Search Results (2,114)

La-doped ZnO nanoclusters confined within mesoporous SBA-15 were synthesized using an impregnation–calcination method and evaluated for their visible-light-driven photocatalytic degradation of Rhodamine B (RhB). Small-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the preservation of the 2D hexagonal mesostructure of SBA-15 post-loading. In contrast, wide-angle XRD and Fourier-transform infrared spectroscopy (FT-IR) analyses revealed that the incorporated ZnO existed predominantly as highly dispersed amorphous or ultrafine clusters within the mesopores. N₂ adsorption–desorption measurements exhibited Type IV isotherms with H1 hysteresis loops. Compared to pristine SBA-15, the specific surface area and pore volume of the composites decreased from 729.35 m² g⁻¹ to 521.32 m² g⁻¹ and from 1.09 cm³ g⁻¹ to 0.85 cm³ g⁻¹, respectively, accompanied by an apparent increase in the average pore diameter from 5.99 nm to 6.55 nm, attributed to non-uniform pore occupation. Under visible-light irradiation, the photocatalytic performance was highly dependent on the La doping level. Notably, the 5% La-ZnO/SBA-15 sample exhibited superior activity, achieving over 99% RhB removal within 40 min and demonstrating the highest apparent rate constant (k = 0.1152 min⁻¹), surpassing both undoped ZnO/SBA-15 (k = 0.0467 min⁻¹) and other doping levels. Reusability tests over four consecutive cycles showed a consistent degradation efficiency exceeding 93%, with only a ~7 percentage-point decline, indicating excellent structural stability and recyclability. Radical scavenging experiments identified h⁺, ·OH, and ·O₂⁻ as the primary reactive species. Furthermore, photoluminescence (PL) quenching observed at the optimal 5% La doping level suggested suppressed radiative recombination and enhanced charge carrier separation. Collectively, these results underscore the synergistic effect of La doping and mesoporous confinement in achieving fast, efficient, and recyclable photocatalytic degradation of organic pollutants. Full article

ZnNb₂O₆-based microwave dielectric ceramics have attracted considerable attention due to their high quality factor (Q × f) and low sintering temperature, but their application was limited by poor temperature stability with a large negative temperature coefficient of resonant frequency (τ_f). Herein, novel (1 − x)ZnNb₂O_6−xCa_0.5Sr_0.5TiO₃ (x = 0.05–0.125) composite ceramics were designed and fabricated. The used ZnNb₂O₆ and Ca_0.5Sr_0.5TiO₃ were synthesized through solid-phase reaction by using stoichiometric metal oxides or carbonates as the raw materials at 650 and 1100 °C, respectively. The composite ceramics were prepared by solid-state sintering, and the sintering parameters were optimized at 1175 °C for 4 h by visual high-temperature deformation analysis. A focus was paid on the temperature stability and compositional effects of Ca_0.5Sr_0.5TiO₃ of the obtained composited ceramics. As the Ca_0.5Sr_0.5TiO₃ content increases, the dielectric constant (ε_r) and Q × f gradually decrease, while τ_f shifts toward positive values. At x = 0.075, the composite ceramics sintered at 1175 °C for 4 h exhibit near-zero τ_f (−8.99 ppm/°C), coupled with ε_r = 23.23 and Q × f = 21,686 GHz. This study provides theoretical guide and material support for designing and fabricating various high-performance thermally stable microwave dielectric ceramics for 5G communication devices and future communication technologies. Full article

The present study examined the microstructure and corrosion characteristics of MgCa4Zn1Gd1 and MgCa2Zn1Gd3 alloys that were coated with ZnO thin films, which were deposited by atomic layer deposition (ALD). Coatings of different thicknesses (42.5, 95.4 and 133.7 nm for 500, 1000, and 1500 cycles, respectively) were characterized using X-ray diffraction (XRD), Raman spectroscopy, SEM/EDS, AFM (atomic force microscope), and FTIR (Fourier transform infrared spectroscopy). XRD and Raman analyses were conducted to verify the formation of crystalline zinc oxide (ZnO) with a homogeneous granular morphology. Surface roughness decreased with increasing coating thickness, reaching the lowest values for the 1500-cycle ZnO layer on MgCa2Zn1Gd3 (R_a = 7.65 nm, R_s = 9.8 nm). Potentiodynamic and immersion tests in Ringer solution at 37 °C revealed improved corrosion resistance for thicker coatings, with the lowest hydrogen evolution (20.89 mL·cm⁻²) observed for MgCa2Zn1Gd3 coated after 1500 cycles. Analysis of corrosion products by FTIR identified Mg(OH)₂ and MgCO₃ as dominant and then MgO and ZnO. Phase analysis also indicated the presence of ZnO coating after 100 h of immersion. The ZnO film deposited after 1500 ALD cycles on MgCa2Zn1Gd3 provides the most effective corrosion protection and is a promising solution for biodegradable magnesium implants. Full article

Wastewater can be reused in industrial processes, for domestic activities, and for agriculture. This is a strategy to address the global water shortage. Consequently, there is an ongoing search for new materials that can effectively remove contaminants from wastewater, as dyes are considered persistent pollutants. This study synthesized films based on polysulfone with chemically modified ZnO nanoparticles by the sonochemical method for application as an adsorbent material for indigo and crystal violet. The films were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Thermogranimetric analysis (TGA), and Scanning Electron Microscopy (SEM); changes were observed with the incorporation of the nanoparticles. The results reveal that the films achieved a dye removal of 80 mg/g. The crystallite size was measured using the Scherrer equation for the polysulfone (PSF) sample, which was 0.024 nm, and using the same method the result obtained was 0.048 nm for the PSFZNO2 sample. The modification with L-serine is novel, as it is an amino acid and a non-toxic substance for the human body. There are few studies on this type of reagent regarding the modification of nanoparticles to provide them with different functionalities. This work was carried out in accordance with the principles of green chemistry, specifically using ultrasound technology, which promotes principles 6 and 9 by reducing energy consumption through the use of lower temperatures and short reaction times. Principles 2 and 3 are also addressed by modifying the surface of the nanoparticles directly. This process eliminates the need for intermediate steps or the use of highly toxic reagents. Full article

The present work systematically investigates the impact of multilayer architecture—specifically 5, 10, and 15 layers—on the structural, morphological, optical, and dielectric properties of zinc oxide (ZnO) thin films, aiming to tailor their characteristics for optoelectronic applications. The films were characterized using a comprehensive suite of techniques. X-ray diffraction (XRD) analysis of the 15-layer sample confirmed the formation of polycrystalline ZnO with a hexagonal wurtzite crystal structure, showing prominent (100), (002), and (101) diffraction peaks. Measurements indicated that the film thickness progressively increased from 43.81 nm for 5 layers to 80.68 nm for 15 layers. Concurrently, the surface roughness significantly decreased from 5.54 nm (5 layers) to 2.00 nm (15 layers) with increasing layer count, suggesting enhanced film quality and densification. Optical studies using ultraviolet–visible (UV-Vis) spectroscopy revealed an increase in absorbance and a corresponding decrease in transmittance in the UV-Vis spectrum as the film thickness increased. The calculated optical band gap showed a slight redshift, decreasing from 3.26 eV for the 5-layer film to 3.23 eV for the 15-layer film. Photoluminescence (PL) spectra exhibited characteristic near-band-edge UV emission, with the 5-layer film demonstrating the highest PL intensity. Furthermore, analysis of optical constants revealed that the refractive index, extinction coefficient, optical conductivity, and both the real and imaginary parts of the dielectric constant generally increased with an increasing number of layers, particularly in the visible region, while more nuanced and non-monotonic trends were observed in the UV range. These results underscore the significant influence of layer number on the physical properties of ZnO thin films, providing valuable insights for optimizing their performance in various optoelectronic devices. Full article

The influence of synthesis method on the properties of Zn_1−xFe_xO nanoparticles with different Fe doping levels (x = 0, 0.01, 0.03, and 0.05) for Congo Red (CR) adsorption was investigated. Nanoparticles were prepared by sol–gel and coprecipitation and characterized by XRD, SEM-EDS, FTIR, and BET analyses. Sol–gel synthesis produced smaller particles (~13 nm) than coprecipitation (~35 nm), and both the method and calcination temperature strongly affected crystallite size. Sol–gel nanoparticles showed significantly higher adsorption efficiency (~90%) due to their larger BET surface area, greater BJH pore volume, and smaller particle size, which increased the number of accessible active sites. In contrast, coprecipitation nanoparticles exhibited a much lower adsorption capacity (~24%). Fe incorporation further enhanced performance by introducing lattice distortions and oxygen vacancies, as evidenced by XRD peak broadening and increased lattice strain. SEM images displayed particle growth and compaction after adsorption, particularly in doped samples. Temperature-dependent experiments indicated that undoped ZnO lost efficiency at 60 °C due to weak physical interactions, whereas Fe-doped nanoparticles maintained high adsorption, due to improved stability of the adsorbent-adsorbate bond. The combination of Fe doping and sol–gel synthesis significantly improved the properties of ZnO, yielding highly efficient adsorbents suitable for environmental remediation. Full article

Background: Individualized care in veterinary practice optimizes pharmaceutical dose regimens, facilitates disease prevention, and supports animal health by considering the animal’s individual profile. Three-dimensional (3D) printing is a suitable technology for manufacturing both tailored drugs and supplements with enhanced efficacy and reduced adverse reactions. Zinc is used to correct deficiencies, support growth, boost the immune system, and treat specific conditions like zinc-responsive dermatosis in dogs. The purpose of the study was to develop and analyze tailored zinc-loaded filaments for the design of custom-made 3D-printed shapes. Methods: Zinc oxide (ZnO) and artificial beef flavor were incorporated into hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC), respectively, to produce tailored 5% or 10% ZnO-containing filaments for 3D printing. The obtained filaments and 3D-printed forms were characterized using sieve analysis, moisture determination, melting point, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction analysis. Results: The characterization of two placebo and four custom-made 3D-printed ZnO supplements suggested that HPMC is a polymer with poor processability, whereas HPC is suitable for incorporating artificial beef flavor and ZnO. FTIR analysis indicated no interaction between the components. Conclusion: The HPC and 10% flavor mixture can be applied as a matrix for manufacturing 3D-printed forms with ZnO for individualized animal care. Full article

The development of advanced semiconductor-based catalysts for the rapid degradation of emerging pharmaceutical pollutants in water remains a critical challenge in environmental science. In this study, we present the synthesis, characterization, and catalytic performance of zinc oxide (ZnO) microtetrapods decorated with plasmonic Ag nanoparticles. These microtetrapods have been designed to enhance piezo-, photo-, and piezo-photocatalytic degradation of metronidazole (MNZ), a persistent antibiotic contaminant. ZnO microtetrapods were synthesized by high-temperature pyrolysis and using atmospheric-pressure microwave nitrogen plasma, followed by photochemical deposition of Ag nanoparticles at various precursor concentrations (0–1 mmol AgNO₃). The structural integrity of the samples was confirmed through X-ray diffraction (XRD) analysis, while the morphology was examined using scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). Additionally, spectroscopic analysis, including Raman, electron paramagnetic resonance (EPR), and photoluminescence (PL) spectroscopy, was conducted to verify the successful formation of heterostructures with adjustable surface loading of Ag. It has been shown that ZnO microtetrapods decorated with plasmonic Ag nanoparticles exhibit Raman-active properties. A systematic evaluation under photocatalytic, piezocatalytic, and combined piezo-photocatalytic conditions revealed a pronounced volcano-type dependence of catalytic activity on Ag content, with the 0.75 mmol composition exhibiting optimal performance. In the presence of both light irradiation and ultrasonication, the optimized Ag/ZnO composite exhibited 93% degradation of MNZ within a span of 5 min, accompanied by an apparent rate constant of 0.56 min⁻¹. This value stands as a significant improvement, surpassing the degradation rate of pristine ZnO by over 24-fold. The collective identification of defect modulation, plasmon-induced charge separation, and piezoelectric polarization as the predominant mechanisms driving enhanced reactive oxygen species (ROS) generation is a significant advancement in the field. These findings underscore the synergistic interplay between plasmonic and piezoelectric effects in oxide-based heterostructures and present a promising strategy for the efficient removal of recalcitrant water pollutants using multi-field activated catalysis. Full article

Zinc oxide (ZnO) thin films were deposited by radio-frequency reactive magnetron sputtering at a cryogenic substrate temperature of −78 °C to explore a novel low-thermal-budget route for semiconductor growth. Despite the extremely low temperature, X-ray diffraction revealed spontaneous partial crystallization of wurtzite ZnO upon warming to room temperature, driven by strain relaxation and stress coupling at the ZnO/SiO₂ interface. Atomic-force and scanning-electron microscopies confirmed nanoscale hillock and ridge morphologies that correlate with in-plane compressive stress and out-of-plane tensile strain. Spectroscopic ellipsometry, modeled using a general oscillator (GO) mathematical model approach, determined a film thickness of 60.81 nm, surface roughness of 3.75 nm, and a direct optical bandgap of 3.40 eV. Photoluminescence spectra exhibited strong near-band-edge emission modulated with LO-phonon replicas at 300 K, indicating robust exciton–phonon coupling. This study demonstrates that ZnO films grown at cryogenic conditions can undergo substrate-induced self-crystallize upon warming, which eliminates the need for thermal annealing. The introduced cryogenic self-crystallization regime offers a new pathway for depositing crystalline semiconductors on thermally sensitive or flexible substrates where heating is undesirable, enabling future optoelectronic and photonic device fabrication under ultra-low thermal-budget conditions. Full article

Layered transition-metal oxides are among the most promising sodium-ion battery cathodes owing to their high specific capacities and structurally tunable frameworks. However, the prototypical P2-Na_0.67Ni_0.33Mn_0.67O₂ (NM) undergoes an irreversible P2 → O2 phase transition at high voltages, accompanied by severe lattice strain and capacity fade, which hinders practical deployment. Here, we propose a cooperative regulation strategy that couples Zn/Al co-doping with Na enrichment, and successfully synthesize P2-Na_0.80Ni_0.14Zn_0.14Mn_0.58Al_0.14O₂ (NMZA-N14). The optimized NMZA-N14 delivers an initial discharge capacity of 125 mAh g⁻¹ at 0.1C and demonstrates exceptional cycling and rate performance, retaining 98.6% of its capacity after 100 cycles at 0.2C and 93.6% after 200 cycles at 1C. Kinetic analyses indicate a higher Na⁺ diffusion coefficient and a lower charge-transfer resistance in NMZA-N14, evidencing substantially accelerated ion transport. In situ X-ray diffraction further reveals a reversible P2 → OP4 phase transition in the high-voltage regime with a unit-cell volume change of only ~2.27%, thereby avoiding the irreversible structural degradation observed in NM. This synergistic modulation markedly enhances structural stability and electrochemical kinetics, providing a viable pathway for the rational design of high-performance sodium-ion battery cathodes. Full article

Understanding how the surface charge environment governs pollutant–catalyst interactions is essential for designing efficient photocatalysts. In this study, ZnO–CeO₂–WO₃ composite materials were synthesized through a simplex-centroid mixture design to evaluate their photocatalytic activity toward the degradation of 4-nitrophenol (4-NPOH) under UV irradiation. The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV–Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), nitrogen adsorption–desorption (BET/DFT) and scanning electron microscopy (SEM). Photocatalytic experiments were conducted without pH adjustment to analyze the intrinsic behavior of each oxide and their mixtures. The acid–base equilibrium of 4-NPOH (pK_a = 7.2) allowed evaluating its deprotonation to 4-nitrophenolate (4-NP⁻) and its interaction with the catalyst surface, which depends on the point of zero charge (pH_Pzc) of ZnO, CeO₂, and WO₃. The Zn–W binary system (ZnWO₄ phase) exhibited the highest activity, achieving 81% degradation efficiency and the largest apparent rate constant (k = 5.1 × 10⁻³ min⁻¹). However, a 51% decrease in activity was observed after three reuse cycles, attributed to WO₃ leaching induced by the interaction between 4-NPO⁻ and zinc tungstate hydroxide (Zn[W(OH)₈]). This work establishes a direct correlation between surface charge, pollutant speciation, and photocatalytic performance, providing a mechanistic framework for understanding pH-dependent degradation processes over multicomponent oxide composites. Full article

To enhance the electrical performance of MgZnO-TFTs, this study employed radio-frequency (RF) magnetron sputtering to fabricate MgZnO/ZTO thin films. Using these films as the channel layer, bottom-gate top-contact MgZnO/ZTO-TFT devices were constructed. The thin films were characterized using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). After optimization, the MgZnO/ZTO-TFT exhibited a high field-effect mobility of 16.80 cm²·V⁻¹·s⁻¹, high Ion/off of 7.63 × 10⁸, threshold voltage of −1.60 V, and subthreshold swing as low as 0.74 V·dec⁻¹. Bias stress stability tests were conducted under positive bias stress (PBS) and negative bias stress (NBS) conditions with a source-drain voltage of 20 V and gate bias stresses (VGS) of +10 V and −10 V, respectively, for a duration of 1000 s. The resulting threshold voltage shifts were only +0.58 V and −0.15 V, respectively, indicating excellent bias stability. These results suggest that the ZTO film, serving as the lower channel layer, effectively enhances carrier transport at the MgZnO/ZTO interface, thereby improving the field-effect mobility and on/off current ratio. Meanwhile, the MgZnO film as the upper channel layer adjusts the device’s threshold voltage and enhances its bias stability. Full article

In recent years, porous carbon-based materials have demonstrated their potential as electrode materials, particularly as supercapacitors for energy storage. The specific capacitance of a carbon-based material is strongly influenced by its porosity. Herein, activated biochar (BCA) from millet was prepared using ZnCl₂ as an activator at temperatures of 400, 700, and 900 °C. Activation was achieved through wet and dry impregnation of millet bran powder particles. The porosity of BCAs was assessed by determining the iodine and methylene blue numbers (N_I and N_MB, respectively), which provide information on microporosity and mesoporosity, respectively. Characterization of the BCAs was carried out using Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and cyclic voltammetry. The data show that the BCA prepared at 700 °C following dry impregnation, P700(p), has the highest N_I and the highest geometric mean value ($ñ=\sqrt{N_I\times N_{MB}}$), a descriptor we introduce to characterize the overall porosity of the biochars. P700(p) biochar exhibited remarkable electrochemical properties and a maximum specific capacitance of 440 F g⁻¹ at a current density of 0.5 A g⁻¹, in the three-electrode configuration. This value drops to 110 F g⁻¹, in the two-electrode configuration. The high specific capacitance is not due to ZnO, but essentially to the textural properties of the biochar (represented by ñ descriptor), and possibly but to a lesser extent to small amounts of Zn₂SiO₄ left over in the biochar. Moreover, the capacitance retention increases with cycling, up to 130%, thus suggesting electrochemical activation of the biochar during the galvanostatic charge-discharge process. To sum up, the combination of pyrolysis temperature and the method of impregnation permitted to obtaining of a porous biochar with excellent electrochemical properties, meeting the requirements of supercapacitors and batteries. Full article

Traditional nanoparticle synthesis methods often rely on hazardous chemicals, raising concerns about their environmental impact. This study reports the green synthesis of zinc oxide (ZnO) nanoparticles using aqueous extracts from three distinct parts of Agave tequilana: the stalk (ZnO-S), heart (ZnO-H), and leaves (ZnO-L). The aim was to explore the influence of the different plant parts, each with their respective phytochemical profile, on the structural, optical, and antibacterial properties of the resulting nanoparticles. The synthesized ZnO-NPs were extensively characterized using UV–Vis spectroscopy, ATR-FTIR, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS). The results revealed that ZnO-S exhibited the smallest particle size (~18.3 nm), the highest crystallinity, and the most uniform morphology. Optical analysis showed bandgap energies of 3.13 eV (ZnO-S), 2.99 eV (ZnO-H), and 3.02 eV (ZnO-L), with ZnO-S demonstrating enhanced UV absorption and reactive oxygen species (ROS) generation potential. Antibacterial assays against Staphylococcus aureus and Escherichia coli confirmed strong bactericidal activity for all samples, with ZnO-S showing the largest inhibition zones, approaching the efficacy of the reference antibiotic kanamycin. This work highlights the fundamental roles of plant-derived phytochemicals as natural reducing and capping agents and emphasizes the valorization of agave stalk and leaves, traditionally treated as agricultural waste for cost-effective and eco-friendly nanomaterial production. The findings reveal the untapped potential of Agave tequilana as a sustainable source for high-performance nanomaterials, paving the way for green innovations in antimicrobial and environmental applications. Full article

This study focuses on optimizing the photochemical degradation of methylene blue (MB) using calcium-functionalized zinc oxide–copper oxide–alginate (ZnO/CuO/Alg) nanocomposite hydrogel beads under sunlight irradiation. Pure ZnO and CuO nanoparticles (NPs) were synthesized via a green co-precipitation method employing plant extracts and were subsequently embedded into an alginate polymer matrix. Various characterization techniques, including powder X-ray diffraction (PXRD), ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray analysis (SEM–EDX), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA), were employed to analyze the structure and morphology of the catalysts. The photocatalytic performance of the nanocomposites was evaluated by studying the effects of pH, catalyst dose, irradiation time and MB concentration. Mathematical modeling was used to determine the optimal degradation conditions, achieving a maximum photocatalytic efficiency of 77.86% under the following parameters: MB concentration of 20 mg/L, catalyst dose of 50 mg, irradiation time of 75 min and pH 8. The model fit the experimental data well, showing a coefficient of determination (R²) of 0.963, confirming its reliability. Additionally, the antibacterial potential of the nanocomposite powders was investigated. Tests were conducted using equal concentrations of pure ZnO, ZnO/CuO and ZnO/CuO/Alg nanocomposites on Petri dishes inoculated with both Gram-positive and Gram-negative bacterial cultures. The results revealed significant bacterial growth inhibition, with the ZnO/CuO/Alg nanocomposite exhibiting the largest inhibition zone of 20 mm, compared to 14 mm for pure ZnO, indicating superior antibacterial efficacy. Full article