Morphology Of ZnO Nanoparticles Research Articles

Effect of Aqueous Ablation Environment on the Characteristics of ZnO Nanoparticles Produced by Laser Ablation

Effect of ablation environment on the nature of ZnO nanoparticles produced by laser ablation method in liquid medium is investigated experimentally. High purity Zn plate was irradiated by the fundamental beam of a Q-switch Nd-YAG laser in cetyltrimethylammonium bromide (CTAB), acetone, sodium dodecyl sulfate and water. Produced nanoparticles were characterized by UV–Vis absorption spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction spectrum, and fourier transform infrared spectroscopy. Results show that the highest rate of ablation occurs in CTAB. Largest nanoparticles are produced in acetone, and crystallinity of nanoparticles produced in CTAB is higher than other samples. CTAB surfactant changed the morphology of ZnO nanoparticles.

Synthesis and characterization of Mn-doped ZnO diluted magnetic semiconductors

In the present work undoped and Mn doped ZnO nanoparticles (ZnO:Mn), diluted magnetic semiconductors, were successfully synthesized by the sol–gel method at room temperature. The morphology of ZnO nanoparticles constituted by flower-like structures with hexagonal morphologies that changed significantly after the incorporation of Mn. Rietveld refinements results showed that Mn ions are successfully doped into ZnO matrix without altering its wurtzite phase. Meanwhile, Raman spectroscopy analyses confirm the wurtzite structure of undoped ZnO and ZnO:Mn nanoparticles. The lattice parameters increase with increasing Mn content due to the large ionic radius of Mn2+ compared to that of Zn2+. Electron spin resonance measurements were performed to gain information about oxidation state and site occupancy of the magnetic Mn ions in the ZnO lattice. Moreover, UV–vis absorption spectra have been utilized to calculate the optical band gap of the undoped ZnO and ZnO:Mn nanoparticles before and after different γ-irradiation doses. The band gap of ZnO:Mn (2%) is 2.62eV which is noticeably smaller than the 3.26eV of undoped ZnO. The thermal decomposition properties of the prepared nanoparticle samples were also studied using simultaneous Thermogravimetric analysis in temperature range from 30 to 500°C.

Structure and morphologies of ZnO nanoparticles synthesized by pulsed laser ablation in liquid: Effects of temperature and energy fluence

Zinc oxide nanoparticles were prepared by pulsed laser ablation of a zinc metal target at different water temperatures (room temperature, 50, 70 and 90 °C). Ablation was carried out using 532 nm output from a pulsed (10 ns, 10 Hz) Nd:YAG laser at three different laser fluence. Analysis of the morphology, crystalline phase, elemental composition, optical and luminescent properties were done using Transmission Electron Microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS), UV–visible absorption spectroscopy and photoluminescence spectroscopy. TEM analysis showed that a change in temperature resulted in ZnO and Zn(OH)2 nanoparticles with different sizes and morphologies. XPS results confirmed the compositions and chemical states of these nanoparticles. These zinc nanomaterials showed emission in the ultraviolet (UV) and blue regions. The results of this work demonstrated that by varying the liquid medium temperature, the structure, composition, morphology and optical properties of the nanomaterials could be modified during pulsed laser ablation in liquid.

Direct and indirect sonication affect differently the microstructure and the morphology of ZnO nanoparticles: Optical behavior and its antibacterial activity

In the present study, the sono-synthesis of ZnO nanoparticles (NPs) was performed by simple, low-cost, and the environmentally friendly method. The synthesis of zinc oxide as an antibacterial agent was performed by an ultrasonic bath (low intensity) for the indirect sonication and a horn system (high intensity) for the direct sonication. The samples synthesized by these two kinds of sonication were compared with each other. Crystallographic structures and the morphologies of the resultant powders were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns showed that both ZnO samples were crystallized in their pure phase. The TEM images confirmed that the morphologies of the products were completely different from each other. Based on the obtained analysis, the probable growth mechanisms were proposed for crystallization of both samples. The antibacterial activity of the synthesized species was evaluated by the colony count method against Escherichia coli O157:H7. Moreover, the optical behavior of the samples was studied by UV–vis spectroscopy and the variation of the ZnO band gap was compared.

DNA-Mediated Fast Synthesis of Shape-Selective ZnO Nanostructures and Their Potential Applications in Catalysis and Dye-Sensitized Solar Cells

Shape-selective ZnO nanoparticles (NPs) with various morphologies have been synthesized within 2 min of microwave heating by the reaction of Zn(NO3)2·2H2O with NaOH in the presence of DNA. The size and shape of the materials can be tuned by controlling the molar ratio of Zn(II) salt to DNA and by altering the other reaction parameters. The role of DNA and other reaction parameters for the formation and growth mechanisms of different morphologies has been elaborated. The potentiality of the DNA–ZnO NPs has been tested in the catalysis reaction for the decomposition of toxic KMnO4, and the effect of different morphologies on the catalysis reaction has been examined. Moreover, the suitability of the materials is also tested for dye-sensitized solar cell (DSSC) applications, and it was observed that all the morphologies of ZnO NPs can be used as a potential anode material in DSSC applications.

Study of defect generated visible photoluminescence in zinc oxide nano-particles prepared using PVA templates

Intrinsic defect generated photoluminescence (PL) in zinc oxide nanoparticles (NPs) obtained by a PVA template based wet-chemical process has been studied. A good controllability was achieved on the surface defects, structure and the morphology of ZnO NPs through the variation of solvents used in synthesis. The PL emission strongly depended on the defect structure and morphology. SEM, XRD, annealing and PL excitation studies were used to analyze the types of defects involved in the visible emission as well as the defect concentration. The mechanism for the blue, green and yellow emissions was proposed. The spectral content of the visible emission was controlled through generation/removal of defects through the shape transformation or annealing by focusing on defect origins and broad controls.

Processing temperature driven morphological evolution of ZnO nanostructures prepared by electro-exploding wire technique

This article presents an effective approach for the synthesis of ZnO nanoparticles with desired morphology via an environmentally benevolent electro-exploding wire (EEW) technique. In this process, ZnO nanoparticles evolve through the plasma generated from the parent Zn metal. Compared to other typical chemical methods, electro-exploding wire technique is a simple and economical technique that normally operates in water or organic liquids under ambient conditions. The effect of different processing temperatures in the range (5–80 °C), on the morphology of ZnO nanoparticles is clearly demonstrated. At 5 °C, nanoparticles with spherical morphology are observed. However, elliptical morphology is observed at room temperature and multipod nanorods at 50 °C and 80 °C. The evolution of ZnO phase is investigated with the help of time dependent UV-vis absorption and photoluminescence (PL) studies. The mechanism of formation and different morphologies of ZnO nanoparticles formed are also proposed.

Structural and Morphological Properties of Nanostructured ZnO Particles Grown by Ultrasonic Spray Pyrolysis Method with Horizontal Furnace

ZnO nanoparticles were synthesized in a horizontal furnace at 500°C using different zinc nitrate hexahydrate concentrations (0.01 and 0.1 M) as reactive solution by ultrasonic spray pyrolysis method. The physical-chemical properties of synthesized ZnO nanoparticles have been characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and high resolution transmission electron microscopy (HRTEM). With the TGA is has optimized the temperature at which the initial reactive (Zn(NO3)2·6H2O), is decomposed completely to give way to its corresponding oxide, ZnO. SEM revealed secondary particles with a quasispherical shape that do not change significantly with the increasing of precursor solution concentration as well as some content of the broken spheres. Increasing the precursor solution concentration leads to the increase in the average size of ZnO secondary particles from248±73to470±160 nm; XRD reveals the similar tendency for the crystallite size which changes from23±4to45±4 nm. HRTEM implies that the secondary particles are with hierarchical structure composed of primary nanosized subunits. These results showed that the precursor concentration plays an important role in the evolution on the size, stoichiometry, and morphology of ZnO nanoparticles.

Effect of Tin Loading on Physical Properties and Phase Transformation of as-synthesized Zn-Sn-O Compound Powder Synthesized by Co-precipitation Method

Zinc-Tin oxide compounds (Zn-Sn-O) were successfully prepared via a facile co-precipitation process using zinc dichloride dihydrate as the zinc source and tin tetrachloride pentahydrate as an additive source. The as-prepared product of Zn-Sn-O powders with various Sn additive contents (0-60%wt) were obtained without calcinations process. The effect of Sn additive on structural and microstructure properties of the samples were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM). The results indicate that the crystallinity and morphologies of ZnO nanoparticles are significantly influenced by Sn additive. The phase formations of Zn-Sn-O including ZnO, ZnSn(OH)6 were observed depending on the Sn-additive composition.

Change in the morphology of ZnO nanoparticles upon changing the reactant concentration

ZnO plays an important role in many techno- logical aspects of semiconductors. Because of its interesting properties, it has attracted a great deal of attention for a wide range of applications. In this work, the direct precipitation method was employed for the synthesis of ZnO nanoparticles to study the role of different concentration ratios of reactants on the crystal structure, size, and morphology of the prepared ZnO nanoparticles. The reactant raw materials used in this experiment were zinc acetate dihydrate as a zinc source and NaOH. ZnO nanoparticles were synthesized by calcination of the ZnO precursor precipitates at 250 Cf or 3 h. These calcinated ZnO nanoparticles and their properties were characterized using X-ray diffraction, a scanning electron microscope equipped with an energy dispersive X-ray spectrometer, and transmission electron microscopy. We present the experiment conditions, including result on the different reactant concentration ratios, which affect the control of the size and morphology of the ZnO nanoparticles. The mean size of the ZnO nanoparticles was 18 nm.

Effect of Ammonia Water on the Morphology of Monoethanolamine-Assisted Sonochemicaly Synthesized ZnO Nanostructures

In the present work, ZnO nanostructures were synthesized by monoethanolamine (MEA)-assisted ultrasonic method at low temperature. Structural analysis was carried out by X-ray diffraction (XRD) confirmed the formation of hexagonal wurtzite structure of ZnO. The effect of ammonia water on the molecular structure of MEA, and its effect on the morphology of ZnO nanostructures were monitored by electron microscopy. Scanning electron microscopy (SEM) results suggest that ZnO nanoparticles with 100 nm in diameter were produced in case of MEA-assisted ultrasonic method. However, as ammonia water was added into the reaction system the morphology of ZnO nanoparticles changed into nanorods, flower-like nanostructures and finally microrods. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) studies showed that as prepared ZnO nanostructures were single crystalline in nature and grew in different directions resulted in the formation of various structures. The growth mechanism of as prepared ZnO nanostructures was discussed in detail. It was proposed that the addition of ammonia water into the reaction system resulted into the formation of ethylene diamine (EDA) which directed the growth of ZnO. The optical property was studied by photoluminescence (PL) spectroscopy showed only UV emission and no defects mediated visible emission.

Influence of Al nitrate and Al chloride doping sources on structural and optical properties of sol–gel derived Al:ZnO nanoparticles

Al-doped ZnO nanoparticles have been synthesised via sol–gel method. Aluminum nitrate and aluminum chloride, as two widespread doping sources, have been compared in various Al/Zn molar ratios of 0.1, 0.5, 1, 2 and 5. After sol preparation, all samples with different Al content have been aged and then dried at 120°C. The resultant grinned powders calcined at different temperatures of 400, 500, and 600°C. X-ray diffraction (XRD) method has been used to investigate crystallisation behaviour and structural properties of samples. Less crystallinity in chloride source samples is detected compared to the nitrate source; however, identical distortion of hexagonal wurtzite unit cell in both sources was evident in XRD results. Field emission scanning electron microscopy demonstrates semisphere morphology of ZnO nanoparticles with particle size less than 60 nm. Fourier transform infrared spectroscopy was conducted to find possible chemical reactions and complexes during the sol–gel process in different Al source samples. UV-vis spectroscopy was carried out to find optical properties of the Al:ZnO samples. The results represent different optical properties in Al chloride and Al nitrate sources.

Label-free and enhanced DNA sensing platform for PML/RARA fusion gene detection based on nano-ZnO functionalized carbon ionic liquid electrode

A novel electrochemical impedance DNA biosensor for acute promyelocytic leukemia was developed by immobilizing a PML/RARA related 18-mer oligonucleotides ssDNA sequence on carbon ionic liquid electrode modified with nanosized ZnO. The morphology of ZnO nanoparticles was characterized by using scanning electron microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy were performed for the study of decoration of ZnO, immobilization of ssDNA and the hybridization event at the electrode surface. Remarkable change has been observed in the impedance spectra before and after hybridization of probe ssDNA with the target DNA under optimal conditions. As a result, the effective probe immobilization platform, coupled with the ultrasensitive label-free impedance measurement, gave rise to a detection limit of 2.5×10−13mol/L.

Preparation and characterization of poly(2‐hydroxyethylme thacrylate)‐b‐P(N‐phenylmaleimide)‐ZnO and poly(2‐hydroxy ethylmethacrylate)‐b‐P(styrene)‐ ZnO micro/nanostructures: micro/nanocomposite particles with core‐shell morphology

AbstractThe present work reports the incorporation of the ZnO doped diblock copolymer matrix and its conversion into a self‐assembled structure. The diblock P(HEMA)80‐b‐P(N‐PhMI)20 and P(HEMA)90‐b‐P(St)10 copolymers consist of a majority (HEMA) and minority (N‐PhMI or St) block. The copolymers were synthesized with a block repeat unit ratio by atom‐transfer radical polymerization (ATRP) using a poly(2‐hydroxyethylmethacrylate)‐Cl/CuBr/bipyridine initiating system. The P(HEMA)‐Cl was prepared by reverse ATRP1. The average theoretical number molecular weight (Mn,th) was calculated from the feed capacity. The composite of the inorganic nanoparticles was achieved at room temperature in the liquid phase, using ZnCl2 precursor dopant and wet chemical processing to convert to ZnO nanoparticle films. Thermal characterization was performed using differential scanning calorimetry (DSC) and thermogravimetry (TG). The proton/area relationship confirmed the block copolymer compositions calculated by elemental analysis, consisting of a majority and minority blocks. Morphology properties of the polymer samples were investigated by scanning electron microscopy (SEM). The microphotographs of the film's surfaces show that the film's upper surfaces were generally smooth with ordered structure morphology. FT‐IR spectroscopy confirmed the association of the ZnCl2 precursor with the majority block and the formation of ZnO, the white SEM showed the morphology of ZnO nanoparticles' films when the surface relief changes principally due to surface loss rather than its orientation. Copyright © 2009 John Wiley & Sons, Ltd.

Microwave assisted fast synthesis of various ZnO morphologies for selective detection of CO, CH 4 and ethanol

ZnO nanocrystals with various morphologies were synthesized via a fast and facile microwave assisted method using zinc acetate as starting material, guanidinium and acetyl acetone as structure directing agents, and water as solvent. Reaction conditions, templates and pH of the reaction medium were adjusted in order to achieve nanorod, nanoparticle, and flower-like morphologies. As synthesized ZnO samples were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption analysis (BET). Response and selectivity of the samples to CO, CH 4 and ethanol were measured in a flow system. It is shown that different morphologies of ZnO nanoparticles exhibit different responses and selectivities. Flower-like morphology is highly selective to CO, while nanorods and nanoparticles are selective to methane and ethanol, respectively. Moreover, in a wide range of temperatures, response of ZnO nanorods and nanoparticles towards CO is temperature independent.

Tuning the aspect ratio of hydrothermally grown ZnO by choice of precursor

Variable aspect ratio (length/diameter), one dimensional ZnO nanostructures are synthesized by reacting Zn 2+ precursor derived from Zn·Ac 2, Zn·Cl 2 and Zn·(NO 3) 2 under hydrothermal treatment. The growth mechanism illustrating the formation of self-assembling from individual ZnO nanoparticles to rod-like form is explained briefly. XRD reveals that the ZnO obtained from various zinc salts are pure, wurtzite structure, with crystalline hexagonal phase. The qualitative analysis of ZnO formation and morphology of ZnO nanoparticles are estimated from FESEM and TEM micrographs. Strong UV absorption corresponding to the recombination of electron–hole pair is observed and the blue shift absorption obeys the size confinement effect. The extent of absorption relatively varies when the morphology is changed from nano-bundles to individual rod-like ZnO. When electrons are excited at wavelength of 240 nm, a strong near band edge (NBE) emission and surface defects emission are observed in the PL spectra. The broader emission situated in the blue-green region of the visible spectrum, originating from surface oxygen defects, is not observed in ZnO derived from Zn·Ac 2.

Highly concentrated zinc oxide nanocrystals sol with strong blueemission

Abstract Highly concentrated ZnO sol was synthesized by an improved sol–gel method. Water was used as a modifier to control the sol–gel reaction and provide a way to increase the sol concentration. Concentration of ZnO in the prepared sol is higher than from other methods. Optical absorption and photoluminescence were used to investigate optical properties of the prepared sol. FTIR test was performed to study the influence of water on the compounds of as-prepared sol. The size and morphology of ZnO nanoparticles have been studied by HRTEM. The prepared colloidal ZnO nanocrystals have narrow size distribution (5–8 nm) and showed strong blue emission. The prepared sol has enough potential for optoelectronic applications.

A study of the tribological behavior of nano-ZnO-filled polyurethane composite coatings

The two different morphologies of ZnO nanoparticles and ZnO whiskers were used as the friction modifiers to improve the tribological behavior of the polyurethane (PU) composite coating. The tribological behavior of the PU coatings filled with different morphologies nanometer ZnO was investigated using a ring-on-block wear tests under dry friction condition, and the worn surfaces and the transfer films formed on the surface of counterpart ring were, respectively, studied by scan electric microscope (SEM) and optical microscope (OM). It was found that the addition of the low inclusion of ZnO nanoparticles and ZnO whiskers can improve the reducing-friction and anti-wear abilities of the PU coatings and ZnO whiskers, as the filler was superior to ZnO nanoparticles in terms of the ability to decrease friction coefficient and wear rate of the PU coating. The investigations of the worn surfaces showed that the fillers of ZnO nanoparticles and ZnO whiskers were able to enhance the adhesion of the transfer films of the PU coating to the surface of counterpart ring, so they significantly reduced the wear rate of the PU coating.

Facile synthesis of ZnO nanoparticles based on bacterial cellulose

ZnO nanoparticles with a pure wurtzite structure have been successfully synthesized through decomposing bacterial cellulose infiltrated with zinc acetate aqueous solution at high temperature. The effects of the concentration of zinc acetate aqueous solution, the calcination temperature, and the templates on the average particle size and morphology of the ZnO nanoparticles were investigated. The prepared ZnO nanoparticles were characterized by FESEM, XRD, FTIR and TG–DTA. The results suggest that bacterial cellulose plays an important role in preventing the ZnO nanoparticles from aggregating under optimized conditions. The calcination temperature has great effects on the morphologies of ZnO nanoparticles. When calcinating at 600 °C and using BC as the template with 1 wt.% zinc acetate aqueous solution, well-dispersed and regular ZnO nanoparticles with a narrow size distribution of 20–50 nm and high photocatalytic activity were obtained.

ZnO nanofluids: Green synthesis, characterization, and antibacterial activity

Zinc oxide nanoparticles have been synthesized by microwave decomposition of zinc acetate precursor using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [bmim][NTf 2] as a green solvent. The structure and morphology of ZnO nanoparticles have been characterized using X-ray diffraction and transmission electron microscopy. The ZnO nanofluids have been prepared by dispersing ZnO nanoparticles in glycerol as a base fluid in the presence of ammonium citrate as a dispersant. The antibacterial activity of suspensions of ZnO nanofluids against ( E. coli) has been evaluated by estimating the reduction ratio of the bacteria treated with ZnO. Survival ratio of bacteria decreases with increasing the concentrations of ZnO nanofluids and time. The results show that an increase in the concentrations of ZnO nanofluids produces strong antibacterial activity toward E. coli.