Search Results (75)

Brain ischemia is a severe condition caused by reduced cerebral blood flow, leading to the disruption of ion gradients in brain tissue. This imbalance triggers spreading depolarizations, which are waves of neuronal and glial depolarization propagating through the gray matter. Microelectrode arrays (MEAs) are essential for real-time monitoring of these electrophysiological processes both in vivo and in vitro, but their sensitivity and signal quality are critical for accurate detection of extracellular brain activity. In this study, we evaluate the performance of a flexible microelectrode array based on gold-coated zinc oxide nanorods (ZnO NRs), referred to as nano-fMEA, specifically for high-fidelity electrophysiological recording under pathological conditions. Acute mouse brain slices were tested under two ischemic models: oxygen–glucose deprivation (OGD) and hyperkalemia. The nano-fMEA demonstrated significant improvements in event detection rates and in capturing subtle fluctuations in neural signals compared to flat fMEAs. This enhanced performance is primarily attributed to an optimized electrode–tissue interface that reduces impedance and improves charge transfer. These features enabled the nano-fMEA to detect weak or transient electrophysiological events more effectively, making it a valuable platform for investigating neural dynamics during metabolic stress. Overall, the results underscore the promise of ZnO NRs in advancing electrophysiological tools for neuroscience research. Full article

This research examines the effect of annealing temperature on the growth orientation of zinc oxide (ZnO) nanorods and its subsequent influence on NO₂ gas sensing efficiency. Zinc oxide (ZnO) nanorods were synthesized using the chemical bath deposition method, followed by annealing at 300, 400, and 500 °C. Diffraction analysis confirmed that both non-annealed and annealed ZnO nanorods crystallize in a hexagonal wurtzite structure. However, increasing the annealing temperature shifts the growth orientation from the c-axis (002) toward the (100) and (101) directions. Microscopy images (FE-SEM) revealed a reduction in nanorod diameter as the annealing temperature increases. Optical characterization using UV–visible and photoluminescence spectroscopy indicated shifts in the band gap energy and emission properties. Contact angle measurements demonstrated the hydrophobic nature of the films. Gas sensing tests at 200 °C revealed that the ZnO thin film annealed at 400 °C achieved the highest NO₂ response of 5.88%. The study highlights the critical role of annealing in modifying the crystallinity, growth orientation, and defect states of ZnO thin films, ultimately enhancing their NO₂ detection capability. Full article

The adhesion of deleterious bacteria on titanium substrates not only causes economic losses but also endangers human life and health. The study is expected to address the challenging issues of using ZnO as an antibacterial material, including low bactericidal efficiency without lighting, susceptibility to ZnO cluster formation, and easy adhesion of bacteria to its surface. It is proposed that the prepared ZnO nanorod arrays with a hexagonal wurtzite structure on the surface of titanium-based materials can address the issue of ZnO cluster formation. Remarkably, a mere 3.49 g cm⁻² of decorated Ag/AgCl achieves over 99% sterilization efficiency without lighting. The incorporation of FAS (1H,1H,2H,2H-perfluorodecyltrimethoxysilane) molecules with low surface energy enables the prepared Ti@ZnO@Ag/AgCl@FAS to attain a Cassie–Baxter wetting state, thereby imparting exceptional bacterial anti-adhesion properties exceeding 99.50%. Furthermore, antibacterial and anti-adhesion models have been proposed to elucidate the underlying mechanisms. This innovative approach is anticipated to be adaptable for application across various material substrates, which opens up a new avenue for the application of the antibacterial and bacterial anti-adhesion properties on the surface of ZnO materials. Full article

This study explores the enhancement of α-Fe₂O₃ (hematite) nanorod arrays for photoelec-trochemical applications by constructing a Cu₂ZnSnS₄ (CZTS) heterojunction. While α-Fe₂O₃ offers good stability, a low cost, and environmental benefits, its efficiency is limited by slow oxygen evolution kinetics, high carrier recombination rates, and low conductivity. By introducing CZTS, a material with strong light absorption and charge transport properties, we enhance the separation of photogenerated charge carriers, reduce charge transfer resistance, and increase the carrier concentration, thereby boosting the overall photoelectrochemical performance. The experimental results show that a modified FC-15 photoanode achieves a photocurrent density of 3.40 mA/cm² at 1.60 V vs. RHE, a substantial increase compared to 0.40 mA/cm² for unmodified α-Fe₂O₃. Band gap analysis reveals a reduced band gap in the FC-15 material, enhancing light absorption and boosting the photoelectrocatalytic performance. In photoelectrochemical water-splitting tests, the FC-15 photoanode achieves a hydrogen production rate of 41.6 μmol/cm²/h, which is significantly improved over the unmodified sample at 5.64 μmol/cm²/h. These findings indicate that the CZTS/α-Fe₂O₃ heterojunction effectively promotes charge separation, enhances charge transport, and improves light absorption, substantially increasing photocatalytic efficiency. This heterojunction approach offers new insights and technical strategies for developing photocatalytic materials with potential applications in renewable energy. Full article

Photodetectors and gas sensors are vital in modern technology, spanning from environmental monitoring to biomedical diagnostics. This paper explores the UV detection and gas sensing properties of a zinc oxide (ZnO) nanorod array (ZNA) grown on silver nanowire mesh (AgNM) using a hydrothermal method. We examined the impact of different zinc acetate precursor concentrations on their properties. Results show the AgNM forms a network with high transparency (79%) and low sheet resistance (7.23 Ω/□). A sol–gel ZnO thin film was coated on this mesh, providing a seed layer with a hexagonal wurtzite structure. Increasing the precursor concentration alters the diameter, length, and area density of ZNAs, affecting their performance. The ZNA-AgNM-based photodetector shows enhanced dark current and photocurrent with increasing precursor concentration, achieving a maximum photoresponsivity of 114 A/W at 374 nm and a detectivity of 6.37 × 10¹⁴ Jones at 0.05 M zinc acetate. For gas sensing, the resistance of ZNA-AgNM-based sensors decreases with temperature, with the best hydrogen response (2.71) at 300 °C and 0.04 M precursor concentration. These findings highlight the potential of ZNA-AgNM for high-performance UV photodetectors and hydrogen gas sensors, offering an alternative way for the development of future sensing devices with enhanced performance and functionality. Full article

ZnO nanorod nonwoven fabrics (ZNRN) were developed through hydrothermal synthesis to facilitate the prevention of the transmission of respiratory pathogens. The superhydrophobicity and antibacterial properties of ZNRN were improved through the response surface methodology. The synthesized material exhibited significant water repellency, indicated by a water contact angle of 163.9°, and thus demonstrated antibacterial rates of 91.8% for Escherichia coli (E. coli) and 79.75% for Staphylococcus aureus (S. aureus). This indicated that E. coli with thinner peptidoglycan may be more easily killed than S. aureus. This study identified significant effects of synthesis conditions on the antibacterial effectiveness, with comprehensive multivariate analyses elucidating the underlying correlations. In addition, the ZnO nanorod structure of ZNRN was characterized through SEM and XRD analyses. It endows the properties of superhydrophobicity (thus preventing bacteria from adhering to the ZNRN surface) and antibacterial capacity (thus damaging cells through the puncturing of these nanorods). Consequently, the alignment of two such features is desired to help support the development of personal protective equipment, which assists in avoiding the spread of respiratory infections. Full article

Large-area oriented ZnO nanoarrays (including nanowire, nanorod, and nanotube) on ITO glass substrates are synthesized via the simple hydrothermal, electrodeposition, and electrochemical etching approach. The morphology of ZnO nanoarrays is controlled by adjusting the reaction temperature, reaction time, and current density. The scanning and transmission electron microscopy (SEM and TEM) results indicate the successful preparation of large-area oriented ZnO nanoarrays with different types, and the energy-dispersive X-microanalysis spectrum (EDS) and X-ray diffraction (XRD) results confirm that the composition of the obtained nanoarrays is ZnO. More importantly, the as-prepared ZnO nanotube arrays are observed with about a 40% increase in ultraviolet absorption intensity compared to the ZnO nanowire/nanorod arrays, due to having larger specific surface areas. The as-prepared different types of ZnO nanoarrays have great potential for applications in low-cost and high-performance optoelectronic devices. Full article

In this paper, we demonstrate the significant impact of the solution flow and electrical field on the homogeneity of large-scale ZnO nanorod electrodeposition from an aqueous solution containing zinc nitrate and ammonium nitrate, primarily based on the X-ray fluorescence results. The homogeneity can be enhanced by adjusting the counter electrode size and solution flow rate. We have successfully produced relatively uniform nanorod arrays on an 8 × 10 cm² i-ZnO-coated fluorine-doped tin oxide (FTO) substrate using a compact counter electrode and a vertical stirring setup. The as-grown nanorods exhibit similar surface morphologies and dominant, intense, almost uniform near-band-edge emissions in different regions of the sample. Additionally, the surface reflectance is significantly reduced after depositing the ZnO nanorods, achieving a moth-eye effect through subwavelength structuring. This effect of the nanorod array structure indicates that it can improve the utilization efficiency of light reception or emission in various optoelectronic devices and products. The large-scale preparation of ZnO nanorods is more practical to apply and has an extremely broad application value. Based on the research results, it is feasible to prepare large-scale ZnO nanorods suitable for antireflective coatings and commercial applications by optimizing the electrodeposition conditions. Full article

Zinc oxide is a promising material for the creation of various types of sensors, in particular UV detectors. In this work, arrays of ordered nanorods were grown by chemical vapor deposition. The effect of environmental humidity on the sensing properties of zinc oxide nanorod arrays was investigated, and a prototype UV sensor using indium as an ohmic contact was developed. UV photoresponses were measured for the samples stored in dry and wet atmospheres. The increase in sensitivity and response of the ZnO nanorod arrays was observed after prolonged exposure to a wet atmosphere. A model was proposed to explain this effect. This is due to the formation of hydroxyl groups on the surface of zinc oxide nanorods, which is confirmed by FTIR spectroscopy data. For the first time, it has been shown that after storage in a wet atmosphere, the sensory properties of the structure remain stable regardless of the ambient humidity. Full article

Recently, heterostructured photocatalysts have gained significant attention in the field of photocatalysis due to their superior properties compared to single photocatalysts. One of the key advantages of heterostructured photocatalysts is their ability to enhance charge separation and broaden the absorption spectrum, thereby improving photocatalytic efficiency. Zinc oxide is a widely used n-type semiconductor with a proper photoelectrochemical activity. In this study, zinc oxide nanorod arrays were synthesized, and then the surfaces of ZnO nanorods were modified with the p-type semiconductor Co₃O₄ to create a p–n junction heterostructure. A significant increase in the photocurrent for the ZnO/Co₃O₄ composite, of 4.3 times, was found compared to pure ZnO. The dependence of the photocurrent on the morphology of the ZnO/Co₃O₄ composite allows for optimization of the morphology of the ZnO nanorod array to achieve improved photoelectrochemical performance. The results showed that the ZnO/Co₃O₄ heterostructure exhibited a photocurrent density of 3.46 mA/cm², while bare ZnO demonstrated a photocurrent density of 0.8 mA/cm² at 1.23 V. The results of this study provide a better understanding of the mechanism of charge separation and transfer in the heterostructural ZnO/Co₃O₄ photocatalytic system. Furthermore, the results will be useful for the design and optimization of photocatalytic systems for water splitting and other applications. Full article

In this work, to obtain textile triboelectric layers for wearable flexible triboelectric nanogenerators (TENGs), we used two modes of growing nanostructured zinc oxide (ZnO) arrays on a carbon fabric (CF) using the automatic Successive Ionic Layer Adsorption and Reaction (SILAR) method. To produce a CF/ZnO_nr triboelectric textile with an array of intergrown short ZnO nanorods, we used a pre-coating of carbon fibers with ZnO seed layers. When the ZnO layer was fabricated by automatic SILAR on bare carbon fabric, we obtained the CF/ZnO_ns textile with an array of interconnected ZnO nanosheets 50–100 nm thick. As a proof of concept, we developed and tested two prototypes of flexible vertical contact–separation mode CF/ZnO_nr/PET/ITO and CF/ZnO_ns/PET/ITO TENGs, in which a gap was involuntarily formed between the smooth PET layer and the woven carbon textile coated with nanostructured ZnO films. In pressing tests with a force of ~5 N (pressure ~33 kPa), the CF/ZnO_ns/PET/ITO TENG created a higher open-circuit voltage up to 30 V and a higher maximum surface charge density of 1.3 μC/m². In the successive press–release tests, this TENG showed an output voltage of 3.6 V, a current density of 1.47 μA/cm², and a power density of 1.8 µW/cm², confirming its effectiveness. Full article

Bending strain sensors based on one-dimensional ZnO nanorod (NR) arrays cross-linked with interdigitated electrodes were fabricated on polyethylene terephthalate (PET) substrates. ZnO NRs were grown using the hydrothermal method through the dopings with different transition metals, such as Co, Ni, or Co-plus-Ni, on PET substrates, and their microstructural morphology and crystalline properties were examined by a variety of surface analysis methods. Ultraviolet photoresponse and normalized resistance change were measured according to the bending strains to concave and convex directions, and the highest gauge factors of 175 and 83 were achieved in the convex and concave directions, respectively, at a bending strain of 1.75%, when Co-plus-Ni was doped to the NRs. Full article

Nanostructured metal oxide semiconductors have proven to be promising for the gas sensing domain. However, there are challenges associated with the fabrication of high-performance, low-to-room-temperature operation sensors for methane and other gases, including hydrogen sulfide, carbon dioxide, and ammonia. The functional properties of these semiconducting oxides can be improved by altering the morphology, crystal size, shape, and topology. Zinc oxide (ZnO) is an attractive option for gas sensing, but the need for elevated operating temperatures has limited its practical use as a commercial gas sensor. In this work, we prepared ZnO nanorod (ZnO-NR) arrays and interconnected tetrapod ZnO (T-ZnO) network sensing platforms as chemiresistive methane sensors on silicon substrates with platinum interdigitated electrodes and systematically characterized their methane sensing response in addition to their structural and physical properties. We also conducted surface modification by photochemical-catalyzed palladium, Pd, and Pd-Ag alloy nanoparticles and compared the uniformly distributed Pd decoration versus arrayed dots. The sensing performance was assessed in terms of target gas response magnitude (RM) and response percentage (R) recorded by changes in electrical resistance upon exposure to varying methane concentration (100–10,000 ppm) under thermal (operating temperatures = 175, 200, 230 °C) and optical (UV A, 365 nm illumination) excitations alongside response/recovery times, and limit of detection quantification. Thin film sensing platforms based on T-ZnO exhibited the highest response at 200 °C (RM = 2.98; R = 66.4%) compared to ZnO-NR thin films at 230 °C (RM = 1.34; R = 25.5%), attributed to the interconnected network and effective bandgap and barrier height reduction of the T-ZnO. The Pd-Ag-catalyzed and Pd dot-catalyzed T-ZnO films had the fastest response and recovery rates at 200 °C and room temperature under UV excitation, due to the localized Pd nanoparticles dots resulting in nano Schottky barrier formation, as opposed to the films coated with uniformly distributed Pd nanoparticles. The experimental findings present morphological differences, identify various mechanistic aspects, and discern chemical pathways for methane sensing. Full article

The quality of myrrh decoction pieces can be influenced by factors such as origin, source, and processing methods. The quality of myrrh in the market varies greatly, and adulteration is a serious issue, highlighting the urgent need for improved quality control measures. This study explores the integration of GC–MS analysis and sensor selection in electronic nose technology for the improved classification of myrrh decoction pieces. GC–MS analysis revealed the presence of 130 volatile compounds in the six myrrh samples, primarily composed of alkene compounds, and each sample exhibited variations in composition. An electronic nose system was designed using a sensor array consisting of six sensors selected from twelve sensors capable of detecting volatile compounds consistent with myrrh composition, including WO₃ quantum dots, Fe₂O₃ hollow nanorods, ZnFe₂O₄ nanorods, SnO₂ nanowires, and two commercially available sensors. The sensors exhibited distinct response patterns to the myrrh samples, indicating their suitability for myrrh analysis. Various sensor parameters, including response, response and recovery time, integral area, and slope, were computed to characterize the sensors’ performance. These parameters provided valuable insight into the sensor–gas interactions and the unique chemical profiles of the myrrh samples. The LDA model demonstrated high accuracy in differentiating between the myrrh types, utilizing the discriminative features captured by the sensor array, with a classification accuracy of 90% on the testing set. This research provides a comprehensive evaluation method for the quality control of myrrh pieces and a scientific basis for the development and utilization of myrrh. Full article

One of the emerging and environmentally friendly technologies is the photoelectrochemical generation of green hydrogen; however, the cheap cost of production and the need for customizing photoelectrode properties are thought to be the main obstacles to the widespread adoption of this technology. The primary players in hydrogen production by photoelectrochemical (PEC) water splitting, which is becoming more common on a worldwide basis, are solar renewable energy and widely available metal oxide based PEC electrodes. This study attempts to prepare nanoparticulate and nanorod-arrayed films to better understand how nanomorphology can impact structural, optical, and PEC hydrogen production efficiency, as well as electrode stability. Chemical bath deposition (CBD) and spray pyrolysis are used to create ZnO nanostructured photoelectrodes. Various characterization methods are used to investigate morphologies, structures, elemental analysis, and optical characteristics. The crystallite size of the wurtzite hexagonal nanorod arrayed film was 100.8 nm for the (002) orientation, while the crystallite size of nanoparticulate ZnO was 42.1 nm for the favored (101) orientation. The lowest dislocation values for (101) nanoparticulate orientation and (002) nanorod orientation are 5.6 × 10⁻⁴ and 1.0 × 10⁻⁴ dislocation/nm², respectively. By changing the surface morphology from nanoparticulate to hexagonal nanorod arrangement, the band gap is decreased to 2.99 eV. Under white and monochromatic light irradiation, the PEC generation of H₂ is investigated using the proposed photoelectrodes. The solar-to-hydrogen conversion rate of ZnO nanorod-arrayed electrodes was 3.72% and 3.12%, respectively, under 390 and 405 nm monochromatic light, which is higher than previously reported values for other ZnO nanostructures. The output H₂ generation rates for white light and 390 nm monochromatic illuminations were 28.43 and 26.11 mmol.h⁻¹cm⁻², respectively. The nanorod-arrayed photoelectrode retains 96.6% of its original photocurrent after 10 reusability cycles, compared to 87.4% for the nanoparticulate ZnO photoelectrode. The computation of conversion efficiencies, H₂ output rates, Tafel slope, and corrosion current, as well as the application of low-cost design methods for the photoelectrodes, show how the nanorod-arrayed morphology offers low-cost, high-quality PEC performance and durability. Full article