu²⁺ doped M-type barium-strontium hexagonal ferrite. X-ray diffraction (XRD), along with field emission scanning electron microscopy (FESEM), have been utilized to investigate the crystal structure and morphology of the grains, respectively. An impedance analyzer was utilized to evaluate electrical parameters at room temperature. The formation of an M-type hexagonal crystal *-structure was confirmed by the X-ray diffraction profile, along with minor traces of hematite. In SEM analysis, it was seen that as doping levels are increased, the small size of each grain becomes prominent in the grain clusters, giving rise to a prominent rice-grain shape. The dielectric loss tangent is increased, and the dielectric constant is decreased as doping levels rise. The interplay between grain boundaries and grains has a notable impact on relaxation characteristics across various doping concentrations, leading to the presence of both strong and partial relaxations in low and high-frequency domains. This behavior contributes to the development of either depressed or expanded semicircles influenced by the interactions at grain and grain boundary levels. Analysis of the Cole-Cole plots for electric modulus indicated significant conductivity relaxation. Different relaxation periods were observed in correlation with the conductivity relaxation, and spectra of the electric modulus confirmed the material’s non-Debye behavior.

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The pristine anatase titanium dioxide (TiO₂) and transition metal (i.e. Cu and Co) co–doped anatase titanium dioxide nanoparticles (Ti_0.988Cu_0.002Co_0.01O₂) were synthesized using sol–gel auto–combustion technique. Structural, optical and dielectric properties have been studied to understand the effect of dopants across TiO₂ lattice. X–ray diffraction (XRD) and Rietveld refinements confirm the formation of tetragonal structure having I4₁/amd space group, and crystallite size for co–doped TiO₂ nanoparticles falls ~12.68 nm which has been further verified by Raman spectroscopy. UV visible spectroscopy was performed to estimate the band gap energy that gets reduced from ~3.2 eV for TiO₂ to ~1.7 eV for co–doped TiO₂ nanoparticles. Dielectric constant, dielectric loss and ac conductivity for co–doped TiO₂ sample are explained in terms of crystallite size, related grain boundaries and their nature.

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In this study, wet chemical methods are employed to synthesize zinc oxide nanocomposites in combination with nickel-iron layered double hydroxides (ZnO@NiFe-LDH). A structural analysis confirmed that ZnO@NiFe-LDH nanocomposites possess tunable surface properties and have been successfully formed. The photocatalytic degradation of methylene blue in aqueous solution was demonstrated under the influence of natural sunlight. A number of photocatalytic parameters were observed, including the initial dye concentration, the pH of the dye solution, anionic effects, and cycling stability. During the deposition of ZnO, 0.75 g of NiFe-LDH was added, resulting in ZnO@NiFe-LDH/3 with the lowest optical band gap of 2.68 eV. A degradation efficiency of 99% was observed for ZnO@NiFe-LDH/3. In the repeatable five degradation cycles of the ZnO@NiFe-LDH nanocomposite, the degradation kinetics followed pseudo-first order, with a slight decrease in degradation efficiency from 99 to 88%. In order to validate the effects of real wastewater environments on the degradation performance of the ZnO@NiFe-LDH nanocomposite, a study was conducted with anionic compounds, such as chloride, sulfate, and nitrate. Results showed that anionic compounds such as chloride, sulfate, and nitrate had a negligible effect on degradation. It is evident from the results of this study that the photocatalyst protocol may have great potential for wastewater treatment.

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Left hand side: This work illustrates the synthesis of ZnO@NiFe-LDH composites. Right hand side: The efficient degradation of methylene blue using different catalyst dose under the illumination of natural sunlight.

This study investigates the physicochemical properties and antibacterial activity of hydroxyapatite (HA) nanoparticles synthesized using Basella alba mucilage (BAM) as a natural template and coated with Stephania pierrei (S. pierrei) extract. HA composites were prepared via the sol-gel method with varying BAM concentrations (0–25 wt%) to optimize material properties. S. pierrei tuber and leaf extracts were then incorporated, forming functionalized S. pierrei/BAM-HA materials. Characterization via X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and N₂ adsorption/desorption confirmed the formation of biphasic calcium phosphate structures with enhanced surface area and reduced particle sizes. The 5 wt% BAM composite exhibited the highest surface area (17.59 m²/g) and smallest particle size (6.57 nm). Antibacterial activity was evaluated against Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus aureus, and Bacillus subtilis using the agar well diffusion method. The S. pierrei/BAM-HA composites showed selective antibacterial effects, particularly against Pseudomonas aeruginosa and Bacillus cereus. Notably, 4.0S. pierrei-L/BAM-HA exhibited the strongest activity against Bacillus cereus (MIC and MBC: 4 mg/mL). This research highlights the potential of S. pierrei/BAM-HA composites as antibacterial coatings for implants and bone tissue engineering, while suggesting that further modifications may be needed to enhance antifungal properties.

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This research reports on the fabrication and electrochemical characterisation of a new nanocomposite Cu-MOF/MXene for supercapacitor applications. The composite was synthesised through a hydrothermal method involving Ti₃C₂ MXene and a copper-based metal-organic framework (Cu-MOF). X-ray diffraction (XRD) demonstrated formation of the two constituents and high crystallinity, while scanning electron microscopy (SEM) showed dispersal Cu-MOF microcrystals measuring 300–700 nm in size over MXene sheets of size 500-1000 nm. FTIR and photoluminescence (PL) spectroscopy proved strong interfacial interactions, confirming that the composite exhibited an emission peak at 561 nm with a band gap of 2.21 eV. Tauc analysis showed clear optical properties in the visible detection range, and thus Zeta potential showed a surface charge of -18.9 mV which ensures good colloidal stability. Electrochemical impedance spectroscopy (EIS) values demonstrated a charge transfer resistance of 120 Ω and an apparent electron transfer rate of 3.17×10⁻² cm/s. Cyclic voltammetry (CV) confirmed a high specific capacitance of 400 F/g at 5 mV/s and GCD analysis showed a value of 187.5 F/g for 1.0 A/g. The material showed retaining approximately70% of the initial capacitance after 5000 cycles, confirming the superb long-term stability. These results confirm the synergistic development of the MXene/Cu-MOF composite, making it a strong candidate for high-performance energy storage devices.

In this research, alumina/talc nanocomposite was synthesized for the first time and used to remove bromocresol green as a dye pollutant from aqueous solution. The synthesized nanocomposite was identified and confirmed by Fourier transform infrared spectroscopy, X-ray diffraction analysis, scan electron microscopy, energy dispersive X-ray spectroscopy and nitrogen adsorption and desorption isotherm. The adsorption experiments of bromocresol green dye on alumina/talc nanocomposite were designed and performed based on the design of experiment software by response surface method and central cube design. In the design of experiments, factors including pH, initial concentration of bromocresol green, alumina/talc nanocomposite dose, contact time and temperature were investigated. The maximum adsorption percentage obtained 98.43% at optimal conditions: pH = 2.06; in the initial concentration, 8.83 mg/L; adsorbent dose, 0.035 g; contact time, 32 min; and temperature, 25 °C. Among Langmuir, Freundlich and Temkin isotherms, the desired adsorption followed the Langmuir isotherm model with a regression coefficient of 0.9955 and the maximum adsorption capacity of 147.06 mg/g. The thermodynamic investigation of the adsorption process indicated that all three quantities of Gibbs free energy, enthalpy, and entropy changes were negative and therefore, the process was spontaneity, exothermic, and reducing disorder, respectively, especially at 25 °C. In addition, among four kinetic models, zero order, pseudo first order, pseudo second order and Higuchi model, the most appropriate kinetic model is the pseudo-second order model with a regression coefficient of 0.9992.

Thickness-dependent laser-induced thermoelectric voltage (LITV) effect via a semiconductor laser with a wavelength of 405 nm in the inclined solution-derived Bi₂Sr₂CuO_y (Bi2201) thin films has been studied. The high peak voltage of 47.6 mV under a power density of 50 mW/cm², and a large sensitivity of 0.93 ± 0.007 V·cm²/W (or 23.3 ± 0.18 V/mJ) are derived with the optimized thickness of 280 nm. The peak voltage demonstrates an initial increase and then a decrease with the increased film thickness, which is ascribed to the varied temperature difference caused by the gradually prolonged thermal transfer distance, increased light absorption, and enhanced electric conductance. Based on such LITV effect, the optical communication system composed of the transistor-transistor-logic modulated laser diode and the Bi2201 thin film was designed and realized. The separate and distinguished pseudorandom binary sequence can be transmitted and decoded correctly by this communication system. All these results will provide a way to optimize Bi2201 thin films with improved LITV and expand their performance in optical detection.

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Voltage self-produced makes the LITV effect important and valuable for broadband light detection. However, the expensive and large-sized excimer lasers restrict their practical application. Here, high peak voltage and large sensitivity with a commercial semiconductor laser are derived. Based on the optimized film device and its laser-induced self-produced voltage, optical communication was presented for the first time as one typical application of the LITV effect.