Synthesis and Characterization of Zinc Oxide (ZnO) Nanowire (original) (raw)
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Comparative study on the properties of ZnO nanowires and nanocrystalline thin films
Surface and Coatings Technology, 2012
The microstructural, morphological, optical and water-adsorption properties of nanocrystalline ZnO thin films and ZnO nanowires were studied and compared. The ZnO thin films were obtained by a sol-gel process, while the ZnO nanowires were electrochemically grown onto a ZnO sol-gel spin-coated seed layer. Thin films and nanowires samples were deposited onto crystalline quartz substrates covered by an Au electrode, able to be used in a quartz crystal microbalance. X-ray diffraction measurements reveal in both cases a typical diffraction pattern of ZnO wurtzite structure. Scanning electron microscopic images of nanowires samples show the presence of nanowires with hexagonal sections, with diameters ranging from 30 to 90 nm. Optical characterization reveals a bandgap energy of 3.29 eV for the nanowires and 3.35 eV for the thin films. A quartz crystal microbalance placed in a vacuum chamber was used to quantify the amount and kinetics of water adsorption onto the samples. Nanowire samples, which have higher surface areas than the thin films, adsorb significantly more water.
Journal of Nanoengineering and Nanomanufacturing, 2012
Crystalline hexagonal wurtzite nanowires of ZnO were prepared by thermal evaporation method from zinc foil with zinc microparticles in air atmosphere. The nanowires have been characterized by a scanning electron microscope (SEM), a scanning transmission electron microscope (STEM), energy dispersive X-ray spectrometer (EDS), Raman spectroscopy, UV-Vis absorption and room temperature photoluminescence (PL). SEM and STEM images show that as-obtained ZnO nanowires have diameters in the range between 40 nm and 60 nm and length up to 30 m. The Raman spectrum of the ZnO nanowires were obtained and compared with the corresponding spectrum of the bulk ZnO. The optical band gap is found to be 3.34 eV. PL measurements show that the nanowires present a strong UV emission peak at 487 nm (2.54 eV) accompanied by other peaks of relatively lower intensities. This emission is due to the existence of various defects in the fabricated nanowires. These nanowires have potential in applications such as optoelectronics.
Applied Physics A, 2020
In this study, zinc oxide nanowires are elaborated by the hydrothermal method using a microwave furnace, which varies power and deposition times. The growth of nanowires is done on a buffer layer deposited on glass substrates using the sol-gel method associated with spin-coating. The X-Ray Diffraction (XRD) spectrums indicate that the obtained nanowires are well oriented in (002) plane according to the hexagonal wurtzite phase. The density and length of these nanowires increase while their diameter decreases with the deposition time and the microwave power. For high powers and longer deposition times, the ZnO nanowires adopt a pyramidal shape due to the low concentration of OH − hydroxides in the deposition solution. The elaborated nanowires have an optical transmittance level in the visible region of about 90% with a red shift of the optical gap as the deposition time increases qualifying them for photovoltaic and other optoelectronic applications. A correlation between the diameter of the nanowires and their optical gap has been found which illustrates the narrow relationship between the structural, electronic, and optical aspects of these nanowires.
Effects of Deposition Parameters of Hydrothermal Method on Synthesis of ZnO-based Nanowires
Sensors and Materials, 2019
(NO 3) 2 ‧6H 2 O, ZnO-based nanowires, growth time ZnO-based nanomaterials can be used as sensors for different applications, including gas and ultraviolet (UV) ray sensors. To grow ZnO nanowires by the hydrothermal method, a ZnO seed layer was prepared by a sputtering method to deposit ZnO films on SiO 2 /Si substrates of about 200 nm thickness. Next, Zn(NO 3) 2 ‧6H 2 O and C 6 H 12 N 4 were used as reagents, and DI water was used as a solvent, and they were mixed to the designed compositions. We found that when Zn(NO 3) 2 ‧6H 2 O and C 6 H 12 N 4 were used as reagents to grow ZnO nanostructured materials, growth temperature, the concentration of the diluted solution, growth time, and the position of the substrates were four important factors affecting the synthesis results. The surface morphologies of ZnO nanowires were observed by field-emission scanning electron microscopy (FESEM), and crystalline phases were analyzed using X-ray diffraction (XRD) patterns. The FESEM images and XRD patterns were used to determine the effects of synthesis parameters on the morphologies and crystalline properties of the grown nanostructured materials. First, we found that 100 ℃ was the optimum synthesis temperature for growing pure ZnO nanowires, because ZnO-based nanowires could be successfully synthesized at different concentrations of Zn(NO 3) 2 ‧6H 2 O and C 6 H 12 N 4 and different synthesis times. The effects of growth time, the position of the substrates on the carry sheet glass, and concentrations of Zn(NO 3) 2 ‧6H 2 O and C 6 H 12 N 4 on the growth of nanostructured materials were also investigated.
Synthesis, Characterization, and Applications of ZnO Nanowires
ZnO nanowires (or nanorods) have been widely studied due to their unique material properties and remarkable performance in electronics, optics, and photonics. Recently, photocatalytic applications of ZnO nanowires are of increased interest in environmental protection applications. This paper presents a review of the current research of ZnO nanowires (or nanorods) with special focus on photocatalysis. We have reviewed the semiconducting photocatalysts and discussed a variety of synthesis methods of ZnO nanowires and their corresponding effectiveness in photocatalysis. We have also presented the characterization of ZnO nanowires from the literature and from our own measurements. Finally, a wide range of uses of ZnO nanowires in various applications is highlighted in this paper.
Synthesis and Photoluminescence Studies on Zinc Oxide Nanowires
ASEAN Journal on Science and Technology for Development, 2017
Semiconductor single crystal ZnO nanowires have been successfully synthesized by a simple method based on thermal evaporation of ZnO powders mixed with graphite. Metallic catalysts, carrying gases, and vacuum conditions are not necessary. The x-ray diffraction (XRD) analysis shows that the ZnO nanowires are highly crystallized and have a typical wurtzite hexagonal structure with lattice constants a = 0.3246 nm and c = 0.5203 nm. The scanning electron microscopy (SEM) images of nanowires indicate that diameters of the ZnO nanowires normally range from 100 to 300 nm and their lengths are several tens of micrometers. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra of the nanowires were measured in the range of temperature from 15 K to the room temperature. Photoluminescence spectra at low temperatures exhibit a group of ultraviolet (UV) narrow peaks in the region 368 nm ~ 390 nm, and a blue-green very broad peak at 500 nm. Origin of the emission lines in PL spectr...
ZINC OXIDE NANOWIRES SYNTHESIZED BY THERMAL EVAPORATION METHOD WITH AND WITHOUT CATALYST
The fabrication of zinc oxide nanowires and their characterization are presented in this paper. Gold catalyst was employed on certain set of experiments. The sample were fabricated within a horizontal quartz tube under controlled supply of O2 and Ar gases and heated at 700 o C up to 1200 o C. Initially, the tube was evacuated around 1 torr using a mechanical pump and the gas is allowed to pass at a known flow rate so that the evaporated source will be driven to the Silicon substrate. The substrate was previously cleaned and deposited with gold nanoparticles using a dipping process to act as a catalyst during vapor-liquid-solid mechanism. Another set of samples was prepared without the aid of gold catalyst and the process involved is called selfcatalytic growth. The structural morphology of both catalyst and catalyst-free samples was characterized using scanning electron microscopy and field emission scanning electron microscopy, whilst the field emission properties of the nanowires were measured using photoluminescence spectroscopy at room temperature. Both SEM and FESEM results showed that the optimal conditions for the growth of ZnO nanowires with gold catalyst were identified as follows: 90 mins growth time and gas flow rate ranging from 1.1 to 5.0 sccm. High aspect ratio of around 10.5 and low surface density were also observed. Catalyst-free ZnO:Al nanowires showed a randomly orientated nanowires with varying nanostructures as the dopant concentrations were increased from 0 to 2.4 at%. Interesting features were observed at 2.4 at%, shown by a perfect hexagonal similar to 'pencil-like' shape. This was further analysed by EDX which confirmed an optimal level of dopant concentration for the synthesis of ZnO:Al nanorods. The measured diameters were roughly between 260 to 350 nm and the length about 720 nm. From The results showed the importance of Al doping that played an important role on the morphology of ZnO nanostructures. This may led to potential applications in sensor and biological applications.
Formation and characterization of zinc oxide nanowires grown on hexagonal-prism microstructures
Materials Letters, 2011
In this paper, zinc oxide (ZnO) micro-and nano-structures were synthesized through a chemical vapor deposition route. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), and scanning electron microscopy (SEM) were used to study the samples' phase, composition, purity, and structure. XRD analysis confirmed the formation of the wurtzite phase in all samples. SEM images revealed the formation of hexagonal-prism microstructures of ZnO. After we changed the conditions, nano-wires 40-50 nm in diameter appeared on these hexagonal-prism microstructures. Further, we investigated the photoluminescence properties of these structures at room temperature. The modified structures showed UV emission and strong blue-green photoluminescence line due to near-band emission and oxygen vacancies respectively.
World Journal of Nano Science and Engineering, 2015
Zinc oxide (ZnO) nanorods have been synthesized by solution processing hydrothermal method in low temperature using the spin coating technique. Zinc acetate dehydrate, Zinc nitrate hexahydrate and hexamethylenetetramine were used as a starting material. The ZnO seed layer was first deposited by spin coated of ethanol zinc acetate dehydrate solution on a glass substrate. ZnO nanorods were grown on the ZnO seed layer from zinc nitrate hexahydrate and hexamethylenetetramine solution, and their diameters, lengths were controlled by precursor concentration and development time. From UV-Visible spectrometry the optical band gap energy of ZnO nanorods was calculated to be 3.3 eV. The results of X-Ray Diffraction (XRD) showed the highly oriented nature of ZnO nanorods the hardest (002) peak reflects that c-axis elongated nanorods are oriented normal to the glass substrate. The Field Emission Scanning Electron Microscope (FESEM) was employed to measure both of average diameter of ZnO nanorods, Energy Dispersive X-Ray (EDX) is used to identify the elemental present and to determine the element composition in the samples.