One-dimensional Zinc Oxide Research Articles

Facile synthetic route for producing one-dimensional zinc oxide nanoflowers and characterization of their optical properties

The morphologies and unique properties of zinc oxide nanoflowers make the nanoflowers promising candidates for use in wide range of future technological device applications. This paper describes the use of a versatile single-step synthetic route for producing ZnO nanoflowers under hydrothermal conditions at various reaction times. High-quality ZnO crystal was obtained after only 4 h by using this synthetic route. The morphology evolution and the length of rods that compose the flowers were monitored using SEM and ImageJ software. From the SEM images, it was possible to identify the formation of pure ZnO nanoflowers after 15 min under hydrothermal conditions. The length of the nanoflowers and the presence of defects in their morphology directly affected their optical properties, as examined using UV–visible and photoluminescence spectrophotometry. For samples kept at 5 and 10 min under similar conditions the time was not enough to form nanoflowers of pure ZnO materials. Actually, the samples are composed by two phases with zinc hydroxide being majority (>95%) and morphology like-rods.

Zinc oxide flower-like synthesized under hydrothermal conditions

One-dimensional zinc oxide with flower like configuration was synthesized onto a conductor glass substrate (fluorine-doped tin oxide — FTO) at 90°C during 4 and 16h. The zinc oxide formation occurs without any use of pre-seed layer or reactants to increase ionic strength of medium, neither addition of surfactant to act as capping agents for controlling morphology or special treatment on the commercial FTO substrate, making this an efficient and inexpensive procedure. X-ray diffraction analysis evidences a structure composed by single crystal in the wurtzite phase. The flower-like configuration observed by field emission scanning electronic microscopy images was promoted by the interaction between the reactant used to prepare the initial solution with pH adjusted at 10.5. This pH value is found, by titration study (triplicate) and in agreement with many reports in the literature, to promote the powder formation of zinc oxide with flower-like configuration. Tubular ZnO flower-like formation on the FTO was attributed to etching caused by ammonia in high concentration during the hydrothermal synthesis. In addition, our experimental results combined with theoretical ab initio calculation lead us to propose that the formation of tubular flower-like zinc oxide films proceeds in three steps, when prepared by hydrothermal process at different times (at T=90°C).

One-Dimensional (1D) ZnO Nanowires Dye Sensitized Solar Cell

High ordered one-dimensional (1D) Zinc oxide (ZnO) nanowires were grown on FTO substrate by using the hydrothermal method. Nanowires structures were used as the wide band-gap semiconducting photo-electrode in dye sensitized solar cell (DSSCs). Solar cell made from ZnO nanowire at 50 nm radius and several tens micron lengths showed high solar conversion efficiency (eta) of 2.1% and incident photon current efficiency (IPCE) 35% using nanowire/N719 dye/I-/I3- electrolyte. We also compared Ru N719 dye and N3 dye on ZnO nanowire against each other in respect to solar conversion efficiency and IPCE measurements. In the case of the N3 dye on ZnO nanowire conversion efficiency (eta) of 1.32% and IPCE 23% were obtained under an illumination of 100 mW/cm2. It was found that the performance of the Ru N719 dyes was better than about 50% that of the N3 dye in ZnO nanowire dye-sensitized solar cells.

Scalable synthesis and device integration of self-registered one-dimensional zinc oxide nanostructures and related materials

On integrating one-dimensional (1D) nanocrystals (nanowires) to useful devices, in this review article, we provide a background on vapor-based growth processes and how they impact device integration strategies. Successful integration of nanowires to devices and their scalability simply rely on where and how nanowires are formed, how they are interfaced to other device components and how they function. In this direction, we will provide a discussion on developed growth strategies for lateral and standing growth of semiconductor nanostructures and assess their success in addressing current challenges of nanotechnology such as mass integration of nanowires, and the necessary accuracy in their positioning and alignment. In this regard, we highlight some of our recent work on formation of two-dimensional (2D)- and three-dimensional (3D)- nanowire and nanowall arrays and provide an overview of their structural and electro-optical properties. This will be followed by discussing potential applications of such hierarchical assemblies in light generation, photocatalysis and conversion of motion to electricity.

Chemically synthesized one-dimensional zinc oxide nanorods for ethanol sensing

One-dimensional (1D), single-phase (002) crystalline zinc oxide (ZnO) nanorod (NR) based conductometric sensors have been developed and investigated toward ethanol (C2H5OH) vapor. The ZnO NRs were chemically deposited onto conductometric transducer of alumina substrates employing a simple hydrothermal method. To facilitate the nucleation of ZnO NRs for oriented growth from the substrate, a seed layer of ZnO nanoparticles was pre-deposited employing filtered cathodic vacuum arc (FCVA) deposition technique onto the substrate containing pre-patterned interdigital electrodes (IDTs). Micro-characterization studies revealed that the NRs have a single crystal 1D structure with an average diameter of 30–50nm. The developed sensors were exposed toward ethanol of different concentrations at temperature up to 330°C. An optimum sensor operational temperature was found between 280 and 310°C. At this temperature range, high sensitivity, fast response and fast recovery in conjunction with a stable baseline occur. The long-term stability test of the developed sensors confirmed that they are highly stable with only less than 3% variation of the dynamic performances (baseline resistance, sensitivity, response and recovery time).

Effect of the Thickness of Quasi One-Dimensional Zinc Oxide Nanorods Synthesized via Multiple Growth Process under Ammonia Assisted Hydrolysis Technique on the Performance of Dye-Sensitized Solar Cell

Effect of the Thickness of Quasi One-Dimensional Zinc Oxide Nanorods Synthesized via Multiple Growth Process under Ammonia Assisted Hydrolysis Technique on the Performance of Dye-Sensitized Solar Cell

Effects of graphite additive on dielectric properties and microwave absorption properties of zinc-containing foam glass

This paper reports effects of graphite additive on dielectric properties and microwave absorption performances of zinc-containing foam glasses. Changes of pore structure of porous glass are analyzed. One-dimensional zinc oxide crystal whiskers on walls of foam glass are observed. With the graphite additive increases, both real (ε′) and imaginary (ε″) parts of complex permittivity increase from ~3.25 and ~0.2 to ~7.5 and ~2.8, respectively. Microwave reflection loss of porous glass was calculated based on the permittivity in the range of 8.2–12.4GHz(X-band). Reflection loss of foam glass decreases as graphite additive and the sample with 2.0wt% graphite additive achieve reflection loss less than −10dB in whole X-band with thickness ranging from 2.3 to 3.5mm. Linear relation between reduction of reflectivity and increase of graphite content is achieved. The results show that changing foaming agent additive is an efficient way to design dielectric and microwave absorption properties of foam glass. Foam glass with 1.0wt% graphite additive may find application in photocatalytic degradation of many environmental pollutants due to its considerable zinc oxide whiskers.

Progress on one-dimensional zinc oxide nanomaterials based photonic devices

Abstract One-dimensional nanostructures hold the most attractive and excellent physiochemical characteristics which exhibit the paramount influence on the fundamental and technological nanoelectronic as well as nanophotonic applications. In this review article, we present a detailed introduction to the diverse synthetic procedures which can be utilized for the fabrication of single-, planar- and three-dimensional ZnO nanostructures. More specifically, a thorough discussion regarding luminescence characteristics of the one-dimensional ZnO nanostructures is presented for ultraviolet and visible regions. We summarize the room temperature spontaneous emission and stimulated emission along with the interaction of the incident beam with material cavity to produce resonant optical modes and low-temperature time resolved photoluminescence studies. The most recent published results on the white light emitting diodes fabricated with the combination of ZnO nanotubes with p-GaN and ZnO nanorods with p-organic polymers on glass and disposable paper are discussed. Additionally, the significant results on optically and electrically pumped lasers are discussed; along with an overview on the future of ZnO nanostructures based photonic devices.

Synthesis and Properties of One-dimensional ZnO Nanostructures and their Integration into Dye-sensitive Solar Cells

Zinc oxide (ZnO) is a wide-band gap IIb-I compound with wurtzite crystal structure, and possesses semiconducting, pyroelectric, piezoelectric, biosafe and biocompatible properties. With these unique characteristics, ZnO becomes one of the most important nanomaterials in scientific research and applications nowadays. The diversity of ZnO nanostructures gives the promising solution to many fields of nanotechnology research, such as dye-sensitized solar cells (DSSCs). As a low-cost alternative to conventional silicon-based or TiO2-based photovoltaic, one-dimensional (1D) ZnO nanomaterials exhibit remarkable potentials and meet the clean energy demand. The aim of this review is to present a brief overview for the preparation methods and properties of 1D ZnO nanotructures and describe their integration into the DSSCs field. In the end, the perspectives of the 1D ZnO nanostructures applied in DSSCs field are introduced. Keywords: Zinc Oxide (ZnO), One-dimension (1D), Nanostructure dye-sensitive solar cell (DSSC).

Controlled Growth of one-dimensional zinc oxide nanostructures in the pulsed electrodeposition mode

Zinc oxide nanostructures are objects of study in the field of optoelectronics, solar power engineering, nanosensorics, and catalysis. For the purpose of the controlled growth of one-dimensional submicrometer zinc oxide structures in the pulsed electrodeposition mode, the effect of the pulse electrolysis parameters on the morphology of ZnO layers, their optical properties, and structural and substructural characteristics is determined using X-ray diffraction, optical spectrophotometry, and atomic-force microscopy. The possibility of fabricating arrays of ZnO nanowires with different geometrical shapes, perpendicular to the substrate surface, by varying the frequency of cathode-substrate potential pulses is shown.

Zinc Oxide Nanostructures by Solvothermal Synthesis

The synthesis, characterization, and properties of three types of one-dimensional zinc oxide nanostructures are described. They were obtained by solvothermal treatment of nanometric zinc oxide as zinc ion source (i.e., starting from pure oxide), from a mixture of the oxide with stearic acid, and from intercalated oxide in the layered nanocomposite ZnO(stearic acid)0.38. The reactions were performed at 180°C in a (1:1) ethanol/water mixture. Depending on the precursor and reaction times, morphologically homogenous phases corresponding to ZnO nanoneedles, nanorods or nanowires were obtained. Photoluminescence emissions were observed and are attributed to exciton transitions and to the presence of intrinsic defects such as oxygen and zinc interstitials. The band gap energies (Eg) were comparable to the values of bulk ZnO. The prepared nanostructures showed photocatalytic activities with respect to the degradation of methylene blue which were comparable to that of bulk zinc oxide.

Influence of growth parameters on texture of ZnO nanorods by using electrochemical deposition at low temperatures

One-dimensional zinc oxide (ZnO) nanocrystals with various textures and crystalline structures have been fabricated on indium tin oxide (ITO) substrates by using cathodic electrodeposition at 60–80°C. Five sets of parameter settings that include seed layer density, applied potential, growth temperature, deposition period, and annealing temperature, are found to vary the growth of ZnO nanorod arrays on ITO substrates. The structural transformation of as-grown ZnO nanorods is characterized by X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photon spectroscopy. The preferential textured growth (i.e., c-axis) of electrodeposited ZnO nanorods from aqueous electrolyte shows an increase with increasing deposition potential, growth temperature, deposition period, and annealing temperature. The resulting ZnO nanorods display wurzite crystal structure and the crystalline rods grow preferentially in (002) direction according to a small integral intensity ratio of (101)/(002). The spacing between adjacent lattice fringes is approximately 2.620Å, which is close to the interspacing of d002 plane. The analysis of Arrhenius-type plots provides evidence of a multiple-stage growth mechanism according to different apparent activation energies having the following order: 27.5kJ/mol (period: 5min)<41.8kJ/mol (period: 10min)<46.1kJ/mol (period: 20min) within 60–80°C. The study on the parameters affecting the ZnO texture offers significant benefit for growing the desired morphology of ZnO nanorods on conducting substrates at low temperature.

Synthesis of ZnO nanorods by the thermal reduction process of a mixture of ZnO and Al powder

AbstractSingle‐crystalline Zinc oxide (ZnO) nanorods were firstly synthesized on gold‐coated Si substrate via a simple thermal reduction method from the mixture of ZnO and Al powder. The growth process was carried out in a quartz tube at different temperature (550‐700 °C) and at different oxygen partial pressure. Their structure properties were investigated by X‐ray diffraction (XRD), scanning electron microscope (SEM), X‐ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The length of the as‐prepared ZnO nanorods was up to several micrometers and their diameters were about 130 nm. The X‐ray diffraction patterns, transmission electron microscopic images, and selective area electron diffraction patterns indicate that the one‐dimensional ZnO nanorods are a pure Single‐crystal and preferentially oriented in the [0001] direction. The reaction mechanism of ZnO nanorods was proposed on the basis of experimental data. (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Spontaneous Electrochemical Synthesis of Morphologically Controlled 1D ZnO Structure with O ∕ Zn Composition Ratio Dependent Photoluminescences

Spontaneous electrochemical synthesis of one-dimensional zinc oxide (1D ZnO) nanostructure from Zn anodes in an electrochemical cell is preliminarily demonstrated. By varying the discharged current up to , a larger amount of composites with few quantity of nucleation sites are obtained to promote an anisotropic growth of 1D ZnO nanostructure. The morphology and the size-controlled 1D ZnO structure can achieve a larger scale than others by a inducing larger quantity of near the nucleation site to promote the quick reaction. Such a reaction provides a strong and distinct narrow photoluminescent spectrum for the synthesized ZnO with (100) wurtzite structure with well crystallized and expanding grain. The room temperature photoluminescence and X-ray energy-dispersive spectra indicate that the composition-ratio varied ZnO with a zinc-rich condition as well as relatively low composition ratio is preferably obtained in KOH aqueous solution at high discharged current. Our results elucidate that the significantly decreased defect-related luminescence and enhanced bandgap UV emission is controllable via the tunable discharged current and reactive time induced optimization on the quantity of and precursors.

Preparation and characterisation of one-dimensional zinc oxide structure

One-dimensional (1D) zinc oxide (ZnO) has been synthesised using immersion technique which is a simple and inexpensive process. X-ray diffraction (XRD) showed that the obtained 1D structure was ZnO crystalline. Scanning electron microscopy (SEM) was used to investigate the morphology of 1D ZnO. Current–voltage (I–V) measurement was conducted to study electrical properties of the 1D ZnO structure.

Morphological transition of vertically aligned one-dimensional zinc oxide

Vertically aligned 1D ZnO nanostructures have been synthesized on Si (100) substrates by thermal evaporation of zinc oxide powders without using a catalyst. The morphology and size of the as-grown ZnO nanorods gradually change as the distance between the substrate and the source increases. All of the nanorods are synthesized not on the Si substrate, but on the ZnO buffer layer, which forms on Si substrate during the growth process. The as-grown ZnO nanostructures show a morphological transition from nanorods with an abrupt tip to nanorods with a blunt tip, to nanonails with a cap, and finally to ZnO quantum dots as the temperature of the Si substrate decreases.

Size- and Surface-dependent Stability, Electronic Properties, and Potential as Chemical Sensors: Computational Studies on One-dimensional ZnO Nanostructures

The structures and electronic properties of zinc oxide (ZnO) one-dimensional (1D) nanostructures, including nanowires with hexagonal or triangular cross sections, faceted nanotubes, and conventional single-walled nanotubes, were investigated using density functional theory. The binding energies and band gaps of ZnO 1D nanostructures are determined by surface atom ratios and sizes. Hydrogen passivation preserves semiconducting characteristics and further enhances the band gap of ZnO nanowires. ZnO nanowires are potential chemical sensors for dioxin.

Thermal chemical vapor deposition growth of zinc oxide nanostructures for dye-sensitized solar cell fabrication

Dye-sensitized solar cells (DSSCs) were fabricated using a quasialigned one-dimensional zinc oxide (ZnO) nanostructure. The ZnO nanostructures were grown on indium tin oxide (ITO) coated glass substrate via a thermal chemical vapor deposition (CVD). It has been considered that thermal CVD is not suitable for the growth of ZnO nanostructure on ITO/glass due to the high processing temperature. However, we have demonstrated that a densely populated ZnO nanostructure can be prepared on ITO/glass substrate by a double-source double-tube CVD process. The power conversion efficiency of our device is 0.6%.

Vapor phase synthesis of aligned ZnO nanorod arrays from elements

A vapor phase process is described for the synthesis of one-dimensional zinc oxide nanocrystal arrays. Using this process, well-aligned ZnO nanorod arrays are grown on (100) Si substrates with no catalyst. Cathodoluminescence, x-ray diffraction, and electron microscopy results demonstrate that the nanorods are characterized by high purity, stoichiometric composition, and perfect crystal structure.

Growth mechanisms of one-dimensional zinc oxide hierarchical structures

One-dimensional (1D) zinc oxide (ZnO) hierarchical structures have been self-assembled onamorphous carbons using thermal chemical vapour transport and condensation. Threetypical micro- and nanostructures consisting of micrometre-sized rods and nanometre-sizedneedles were observed. Growth mechanisms were established to elucidate the growthproperties of 1D ZnO hierarchical structures.