Growth Of ZnO Nanoparticles Research Articles

Photocorrosion Suppression of ZnO Nanoparticles via Hybridization with Graphite-like Carbon and Enhanced Photocatalytic Activity

A method to suppress the photocorrosion of ZnO nanoparticles was developed by surface hybridization of ZnO with graphite-like carbon layers. The presence of carbon on the surface of the ZnO could significantly suppress the coalescence and crystal growth of ZnO nanoparticles during high-temperature treatment. The nanosized structure of ZnO was well preserved even after high-temperature calcination. The photocatalytic activity of ZnO was enhanced by hybridization with carbon layers attributed to the improved adsorption ability and crystallinity. The as-prepared samples exhibited high activity even after 720 h of photocatalysis reaction, while the pure ZnO nanoparticle was almost deactivated in 100 h due to serious photocorrosion. The as-prepared samples also showed much better activity under extreme pH conditions than that of pure ZnO. The mechanism of photocorrosion suppression and higher stability was then systematically investigated based on the crystal structure and the photocatalysis degradation process.

Zinc oxide nanoparticle growth from homogenous solution: Influence of Zn:OH, water concentration, and surfactant additives

Zinc oxide particle growth from homogeneous solution was monitored using in situ UV–vis spectroscopy. Final particle size and overall growth rate increased with increasing zinc to hydroxide concentration ratio and were both sensitive to the surfactant added. Particle growth was fit using two models: (1) the classic coarsening model and (2) the simultaneous coarsening and oriented aggregation model. Results demonstrate that using adamantane carboxylic acid as a surfactant additive inhibits ZnO nanoparticle growth both by coarsening and oriented aggregation as compared to using other monocarboxylates (e.g., acetate and tribromoacetate). In addition, ZnO nanoparticle growth was independent of water concentration within the range of 40–100 mM for the conditions studied here (1 mM zinc perchlorate, 1.6 mM hydroxide, and 0.38 mM adamantane carboxylic acid). High-resolution transmission electron micrographs confirm inhibited growth by oriented aggregation for ZnO grown with adamantane carboxylic acid. Results are compared to previous work and generally show that ZnO growth by coarsening and oriented aggregation can be selectively inhibited or promoted by judicious selection of the surfactant additive.

A solid-state dye-sensitized solar cell based on a novel ionic liquid gel and ZnOnanoparticles on a flexible polymer substrate

This paper describes a new strategy to make a full solid-state, flexible, dye-sensitized solarcell (DSSC) based on novel ionic liquid gel, organic dye, ZnO nanoparticles and carbonnanotube (CNT) thin film stamped onto a polyethylene terephthalate (PET) substrate.The CNTs serve both as the charge collector and as scaffolds for the growth of ZnOnanoparticles, where the black dye molecules are anchored. It opens up the possibility ofdeveloping a continuous roll to roll processing for THE mass production of DSSCs.

Growth of ZnO nanoparticles and nanorods with ultrafast pulsed laser deposition

In this work, we study the application of ultrafast pulsed laser deposition (PLD) in ZnO nanomaterial synthesis, including nanoparticles and nanorods. PLD using long pulse (nanosecond) lasers has been widely used as a method for growing prototype materials. The recently-emerged ultrafast PLD is expected to be able to overcome the problem of large liquid droplet formation. Using near infrared and femtosecond laser pulses in ablation, we first characterize the ablation plume using a Langmuir probe and plasma optical emission spectroscopy. We then examine the structural properties of the nanoparticles generated during low-fluence ablation. Finally, we demonstrate that using nanoparticle aggregates as templates, assisted by plume-excited nitrogen radicals at a high fluence, high quality ZnO nanorods can be grown free of metal catalysts.

Nucleation and growth of ZnO nanocrystals in polymer films

A facile layer-by-layer method was used to prepare ZnO nanoparticles embedded in multilayers polymer films. The polymer matrix was formed by layer-by-layer self-assembly technique. By repetitive adsorption of zinc nitrate and subsequent precipitation with ammonium hydroxide, polyelectrolyte multilayer films containing ZnO nanoparticles were fabricated. UV–vis spectra indicate the regular growth of ZnO nanoparticles. Transmission electron microscopy study shows that morphology of the nanoparticles is controlled by the precipitation cycles number. The formation process of the nanoparticles in the multilayers was also discussed.

A different chemical route to synthesize ZnO nanoparticles

A new reaction was developed to synthesize ZnO nanoparticles with nearly uniform, spherical morphology ranging from 25 to 50 nm via directly oxidizing zinc powders with iodine in ethanol. Iodine plays key roles in the nucleation of ZnO nanoparticles and it is favorable for the growth of ZnO nanoparticles gradually and avoids the agglomeration to some extent. Moreover, this process is well repeatable and easy controlled. The morphology evolution of the ZnO nanoparticles at different reaction time was monitored through transmission electron microscope (TEM). The room temperature photoluminescence (PL) spectrum displays strong ultraviolet emission peaks and relative weak near band-edge free excitonic emission peak.

Form Emerges from Formless Entities: Temperature‐Induced Self‐Assembly and Growth of ZnO Nanoparticles into Zeptoliter Bowls and Troughs

Form Emerges from Formless Entities: Temperature‐Induced Self‐Assembly and Growth of ZnO Nanoparticles into Zeptoliter Bowls and Troughs

Form Emerges from Formless Entities: Temperature‐Induced Self‐Assembly and Growth of ZnO Nanoparticles into Zeptoliter Bowls and Troughs

Shaping up: Unusual bowl-, trough-, and ring-shaped structures result from the temperature-induced self-assembly of nanoparticles (see picture for bowl). The obtained ZnO bowls and rings also serve as a template to make metal or metal oxide replicas. The tiny bowls are envisaged not only to hold fluids of ultralow volume, but also to grow nanoparticles, immobilize biomolecules, and screen sub-micrometer-sized particles. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z701771_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

ZnO nanoparticle growth on single-walled carbon nanotubes by atomic layer deposition and a consequent lifetime elongation of nanotube field emission

ZnO nanoparticles were grown on single-walled carbon nanotubes (SWNTs) by atomic layer deposition using diethylzinc (DEZ) and water. The athors discuss that, because of chemical inertness of nanotubes to DEZ and water molecules, such nanoparticles are not likely to grow on the wall of clean and perfect nanotubes. Rather, the growth of ZnO nanoparticles should be attributed to imperfection of nanotubes, such as defects and carbonaceous impurities. Lifetime of field emission from SWNTs with the ZnO nanoparticles is 2.5 times longer than that from the as-grown nanotubes. It is thought that the protection of the defects or impurities by ZnO nanoparticles mainly contributed to the improvement of the field emission lifetime from SWNTs.

ZnO/mesoporous silica nanocomposites prepared by the reverse micelle and the colloidal methods: Photoluminescent properties and quantum size effect

Quantum size effect was demonstrated in ZnO/mesoporous silica nanocomposites prepared by two different routes: the reverse micelle strategy and the colloidal method owing to a fine tuning of particles grown by the control of mesopore size. N 2 adsorption–desorption measurements, Atomic Absorption and Photoluminescent spectroscopy have evidenced the efficient loading and growth of ZnO nanoparticles in the channels of the mesoporous silica matrix. The present work illustrated that both methods are quite efficient in the preparation of short wavelength (blue) laser nanocomposite.

In situ UV–vis and EXAFS studies of ZnO quantum-sized nanocrystals and Zn-HDS formations from sol–gel route

We have pointed out that, zinc-based particles obtained from zinc acetate sol–gel route is a mixture of quantum-sized ZnO nanoparticles, zinc acetate, and zinc hydroxide double salt (Zn-HDS). Aiming the knowledge of the mechanisms involved in the formation of ZnO and Zn-HDS phases, the thermohydrolysis of ethanolic zinc acetate solutions induced by lithium hydroxide ([LiOH]/[Zn 2+] = 0.1) or water ([H 2O]/[Zn 2+] = 0.05) addition was investigated at different isothermal temperatures (40, 50, 60 and 70 °C) by in situ measurements of turbidity, UV–vis absorption spectra and extended X-ray absorption fine structures (EXAFS). Only the growth of ZnO nanoparticles was observed in sol prepared with LiOH, while a two-step process was observed in that prepared with water addition, leading the fast growth of Zn-HDS and the formation of ZnO nanoparticles at advanced stage. A mechanism of dissolution/reprecipitation governed by the water/ethanol proportion is proposed to account for relative amount of ZnO.

Solvothermal Synthesis of ZnO with Various Aspect Ratios Using Organic Solvents

Nanocrystalline ZnO powders were synthesized by a solvothermal method using various organic solvents as the reaction medium. Products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The aspect ratio of ZnO primary particles depended upon the solvent employed, such that the aspect ratio increased when the solvent with a low dielectric constant was employed. For the use of n-alkanes and aromatic compounds as solvent, ZnO nanorods were obtained. The polar characteristic of the solvent was proposed to be the main factor that affects both nucleation and growth of ZnO nanoparticles and, consequently, determines the aspect ratio of the products.

Nucleation and Growth of ZnO Nanoparticles in Alcohols. Force-Hydrolysis vs Self-Hydrolysis.

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Size dependent absorption spectrum of ZnO nanocrystals

To investigate the dependences of the absorption spectrum and electronic structure properties on the ZnO nano-particle size, ZnO nanocrystals were synthesized by a sol-gel method. The absorption onset peak exhibits a systematic blue-shift with decreasing particle size due to the quantum confinement effect, as well as, with decreasing <TEX>$Zn^{2+}$</TEX> concentration. The increase of particle size is mainly controlled by coarsening and aggregation step during the nucleation and growth of ZnO nano-particles. The onset absorption spectrum of ZnO colloids changes from 310 to 355 nm as <TEX>$Zn^{2+}$</TEX> concentration increases from 0.01 to 0.1 mole. The average particle size as a function of aging- time can be determined from the absorption spectra. The freshly prepared nanocrystal size was about 2.8nm.

Quenching of Growth of Zinc Oxide Nanoparticles by Adsorption of Organic Stabilizers

We examined quenching of growth of ZnO nanoparticles with the injection of various organic surfactants. Aliphatic isocyanides as well as organothiols were found to adsorb on ZnO nanoparticle surfaces. For a carboxylate-terminated thiol, a retardation of growth appeared to be effective presumably due to the adsorption of the carboxylate COO- group on the ZnO surface. Photoluminescence spectra and transmission electron microscopy images were obtained for thiolcapped ZnO nanoparticles. The thiol-capped ZnO nanoparticles was found to fluoresce at the wavelength shorter by ~6 nm than those in the absence of any organic surfactants.

Influence of solvent on the growth of ZnO nanoparticles

We have synthesized ZnO nanoparticles by precipitation from zinc acetate in a series of n-alkanols from ethanol to 1-hexanol as a function of temperature. In this system, nucleation and growth are relatively fast and, at longer times, the average particle size continues to increase due to diffusion-limited coarsening. During coarsening, the particle volume increases linearly with time, in agreement with the Lifshitz–Slyozov–Wagner (LSW) model. The coarsening rate increases with increasing temperature for all solvents and increases with alkanol chain length. We show that the rate constant for coarsening is determined by the solvent viscosity, surface energy, and the bulk solubility of ZnO in the solvent.

Synthesis and characterization of ZnO nanostructures templated using diblock copolymers

AbstractThe development of self‐assembled ZnO nanoparticles within a diblock copolymer matrix using wet chemical processing specific to ZnO is reported. Diblock copolymers consisting of polynorbornene and poly(norbornene–dicarboxcylic acid) (NOR/NORCOOH) were synthesized with a block repeat unit ratio of 400 for the first block and 50 for the second block, to obtain spherical microphase separation. The block copolymer self‐assembly was used to template the growth of ZnO nanoparticles by introducing a ZnCl2 precursor into the second polymer (NORCOOH) block at room temperature and processing the copolymer by wet chemical methods to substitute the chlorine atoms with oxygen. X‐ray photoemission spectroscopy (XPS) verified the conversion of ZnCl2 to ZnO by monitoring the disappearance of the Cl 1s peak and the shift in the binding energy of the Zn 2p3 peak in the high‐resolution spectra. The substitution of Cl by O was found to be a highly preferential process, whereby only one approach using a weak base (NH4OH) succeeded in effectively replacing Cl with O to result in spherical ZnO nanoparticles having a size ranging from 7 to 15 nm, as determined by transmission electron microscopy. The development of such block copolymer‐templated ZnO nanoparticles% is important in enabling the functionalization of large‐area nanodevice technologies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1058–1061, 2003

Quenching of Growth of ZnO Nanoparticles by Adsorption of Octanethiol

To exploit the size dependent properties of nanoparticles, it is essential to control the particle size. We show that injection of octanethiol into suspensions of ZnO particles can be used to quench particle growth. X-ray photoelectron spectroscopy studies of the adsorption of octanethiol on ZnO single crystals indicate relatively weak adsorption of thiolate and sulfonate species dependent on the crystal orientation. These results suggest that adsorption of thiolate and sulfonate groups on ZnO particles in suspension prevent dissolution of the solid phase. Furthermore, the octanethiol is adsorbed sufficiently strongly to quench growth but can be easily removed for subsequent surface functionalization.

Influence of Organic Capping Ligands on the Growth Kinetics of ZnO Nanoparticles

The growth of ZnO nanoparticles from zinc acetate in propanol proceeds by coarsening. The driving force for this process is the increase in equilibrium solubility with decreasing particle size, described by the Gibbs−Thompson equation. We show that the growth rate, and hence particle size, can be controlled by injection of capping ligands that adsorb onto the particle surface. Both thiols and phosphonic acids are shown to slow the growth rate of ZnO nanoparticles, indicating that they adsorb onto the particle surface and provide a barrier to further dissolution.

Synthesis and Growth of ZnO Nanoparticles

ZnO nanoparticles in the size range from 2 to 7 nm were prepared by addition of LiOH to an ethanolic zinc acetate solution. This method [Spanhel, L.; Anderson, M. A. J. Am. Chem. Soc. 1991, 113, 2826] was modified and extended at several points. The synthesis of very small ZnO nuclei was simplified. It was found that aging of particles was governed by temperature, the water content, and the presence of reaction products. Water and acetate induced considerably accelerated particle growth. Growth could almost be stopped by removal of these species (“washing”). Washing consisted of repeated precipitation of ZnO by addition of alkanes such as heptane, removal of the supernatant, and redispersion in ethanol. The aging characteristics are interpreted in terms of the concentration of dissolved ZnII species and reactions well-known in sol−gel chemistry. These findings present a better-defined and more versatile procedure for production of clean ZnO sols of readily adjustable particle size. Such sols are of particular interest for studies of electrical and optical properties of ZnO nanoparticle films. For example, films exhibiting >99% transparency in the visible region could only be obtained by deposition from a washed sol.