Search Results (131)

Fe^II-doped zinc ferrite nanocrystals (Fe^II_xZn_1-xFe^III₂O₄) were prepared via a sol–gel approach in the presence of polyvinyl alcohol as a stabilizer and assessed for their capability to eliminate crystal violet (CV) dye from water-based solutions. The structural and surface characteristics of the prepared materials were examined by XRD, HRTEM, FESEM, ATR–FTIR, XPS, UV–visible spectrophotometer and BET analyses. XRD patterns confirmed the formation of a cubic spinel ferrite structure (Fd-3m), indicating successful incorporation of Fe^II into the ZnFe₂O₄ lattice. ATR–FTIR spectra showed characteristic metal–oxygen vibrations at the tetrahedral and octahedral sites. XPS analysis confirmed the coexistence of Fe^II and Fe^III species, which may promote interfacial charge transfer and redox reactions. HRTEM and FESEM images showed particle agglomeration and grain growth after calcination at 700 °C. Fe^II_0.2Zn_0.8Fe^III₂O₄ exhibited the highest photocatalytic performance, achieving 97.2% degradation of CV under optimized conditions. The effects of contact time, catalyst dosage, initial dye concentration, and pH were systematically studied. The maximum removal efficiency was obtained at pH 10 using 0.075 g catalyst for 20 mg L⁻¹ CV solution within 40 min. Freundlich isotherm models exhibited the strongest correlation (R² = 0.918), pointing to multilayer adsorption occurring across a non-uniform nanoparticle surface. The Dubinin–Radushkevich analysis returned an adsorption energy of 3.01 kJ mol⁻¹, implying that physical forces predominantly control the adsorption mechanism. Kinetic investigations revealed a two-stage CV uptake pathway: fast initial binding at exterior surface sites, succeeded by a slower migration of dye molecules into the internal pores of the adsorbent. Full article

Micro-fabrication and structural engineering of an ultrasensitive photoelectrochemical (PEC) micro-sensing platform have been developed, based on ZnO inverse opal electrodes with signal amplification enhanced by AgCuS nanocrystals, specifically designed for the detection of anti-LGI1 antibodies. The delayed light effect inherent in the ZnO inverse opal structure enhances photoelectrochemical efficiency by extending the effective optical path. Incorporation of AgCuS nanocrystals significantly augments the photoelectric sensitivity of the ZnO inverse opal, maximizing visible light utilization, accelerating charge transfer kinetics, and substantially enhancing photocurrent generation. Leveraging the uniform porous architecture of the ZnO inverse opal, the ZnO/AgCuS film provides an expansive surface area for biomolecule immobilization and facilitates enhanced electron transport. The ZnO/AgCuS heterogeneous film was innovatively implemented as a PEC bioassay platform. Under optimized conditions, the biosensor exhibited a linear detection range of 0.01–500 ng/mL and a detection limit of 13 pg/mL for Anti-LGI1. Furthermore, the fabricated PEC biosensor demonstrated robust performance in human serum sample analyses, characterized by high repeatability, long-term stability, and excellent specificity. This work proposes a micro-manufacturing strategy for high-performance PEC biodevices, promoting the development of intelligent diagnostic platforms for autoimmune encephalitis. Full article

ZnS is one of the most promising wide-bandgap semiconductors for optoelectronic and sensing applications owing to its efficient ultraviolet–blue emission, high exciton binding energy, and chemical stability. However, the synthesis of ZnS nanocrystals in silicon-compatible porous matrices remains largely unexplored. In this work, ordered arrays of ZnS nanocrystals were synthesized for the first time in SiO₂/Si track templates fabricated by swift heavy ion irradiation followed by selective chemical etching. ZnS nanocrystals were deposited by electrochemical deposition from aqueous solutions containing ZnCl₂ and thiourea precursors. The structural, optical, and electrical properties of the resulting ZnS/SiO₂/Si nanocomposites were investigated using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, photoluminescence spectroscopy, and electrical measurements. The fabricated templates contained vertically aligned pores with a density of approximately 10⁸ cm⁻² and an average diameter of about 500 nm. Electrochemical deposition resulted in a pore filling efficiency of approximately 88%. X-ray diffraction analysis confirmed the formation of crystalline ZnS with a cubic zinc blende structure. The nanocomposites exhibit intense ultraviolet–blue photoluminescence in the 335–477 nm range, with pronounced emission peaks at 372 and 400 nm characteristic of ZnS nanocrystals. Current–voltage measurements indicate predominantly electronic conductivity, with a conductivity of 1.54 × 10⁻⁶ Ohm⁻¹·cm⁻¹, comparable to values reported for polycrystalline ZnS films. To support the experimental observations, the electronic structure of ZnS was analyzed using density functional theory within the LCAO framework. The calculated bandgap of 3.4 eV is consistent with previously reported theoretical and experimental data. The obtained results demonstrate that SiO₂/Si track templates provide a promising platform for the fabrication of ordered ZnS nanoarrays with potential applications in silicon-compatible optoelectronic and sensing devices. Full article

The application of lignin-based films is often restricted by traditional processing methods that rely on toxic organic solvents and harsh chemical reagents, which result in poor compatibility with the polymer matrix and difficulty balancing transparency, barrier, and toughness. Here, lignin was green-modified by ternary deep eutectic solvent (choline chloride-lactic acid-ethanol), and ZnO hybrids with cellulose nanocrystals (CNC) as anchor points were introduced to realize the stability and uniform dispersion of ZnO in the polyvinyl alcohol (PVA) matrix. The prepared composite film maintains a transmittance of about 78% at 800 nm while achieving a wide spectrum of ultraviolet shielding. The barrier properties of the film were markedly improved: the water vapor permeability (WVP) decreased to 0.24 × 10⁻⁷ g·m⁻¹·h⁻¹·Pa⁻¹, and the oxygen permeability (OTR) to 6.98 cm³·m⁻²·24 h⁻¹·0.1 MPa⁻¹. In addition, the mechanical flexibility and durability of the material were significantly improved, as evidenced by a tensile strain of 109%. In the insurance experiment, compared with the blank film, the browning degree and weight loss of the composite film were relatively low. The scalable and low-solvent consumption route provides a practical idea for the application of lignin in food preservation. Full article

In this study, a cellulose nanocrystal (CNC)-supported Ag–ZnO nanocomposite was synthesized via a hydrothermal route as a polymeric photocatalyst for efficient UV-A light-driven dye degradation. The renewable CNC framework provides abundant hydroxyl functional groups for nanoparticle anchoring, enhancing dispersion and interfacial charge transfer. Structural (XRD, FTIR, TEM, PL, and XPS) and thermal (TGA and DTG) analyses confirm successful incorporation of Ag nanoparticles and retention of CNC crystallinity. The composite exhibits a reduced optical bandgap (3.02 eV) and demonstrates superior photocatalytic activity, achieving 96% methylene blue (MB) degradation within 120 min. Enhanced performance is attributed to the synergistic effect of Ag-induced plasmonic excitation and CNC-facilitated charge migration, effectively suppressing ZnO photocorrosion. Moreover, the optimization of the parameters was conducted and found to be pH 7, a catalyst dose of 0.3 g L⁻¹, and an initial MB concentration of 10 ppm, which shows the best photocatalytic degradation reaction. The CNC/Ag–ZnO catalyst maintains 87% activity after five reuse cycles, showing good stability and reusability. The photostability of the CNC/Ag–ZnO catalyst was evaluated by ICP-MS, which measured Zn²⁺ concentration in the aqueous solution. Additionally, the degraded MB compounds were identified using GC-MS/MS analysis. This work highlights the potential of polymer-based biogenic supports for sustainable photocatalyst design and bridges polymer science with environmental remediation technology. Full article

The growing demand for environmentally responsible lubricants motivates the use of bio-based base stocks and benign solid additives. This study assesses the tribological performance of two Amazonian vegetable oils, Carapa guianensis (andiroba) and Copaifera spp. (copaiba resin) and a paraffinic mineral oil (PNL30) formulated with different zinc oxide (ZnO) particles, namely nanocrystals and microcrystals, at 0.01, 0.05, and 0.10 wt.%. Reciprocating sliding tests, coupled with 3D profilometry, viscosity, and sedimentation analyses, were used to link dispersion stability with friction and wear responses. A preliminary stability screening constrained the practical loading window to ≤0.10 wt.% for reproducible suspensions. Performance depended on the interplay between particle type and base-oil chemistry. Andiroba exhibited the most pronounced gains, with ZnO microcrystals near 0.05 wt.% delivering the best friction outcomes and the largest wear reductions (up to ~35%). In copaiba resin oil, nanocrystals produced small, sometimes non-significant improvements, whereas microcrystals tended to worsen wear consistent with abrasive third-body effects in a less polar matrix. In PNL30, the overall benefits were modest: nanocrystal additions generally increased wear, whereas microcrystals particularly at the highest loading 0.10 wt.% achieved a 36.4% reduction in SWR, representing a measurable and statistically significant improvement in wear resistance. These results highlight that eco-efficient lubricant design should co-optimize particle characteristics and dosage with base-oil polarity and film-forming tendencies, prioritizing dispersion stability alongside tribological targets. Full article

Transition metal (TM)-doped zinc oxide (ZnO) and zirconium dioxide (ZrO₂) nanocrystals exhibit complex correlations between crystal structure, defect chemistry, vibrational properties, and magnetic behavior that are strongly governed by synthesis route and dopant incorporation mechanisms. This review critically summarizes recent progress on Fe-, Mn-, and Co-doped ZnO and ZrO₂ nanocrystals synthesized by wet chemical, hydrothermal, and microwave-assisted hydrothermal methods, with emphasis on synthesis-driven phase evolution and apparent solubility limits. ZnO and ZrO₂ are treated as complementary host lattices: ZnO is a semiconducting, piezoelectric oxide with narrow solubility limits for most 3d dopants, while ZrO₂ is a dielectric, polymorphic oxide in which transition metal doping may stabilize tetragonal or cubic phases. Structural and microstructural studies using X-ray diffraction, electron microscopy, Raman spectroscopy, and Mössbauer spectroscopy demonstrate that at low dopant concentrations, TM ions may be partially incorporated into the host lattice, giving rise to diluted or defect-mediated magnetic behavior. When solubility limits are exceeded, nanoscopic secondary oxide phases emerge, leading to superparamagnetic, ferrimagnetic, or spin-glass-like responses. Magnetic measurements, including DC magnetization and AC susceptibility, reveal a continuous evolution from paramagnetism in lightly doped samples to dynamic magnetic states characteristic of nanoscale magnetic entities. Vibrational spectroscopy highlights phonon confinement, surface optical phonons, and disorder-activated modes that sensitively reflect nanocrystal size, lattice strain, and defect populations, and often correlate with magnetic dynamics. Rather than classifying these materials as diluted magnetic semiconductors, this review adopts a synthesis-driven and correlation-based framework that links dopant incorporation, local structural disorder, vibrational fingerprints, and magnetic response. By emphasizing multi-technique characterization strategies required to distinguish intrinsic from extrinsic magnetic contributions, this review provides practical guidelines for interpreting magnetism in TM-doped oxide nanocrystals and outlines implications for applications in photocatalysis, sensing, biomedicine, and electromagnetic interference (EMI) shielding. Full article

AgI and ZnI₂ nanocrystals are key components for AgI-ZnI₂-SiO₂ hybrid powders (HPs), which could be potentially important for atmospheric artificial precipitation technology. HPs were created by the “Hydrothermal template cocondensation” method (“HTC” method). Mesoporous silica dioxide (MCM48, MCM41, SBA15, SBA16), silver iodides, and zinc iodides were simultaneously grown under specific conditions. The influence of silica dioxide on AgI and ZnI₂ nanocrystals characteristics (phase, size, and thermal stability) were studied using various physicochemical analysis methods. In addition to crystal features, some structural and textural properties of the AgI-ZnI₂-SiO₂ hybrid as an individual agglomerate and its morphology were determined. This showed that nanocrystal features were dependent on synthesis condition. The influence of the nature of the reagent, which is pH-forming, was manifested at the initial stage of the process, and the morphology of the silica dioxide matrix controlled the crystal properties during the post-synthesis phase. It was established that the thermal stability of AgI and ZnI₂ nanocrystals increased due to the protective shielding function of that SiO₂ matrix. Full article

Electrolysis and biological processes, such as fermentation and microbial electrolysis cells, offer efficient hydrogen production alongside wastewater treatment. This study presents a novel microbial electrolyzer (ME) comprising a titanium dioxide (TiO₂) anode, a nickel–iron–carbon (NiFeC) cathode, and a cellulose nanocrystal proton exchange membrane (CNC-PEM) designed to generate hydrogen from palm oil mill effluent (POME). The system is powered by a 12 V electric double-layer organic supercapacitor (EDLOSC) integrated with a ZnO/PVA-based solar thin film. Power delivery to the TiO₂-NiFeC-PEM electrolyzer is optimized using an Adaptive Neuro-Fuzzy Inference System (ANFIS). Laboratory-scale pilot tests demonstrated effective degradation of POME’s organic content, achieving a hydrogen yield of approximately 60%. Additionally, the nano-structured ZnO/CuO–ZnO/PVA solar film facilitated stable power supply, enhancing in situ hydrogen production. These results highlight the potential of the EDLOSC-encased ZnO/PVA-powered electrolyzer as a sustainable solution for hydrogen generation and industrial wastewater treatment. Full article

Enhancing the mechanical strength of transparent glass-ceramics (TGCs) without compromising their optical performance remains a key challenge for advanced optical and photonic materials. Among aluminosilicate systems, ZnO–MgO–Al₂O₃–SiO₂ (ZMAS) glasses are particularly attractive due to their ability to form ZnAl₂O₄-based nanostructures; however, their ion-exchange (IE) strengthening has not been systematically explored due to the absence of single-charged cations in their composition. In this study, a sodium-modified ZMAS glass was developed to enable efficient chemical strengthening while preserving glass-forming ability and optical clarity. Controlled two-stage heat treatment produced TGCs containing 5 mol% Na₂O, composed solely of ZnAl₂O₄ (gahnite) nanocrystals with an average size of 4–5 nm. The obtained TGCs showed a Vickers hardness of ~8.5 GPa, increasing to ~10–10.5 GPa after ion exchange in molten KNO₃ at 450 °C, without changes in phase composition or optical transmittance. Compared with literature data on alkali-containing TGCs, the developed material demonstrates a higher hardness level while maintaining full transparency. The results reveal a practical route toward chemically strengthened ZnAl₂O₄-based glass-ceramics combining optical clarity, high hardness, and damage tolerance for optical, photonic, and protective applications. Full article

Interactions of ZnO nanoplates with water are crucial in determining its structure and performance of the catalyst, yet the details for these processes remain missing due to the lack of an effective detection method that provides resolution at the atomic level. Here, ¹⁷O solid-state NMR spectroscopy is applied to investigate the interactions and the associated stabilization mechanisms for the polar surface of ZnO nanoplates. It shows that the specific O sites (around Zn vacancy) on the polar surface also contribute to the ¹⁷O NMR signal at −18.8 ppm. The observed trends in both ¹⁷O and ¹H spectra after exposing to water vapor further support the assignment of this ¹⁷O high-frequency signal (−18.8 ppm). In addition, the dissociation of water at defective sites of polar surfaces is evidenced, which leads to the generation of OH groups on both (000$\overline{1}$)-O and (0001)-Zn surfaces. The generated OH species obviously improves the dispersity of ZnO nanocrystals, as well as the stability of polar facets by significant electrostatic repulsion interactions. This study will provide insight into the adsorption properties of water on polar facets and the related stabilization mechanisms of the polar surface in nanocrystals. Full article

In this study, we investigate the phase transition process during high-alumina, low-lithium glass-ceramics (ZnO-MgO-Li₂O-SiO₂-Al₂O₃) crystallization. The differential scanning calorimetry and high-temperature X-ray diffraction results show that approximately 10 wt.% of (Zn, Mg)Al₂O₄ crystals precipitated when the heat treatment temperature reached 850 °C, indicating that a large number of nuclei had already formed during the earlier stages of heat treatment. Field emission transmission electron microscopy used to observe the microstructure of glass-ceramics after staged heat treatment revealed that cation migration occurred during the nucleation process. Zn and Mg aggregated around Al to form (Zn, Mg)Al₂O₄ nuclei, which provided sites for crystal growth. Moreover, high-valence Zr aggregated outside the glass network, leading to the formation of nanocrystals. Raman spectroscopy analysis of samples at different stages of crystallization revealed that during spinel precipitation, the Q³ and Q⁴ structural units in the glass network increased significantly, along with an increase in the number of bridging oxygens. Highly coordinated Al originally present in the network mainly participated in spinel nucleation, effectively suppressing the subsequent formation of Li_xAl_xSi_1−xO₂, which eventually resulted in the successful preparation of glass-ceramics with (Zn, Mg)Al₂O₄ and ZrO₂ as the main crystalline phases. The grains in this glass-ceramic are all nanocrystals. Its Vickers hardness and flexural strength can reach up to 875 Hv and 350 MPa, respectively, while the visible light transmittance of the glass-ceramic reaches 81.5%. This material shows potential for applications in touchscreen protection, aircraft and high-speed train windshields, and related fields. Full article

Background/Objectives: Clostridium perfringens is a normal inhabitant of the intestinal tract of poultry, and it has the potential to induce cholangiohepatitis and necrotic enteritis (NE). The poultry industry suffers significant financial losses because of NE, and treatment becomes more challenging due to resistant C. perfringens strains. Methods: The antimicrobial and antibiofilm activities of cellulose nanocrystals/zinc oxide nanocomposite (CNCs/ZnO) were assesses against pan drug-resistant (PDR) C. perfringens isolated from chickens and turkeys using phenotypic and molecular assays. Results: The overall prevalence rate of C. perfringens was 44.8% (43.75% in chickens and 58.33% in turkeys). Interestingly, the antimicrobial susceptibility testing of C. perfringens isolates revealed the alarming PDR (29.9%), extensively drug-resistant (XDR, 54.5%), and multidrug-resistant (MDR, 15.6%) isolates, with multiple antimicrobial resistance (MAR) indices ranging from 0.84 to 1. All PDR C. perfringens isolates could synthesize biofilms; among them, 21.7% were strong biofilm producers. The antimicrobial potentials of CNCs/ZnO against PDR C. perfringens isolates were evaluated by the agar well diffusion and broth microdilution techniques, and the results showed strong antimicrobial activity of the green nanocomposite with inhibition zones’ diameters of 20–40 mm and MIC value of 0.125 µg/mL. Moreover, the nanocomposite exhibited a great antibiofilm effect against the pre-existent biofilms of PDR C. perfringens isolates in a dose-dependent manner [MBIC50 up to 83.43 ± 1.98 for the CNCs/ZnO MBC concentration (0.25 μg/mL)]. The transcript levels of agrB quorum sensing gene and pilA2 type IV pili gene responsible for biofilm formation were determined by the quantitative real time-PCR technique, pre- and post-treatment with the CNCs/ZnO nanocomposite. The expression of both genes downregulated (0.099 ± 0.012–0.454 ± 0.031 and 0.104 ± 0.006–0.403 ± 0.035, respectively) when compared to the non-treated isolates. Conclusions: To the best of our knowledge, this is the first report of CNCs/ZnO nanocomposite’s antimicrobial and antibiofilm activities against PDR C. perfringens isolated from chickens and turkeys. Full article

Energy levels associated with several crystalline defects, such as zinc (V_Zn) and oxygen (V_O) vacancies, Zn and O interstitials (Zn_i and O_i respectively), Zn and O antisite defects, and charged oxygen vacancies Vo-, among others, are generated by the introduction of cobalt (Co) into the structure. The effective introduction of Co into the Zn occupancy site was evaluated by XRD and electron paramagnetic resonance. The EPR spectra remain consistent across all doping concentrations of Co²⁺ ions and revealed intriguing features linked to four distinct Co²⁺ paramagnetic centers; among them, a pair of Co²⁺ ions exhibited ferromagnetic coupling. ZnO nanocrystals doped with cobalt were produced by sol gel and their use as photocatalysts were evaluated in the degradation of the Congo red pollutant. The degradation efficiency improved by more than 50% when compared to the efficiency of pure ZnO nanocrystals at the same activity time. Full article