Search Results (435)

Vertically oriented morphologies of the semiconducting metal oxide (SMO) surface provide a simple and effective means of enhancing gas sensor performance. We successfully synthesized explicitly aligned ZnO nanorods using a simple automated SILAR technique to improve acetone detection. In this work, we found that vertically oriented morphologies, such as well-aligned ZnO nanorods, can significantly enhance the sensor response due to an increase in specific active area and electron mobility, allowing a faster response to changes in the gas environment. The optimal operating temperature for our ZnO nanorod-based sensors in detecting acetone gas is 260 °C. At this temperature, the sensors exhibit a 96% response with a rapid response time of just 3 s. The improved sensing performance is attributed to both electronic and chemical sensitization mechanisms, which enhance the formation of active sites and shorten electron diffusion paths. Full article

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

A strong interaction between Bi³⁺ and ZnO was used to successfully sensitize ZnO nanorods with quantum dots (QDs) of Bi₂O₃ through three different strategies. Although the Bi₂O₃ QDs had similar particle size distributions, their photocatalytic performance varied significantly, prompting the investigation of factors beyond particle size. The study revealed that the photochemical method selectively deposited Bi₂O₃ QDs onto electron-rich ZnO sites, providing a favorable pathway for efficient electron–hole separation and transfer. Consequently, abundant h⁺ and ·OH radicals were generated, which effectively degraded Rhodamine B (RhB). As demonstrated in the RhB degradation experiments, the Bi₂O₃/ZnO nanorod catalyst achieved an 89.3% degradation rate within 120 min, significantly outperforming catalysts with other morphologies. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) results indicated that the Bi₂O₃/ZnO heterostructure constructed an effective interface to facilitate the spatial separation of photogenerated charge carriers, which effectively prolonged their lifetime. The electron paramagnetic resonance (EPR) results confirmed that the ·OH radicals played a key role in the degradation process. Full article

This study investigates the effects of substrate flexibility and metal deposition methods on piezoelectric-enhanced Surface-Enhanced Raman Scattering (SERS) in metal-deposited ZnO nanorod (NR) nanocomposites (NCPs). ZnO NRs were grown on both rigid (ITO–glass) and flexible (ITO-PET) substrates, followed by gold (Au) deposition by pulsed-laser-induced photolysis (PLIP) or silver (Ag) deposition by thermal evaporation. Structural analysis revealed that ZnO NRs on flexible substrates exhibited smaller diameters (60–80 nm vs. 80–100 nm on glass), a higher density, and diverse orientations that enhanced piezoelectric responsiveness. Optical characterization showed distinct localized surface plasmon resonance (LSPR) peaks at 420 nm for Ag and 525 nm for Au systems. SERS measurements demonstrated that Ag-ZnO NCPs achieved superior detection limits (10⁻⁹ M R6G) with enhancement factors of 10⁸–10⁹, while Au-ZnO NCPs reached 10⁻⁸ M detection limits. Mechanical bending of flexible substrates induced dramatic signal enhancement (50–100-fold for Au-ZnO/PET and 2–3-fold for Ag-ZnO/PET), directly confirming piezoelectric enhancement mechanisms. This work establishes quantitative structure–property relationships in piezoelectric-enhanced SERS and provides design principles for high-performance flexible sensors. 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

ZnO nanorods are promising nanomaterials for photoelectrochemical photodetectors (PEC PDs). However, the weak photocurrent density, delayed response, and low stability of ZnO are major drawbacks for their applications. To address these challenges, we integrated multilayer MoS₂ nanosheets with ZnO nanorods using a chemical bath deposition method. The resulting ZnO/MoS₂ heterojunction achieved a photocurrent density of 1.02 mA/cm² (~20 times higher than that of bare ZnO), ultrafast response times (90/150 ms), and 92% stability retention over 3600 s. These enhancements originated from suppressed charge recombination and accelerated water oxidation kinetics. Our work provides another possible energy-saving route toward developing high-efficiency and stable ZnO-based photoanodes for practical applications in PEC PDs. Full article

In the first part of this study, Y₂O₃-doped copper thiocyanate (CuSCN) with different x wt% (named CuSCN-xY, x = 0, 1, 2, and 3) films were synthesized onto ITO substrates using the spin coating method. UV-vis, SEM, AFM, EDS, and cyclic voltammetry were used to investigate the material properties of the proposed films. The conductivity and carrier mobility of the films increased with additional yttrium doping. It was found that the films with 2% Y₂O₃ (CuSCN-2Y) have the smallest valence band edges (5.28 eV). Meanwhile, CuSCN-2Y films demonstrated the densest surface morphology and the smallest surface roughness (22.8 nm), along with the highest conductivity value of 764 S cm⁻¹. Then, P-I-N self-powered UV photodetectors (PDs) were fabricated using the ITO substrate/ZnO seed layer/ZnO nanorod/CsPbBr₃/CuSCN-xY/Ag structure, and the characteristics of the devices were measured. In terms of response time, the rise time and fall time were reduced from 26 ms/22 ms to 9 ms/5 ms; the responsivity was increased from 243 mA/W to 534 mA/W, and the on/off ratio was increased to 2.47 × 10⁶. The results showed that Y₂O₃ doping also helped improve the P-I-N photodetector’s device performance, and the mechanisms were investigated. Compared with other published P-I-N self-powered photodetectors, our proposed devices show a fairly high on/off ratio, quick response times, and high responsivity and detectivity. Full article

Molybdenum disulfide (MoS₂) has gained attention for its promising gas-sensing capabilities due to its high surface area and tunable electronic properties. In this study, we investigate the time-dependent growth (under constant conditions) of sputtered MoS₂ films on ZnO nanorods and their impact on NO₂ sensing performance. ZnO nanorods, synthesized via a hydrothermal method, provide a high-surface-area template to enhance charge transport and gas adsorption. Gas-sensing experiments revealed a strong correlation between MoS₂ thickness and NO₂ response, with the 25-min-sputtered MoS₂ film exhibiting the highest response of 20.9%. The synergistic interaction between MoS₂ and ZnO nanorods facilitated charge transfer and enhanced adsorption sites for NO₂ molecules. These findings emphasize the critical role of time-dependent growth of MoS₂ film in modulating gas-sensing performance and provide insights into designing high-sensitivity NO₂ sensors at room temperature. This study contributes to the development of hybrid MoS₂/ZnO nanostructures for next-generation environmental monitoring applications. Full article

The currently used electrical energy devices for portable applications are in limited life and need of frequent recharging, it is a big bottleneck for wireless and transportation systems. The scientific community is motivated to find innovative and efficient devices to convert environmental energy into useful forms. Nanogenerator can mitigate this issue by harvesting ambient energy of different forms into useful electrical energy. Particularly flexible nanogenerators can efficiently convert ambient mechanical energy into electrical energy which can be fruitfully used for self-powered sensors and electronic appliances. Zinc oxide is an interesting photosensitive and piezoelectric material that is expected to play a vital role in the synergetic harvesting of environmental thermal, sound, mechanical, and solar energies. As ZnO can be synthesized using easy methods and materials at low cost, the conversion efficiencies of solar and other energy forms can increase considerably. ZnO is a versatile material with interesting semiconducting, optical, and piezoelectric properties; it can be used advantageously to harvest more than one type of ambient energy. The coupled semiconducting and piezoelectric properties of ZnO are attractive for fabricating nanogenerators capable of harvesting both ambient optical and mechanical energies simultaneously. These nanolevel conversion devices are much required to power remote and implantable devices without the need for additional power sources. The present review briefly discusses the principles and mechanisms of different energy harvesting abilities of ZnO nanorods and their composites by consolidating available literature. In addition, the developments taking place in nanogenerators of different kinds—such as photovoltaic, piezoelectric, pyroelectric, and triboelectrics for self-powered technology—and their progress in hybrid energy harvesting application is reviewed. Full article

The enduring problem of CO₂ emissions and their consequent influence on the earth’s atmosphere has captured the attention of researchers. Photocatalytic CO₂ reduction holds great significance; however, it is constrained by the effect of carrier recombination. Simultaneously, the structural modification of heterojunction catalysts has emerged as a promising approach to boost the photocatalytic performance. Herein, Zn₂GeO₄@CeO₂ core@shell nanorods were prepared by a simple self-assembly method for photocatalytic CO₂ reduction. The thickness of the CeO₂ shell can be regulated rapidly and conveniently. The photocatalytic results indicate that the structure regulation could affect the photocatalytic performance by controlling the amount of active sites and the shielding effect. X-ray photoelectron spectroscopy (XPS) and Mott–Schottky analyses reveal that Zn₂GeO₄ and CeO₂ formed Type-I heterojunctions, which prolonged the lifetime of the photogenerated carriers. The CO₂ adsorption and activation capacities of CeO₂ also exert a beneficial influence on the progress of CO₂ photoreduction, thus enabling efficient photocatalytic CO₂ reduction. Moreover, the in situ FT-IR spectra show that Zn₂GeO₄@CeO₂ suppresses the formation of byproduct intermediates and shows higher CO selectivity. The best sample of Zn₂GeO₄@0.07CeO₂ can exhibit a CO yield of as high as 1190.9 μmol g⁻¹ h⁻¹. Full article

This study presents the development of a zinc oxide (ZnO) nanorod-based sensor for the detection and quantification of residual pesticides commonly found in tea plantations, with a focus on quinalphos and thiamethoxam. Exploiting the unique electrical characteristics of ZnO nanorods, the sensor exhibits high sensitivity and selectivity in monitoring trace levels of pesticide residues. The detection mechanism relies on measurable changes in electrical resistance when the ZnO nanorod-coated electrodes interact with varying concentrations of the target pesticides. A performance evaluation was carried out using water samples spiked with different pesticide concentrations. The sensor displayed distinct response profiles for each compound: a linear resistance–concentration relationship for quinalphos and a non-linear, saturating trend for thiamethoxam, reflecting their differential interactions with the ZnO surface. Statistical analysis confirmed the sensor’s reliability, reproducibility, and consistency across repeated measurements. The rapid response time and ease of fabrication underscore its potential for real-time, on-site pesticide monitoring. This method offers a promising alternative to traditional analytical techniques, enhancing food safety assurance and supporting sustainable agricultural practices through effective environmental surveillance. Full article

In the context of the global energy transition, enhancing the efficiency of polycrystalline silicon-based solar cells remains a critical research priority. This study investigates the integration of ZnO-based nanostructured layers. ZnO and Al-doped ZnO nanoparticles, synthesized via hydrothermal methods and concentrated solar power (CSP) vapor condensation, exhibiting diverse morphologies—nanorods, spheres, and whisker structures—were deposited onto commercial solar cells using the spin coating technique. Structural, morphological, and spectroscopic analyses confirmed the formation of crystalline layers with high active surface areas and controlled morphology. Photovoltaic performance was assessed using a dedicated hardware–software system under real sunlight conditions. The results demonstrate a significant increase in energy efficiency, reaching up to 10.97%, compared with 1.51% for polycrystalline silicon cells without any supplementary layers. This improvement is attributed to enhanced light absorption, reduced carrier recombination, and more efficient charge transport, driven by nanoscale design and doping. This study underscores the importance of sustainable synthesis and morphological control in the development of high-performance and cost-effective solar technologies. Full article

Hybrid nanostructures can be engineered to exhibit superior functionality beyond the level attainable from each of the constituent nanomaterials by synergistically integrating their unique properties. In this work, we designed individual hybrid nanorods (NRs) of ZnO–Ag in different heterojunction configurations where each hybrid NR consists of a single ZnO NR forming a junction with a single Ag NR. We subsequently employed the ZnO–Ag hybrid NRs in the fluorescence detection of the model chemical and biological analytes, rhodamine 6G (R6G), and tumor necrosis factor-α (TNF-α), that undergo simple as well as more complex immunoreaction steps on the hybrid NRs. We determine how parameters such as the analyte concentration, ZnO–Ag heterojunction configuration, and NR length can influence the fluorescence signals, enhancement factors (EFs), as well as changes in EFs (%EFs) at different positions on the hybrid NRs. We provide much needed insights into the fluorescence enhancement capability of single hybrid NR systems using a signal source located external to the NRs. Moreover, we identify key consideration factors that are critical to the design and optimization of a hybrid NR platform for achieving high signal enhancements. We show that higher EFs are consistently observed from the junction relative to other positions in a given hybrid NR, from the end–end relative to other heterojunction configurations, and from longer than shorter ZnO NRs. Our research efforts demonstrate that the synergistic interplay of the two component NRs of ZnO and Ag escalates the fluorescence detection capability of the ZnO–Ag hybrid NR. A superior enhancement level surpassing those attainable by each component NR alone can be obtained from the hybrid NR. Hence, our work further substantiates the potential utility of individual semiconductor-metal hybrid NRs for highly miniaturized and ultra-trace level detection, especially by leveraging the critical consideration factors to achieve a higher 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

Discrete Dipole Approximation (DDA) is a rapidly developing numerical method in recent years. DDA has found wide application in many research fields including plasmonics and atmospheric optics. Currently, few DDA packages based on Python have been reported. In this work, a Python package called CPDDA is developed. It can be used to simulate the light-scattering and -absorption properties of arbitrarily shaped particles. CPDDA uses object-oriented programming, offers high flexibility and extensibility, and provides a comprehensive database of refractive indices. The package uses the biconjugate gradient method and fast Fourier transform for program acceleration and memory optimization, and it uses parallel computation with graphics processing units to enhance program performance. The accuracy and performance of CPDDA were demonstrated by comparison with Mie theory, the MATLAB package MPDDA, and the Python package pyGDM2. Finally, CPDDA was used to simulate the variations in light-absorption and -scattering properties of ZnO@Au core-shell nanorods based on the particle size. CPDDA is useful for calculating light-scattering and -absorption properties of small particles and selecting materials with excellent optical properties. Full article