Zinc Oxide Nanowhiskers Research Articles

Exploring the antibacterial and dermatitis-mitigating properties of chicken egg white-synthesized zinc oxide nano whiskers.

Zinc oxide nanoparticles (ZnO-NPs) have garnered considerable interest in biomedical research primarily owing to their prospective therapeutic implications in combatting pathogenic diseases and microbial infections. The primary objective of this study was to examine the biosynthesis of zinc oxide nanowhiskers (ZnO-NWs) using chicken egg white (albumin) as a bio-template. Furthermore, this study aimed to explore the potential biomedical applications of ZnO NWs in the context of infectious diseases. The NWs synthesized through biological processes were observed using electron microscopy, which allowed for detailed examination of their characteristics. The results of these investigations indicated that the NWs exhibited a size distribution ranging from approximately 10 to 100 nm. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) mapping analyses successfully corroborated the size, dimensions, and presence of biological constituents during their formation. In this study, XTT assay and confocal imaging were employed to provide evidence of the efficacy of ZnO-NWs in the eradication of bacterial biofilms. The target bacterial strains were Staphylococcus aureus and Escherichia coli. Furthermore, we sought to address pertinent concerns regarding the biocompatibility of the ZnO-NWs. This was achieved through comprehensive evaluation of the absence of cytotoxicity in normal HEK-293T and erythrocytes. The findings of this investigation unequivocally confirmed the biocompatibility of the ZnO-NWs. The biosynthesized ZnO-NWs demonstrated a noteworthy capacity to mitigate the dermatitis-induced consequences induced by Staphylococcus aureus in murine models after a therapeutic intervention lasting for one week. This study presents a comprehensive examination of the biosynthesis of zinc oxide nanowhiskers (ZnO-NWs) derived from chicken egg whites. These findings highlight the considerable potential of biosynthesized ZnO-NWs as a viable option for the development of therapeutic agents targeting infectious diseases. The antibacterial efficacy of ZnO-NWs against both susceptible and antibiotic-resistant bacterial strains, as well as their ability to eradicate biofilms, suggests their promising role in combating infectious diseases. Furthermore, the confirmed biocompatibility of ZnO-NWs opens avenues for their safe use in biomedical applications. Overall, this research underscores the therapeutic promise of ZnO-NWs and their potential significance in future biomedical advancements.

Low-Temperature Vapor-Solid Growth of ZnO Nanowhiskers for Electron Field Emission

One-dimensional zinc oxide nanostructures have aroused interest from scientists and engineers for electron field emission applications because of their experimentally accessible high aspect ratio in combination with their low work function. A comprehensive study of the vapor-solid growth of zinc oxide (ZnO) nanowhiskers by utilizing zinc acetylacetonate hydrate and oxygen at low temperature (580 °C) is reported herein. The nanowhiskers morphology was investigated by varying different growth parameters, such as temperature, substrate type and position, gas flow, precursor amount, and growth time. According to the obtained parameter dependences, the process was optimized to achieve homogenous crystalline nanowhiskers with high aspect ratios and clearly defined surface facets and tips. We show electron field emission measurements from tailor-made ZnO nanowhiskers grown on n-doped silicon, titanium thin films, and free-standing silicon nitride membranes, revealing field emission turn-on fields significantly lower compared to a perfect flat ZnO thin film. Especially the latter devices—ZnO nanowhiskers on a free-standing membrane—might pave the way into a novel nanomembrane detector unit in proteomics, which can significantly extend the mass range of current time-of-flight mass spectrometers.

Potential of zinc oxide nanowhiskers as antireflection coating in crystalline silicon solar cell for cost effectiveness

Antireflection coatings play an important role in enhancing the performance of crystalline silicon solar cells by increasing the light coupling into the active region of the devices. In this work we investigated the effects of seed layer thickness and growth time on the reflection properties of solution-grown zinc oxide nanowhiskers. Our results reveal the potential of zinc oxide nanowhiskers as antireflection coating in crystalline silicon solar cells as investigated herein. With this efficient antireflection coating, we have presented a hierarchical structure integrating zinc oxide nanowhisker arrays on silicon micropyramids for improving the energy conversion efficiency. This structure displays broadband reflection suppression in the 300–1200 nm range, with an integrated reflectance of 2.28%. A conversion efficiency of 13.3% was obtained, which is significantly high for large area (3″ × 3″) solar cell fabricated using zinc oxide nanowhiskers as the antireflection coating layer.

Methane Gas Sensing Properties of the Zinc Oxide Nanowhisker-derived Gas Sensor

A low power methane gas sensor with microheater was fabricated by silicon bulk micromachining technology. In order to heat up the sensing layer to operating temperature, a platinum (Pt) micro heater was embedded in the gas sensor. The line width and gap of the microheater was 20 <TEX>${\mu}m$</TEX> and 4.5 <TEX>${\mu}m$</TEX>, respectively. Zinc oxide (ZnO) nanowhisker arrays were grown on a sensor from a ZnO seed layer using a hydrothermal method. A 200 ml aqueous solution of 0.1 mol zinc nitrate hexahydrate, 0.1 mol hexamethylenetetramine, and 0.02 mol polyethylenimine was used for growing ZnO nanowhiskers. Temperature distribution of the sensor was analyzed by infrared thermal camera. The optimum temperature for highest sensitivity was found to be <TEX>$250^{\circ}C$</TEX> although relatively high (64%) sensitivity was obtained even at as low a temperature as <TEX>$150^{\circ}C$</TEX>. The power consumption was 72 mW at <TEX>$250^{\circ}C$</TEX>, and only 25 mW at <TEX>$150^{\circ}C$</TEX>.

Acoustic emission based flexural characteristics of glass fiber reinforced composites embedded with ZnO nanowhiskers

In recent years, Zinc oxide (ZnO) nanowhiskers, with good functional and mechanical properties, have been used for the preparation of structural and functional composites. However, the reinforcement mechanism of ZnO nanowhiskers in the composites is not fully understood. In this study, three-point bend tests have been carried out to investigate the flexural properties of the composites which contain different amounts of ZnO nanowhiskers. To obtain the reinforcement mechanism of ZnO nanowhiskers, acoustic emission (AE) technique was applied to evaluate the characteristics of the damage progress and the failure mechanism of the specimens. In addition, linear AE source location was also performed to monitor the damage initiation and propagation. The presence of ZnO nanowhiskers in the resin matrix influences the flexural strength and corresponding AE signals during the fracture process of the specimens. The results show that the composites embedded with 15 wt% ZnO nanowhiskers in the resin exhibit the highest flexural strength, AE energy, counts, and the longest duration and also hits of AE source location.

Effects of ZnO Nanowhiskers Addition on Microstructure and Dielectric Properties of Lead Titanate Ceramics

Ceramic nanocomposites of zinc oxide (ZnO) nanowhiskers in lead titanate (PbTiO3 or PT) matrix were successfully fabricated by a pressureless sintering technique. Phase formation, densification, microstructure and dielectric properties of the composites were investigated as a function of ZnO content. It has been found that a densification of the ceramic nanocomposites fabricated in this work was significantly enhanced, as compared to the conventional PT ceramics. Moreover, the high dielectric constant, which is higher than that of the monolithic PT ceramics, was found in the PT/ZnO ceramic nanocomposites.

Dynamic compressive response and failure behavior of fiber polymer composites embedded with tetra-needle-like ZnO nanowhiskers

Glass fiber polymer composites embedded with tetra-needle-like zinc oxide (ZnO) nanowhiskers were prepared. The prepared composites exhibited excellent mechanical properties after the effective dispersion of ZnO nanowhiskers in the resin. The static and dynamic compressive properties of the composites were tested in the thickness and in-plane directions. The macro- and microfracture morphologies of the damaged specimens were obtained by using a scanning electron microscope. The results show that the compressive properties of the composites could be significantly affected by strain rates. As the strain rate increases, the composites have a higher strength. The compressive properties of the composites are affected by the content of ZnO nanowhiskers in the resin. The high strength of the composites can be attributed to the three-dimensional structures of ZnO nanowhiskers and the corresponding stress transfer.

Thickness effect on electrical properties of Pb(Zr 0.52Ti 0.48)O 3 thick films embedded with ZnO nanowhiskers prepared by a hybrid sol–gel route

Silicon-based lead zirconate titanate thick films embedded with zinc oxide nanowhiskers (ZnO w–PZT) were prepared by a hybrid sol–gel route. ZnO w–PZT films with thickness from 1.5 μm to 4 μm are perovskite structure and have smooth surface without any cracks. As the thickness increases, the remanent polarization and dielectric constant increase, but the coercive field and tetragonality decrease. Compared with PZT films, the ZnO w–PZT film has the close tetragonality and electrical properties which are different from those of bulk PZT-based ceramic doped with ZnO powder. The thickness dependences of the ferroelectric and dielectric properties are attributed to the relaxation of internal stress.

Characterizations of Ag-catalyzed ZnO nanostructures prepared by vapor–solid mechanism

This paper presents the synthesis and field emission characteristics of zinc oxide (ZnO) nanostructures grown on Ag-deposited Si substrate by using the vapor–solid (VS) mechanism. The morphology of the ZnO nanostructures was related to source and substrate temperatures. Nanowhiskers, nanotips and well-aligned nanorods were grown at substrate temperatures of 620, 650 and 680 °C, respectively. A strong bluish-green photoluminescence (PL) indicated that the nanostructures had many surface defects correlated with oxygen vacancies. Field emission analyses showed that the turn-on fields of ZnO nanowhiskers, nanotips and well-aligned nanorods were 4.5, 5.8 and 6.1 V/μm, respectively. The high emitter density and high aspect ratio of the well-aligned nanorods resulted in an enhancement in emission current density. Furthermore, the field emission stability of the well-aligned nanorods was better than that of the nanowhiskers and nanotips. The emission current densities of the ZnO nanowhiskers, nanotips and well-aligned nanorods, measured after continuous operation for 6 h, were approximately 2.05, 4.68 and 20.5 μA/cm 2, respectively.

Enhanced mechanical behaviour of lead zirconate titanate piezoelectric composites incorporating zinc oxide nanowhiskers

This paper reports that the lead zirconate titanate (PZT) piezoelectric composites incorporating zinc oxide nanowhiskers (ZnOw) were prepared by the conventional solid state processing. The whisker-dispersed PZT composites (PZT/ZnOw) presented a significant enhancement in the mechanical properties such as Young's modulus, tensile strength and compressive strength. Especially, the compressive strength increased from 153 MPa for the PZT to 228 MPa for the PZT/ZnOw composites. The reinforcement mechanism in strength of the composites was discussed. The mechanical quality factors of the PZT/ZnOw composites increased considerably, while the piezoelectric constants and electromechanical coupling coefficient decreased slightly. The composites with good electrical and excellent mechanical properties are promising for further applications.

Fabrication and field emission properties of regular hexagonal flowerlike ZnO nanowhiskers

Regular hexagonal flowerlike zinc oxide (ZnO) whiskers have been fabricated on the indium tin oxide electrodes with glass panel. A relatively simple hydrothermal growth process of low temperature is developed. The field emission properties of the flowerlike ZnO nanowhiskers have a low field emission threshold voltage (2.2V∕μm at a current density of 0.1μA∕cm2) and a high current density of 1mA∕cm2 at an applied field of 6.3V∕μm. The hydrothermal process method and good field emission properties indicate their potential application in field emission display device with glass panels.

Growth of zinc oxide nanostructures

Zinc oxide (ZnO) nanowhiskers have been prepared using a multilayer ZnO(50 nm)/Zn(20 nm)/ZnO(2μm) structure on a polished stainless steel (SS) substrate by high rate magnetron sputtering. The formation of uniformly distributed ZnO nanowhiskers with about 20 nm dia. and 2 to 5 μm length was observed after a postdeposition annealing of the prepared structure at 300–400° C. An array of highlyc-axis oriented ZnO columns (70–300 nm in dia. and up to 10 μm long) were grown on Si substrates by pulsed laser deposition (PLD) at a high pressure (1 Torr), and Raman studies showed the activation of surface phonon modes. The nanosized powder (15–20 nm) and nanoparticle ZnO films on glass substrate were also prepared by a chemical route. Nanowhiskers showed enhanced UV light detection characteristics, and the chemically prepared ZnO nanoparticle films exhibited good sensing properties for alcohol

Multipod zinc oxide nanowhiskers

Zinc oxide nanowhiskers with multipod structures have been fabricated on copper-coated Si wafer by sintering the mixture of ZnO and graphite powders in air. The multipod nanowhisker shows tetrapod, tripod and hexapod morphologies with legs of 100–500 nm in diameter and several microns in length. The legs of the multipod nanowhisker intercross at a central knot of the whisker. The octahedron twin nucleus is responsible for the tetrapod structure and possibly responsible for the tripod structure as well. The hexapod structure is due to a stacked nucleus of two octahedron nuclei.

Synthesis of ZnO nanowhiskers by a simple method

By means of a novel and simple method, zinc oxide (ZnO) nanowhiskers, which the diameters are about 15–30 nm and the lengths are up to 100 nm, are synthesized in the presence of a nonionic surfactant (Polyethylene glycol 400). The products are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM). These nanowhiskers have fine crystal structure. The surfactant is used to control the sizes of ZnO particles in precursor.