Zinc Oxide Nanobelts Research Articles

Spontaneous chiral self-assembly of CdSe@CdS nanorods

Spontaneous chiral self-assembly of CdSe@CdS nanorods

Size and Crystal Orientation-Dependent Thermal Behaviors of ZnO Nanobelts

We report the size and crystal orientation-dependent thermal behaviors of zinc oxide (ZnO) nanobelts revealed by transmission electron microscopy (TEM) and atomic force microscopy imaging. Direct o...

Optical study of Au/Ti/Ni/Mg-nanoparticles decorated zinc oxide heterostructures: size effect induced modulation of work function

The development of the novel semiconductor heterogeneous functional materials is playing an ever more important role in materials and efficient devices with new properties and functions. In this work, heterostructures of Au/Ti/Ni decorated zinc oxide nanobelts were synthesized. The amount and diameter of metal nanoparticles were controlled by the sputtering time or the deposition time. The photoluminescence of metal/ZnO heterostructures has been investigated. Very strong enhancement of near-band-edge emission and simultaneous attenuation of visible emission were observed for ZnO nanobelts decorated with Au, Ti and Ni nanoparticles. But both the NBEUV and DL emission intensities of Ni/ZnO heterostructures decrease dramatically initially. A novel mechanism is proposed to explain observed kinds of experimental results based on characteristic of metal nanoparticles, LSPR, Purcell effects and work function change of nanosize induced. The Mg decorated zinc oxide nanobelts were synthesized for the first time. Then the entire mechanism was testified by the investigation on Mg/ZnO and Ni/ZnO heterostructures due to its much lower and higher work functions compared with that of ZnO nanobelts, respectively. The mechanism will facilitate the technical application of metal-nanoparticles decorated heterostructures, and be very useful for the creation of highly efficient optoelectronic devices.

Field Emission from Zinc Oxide Nanobelt

Field Emission from Zinc Oxide Nanobelt

One-pot synthesis of ZnO nanowires and belts through orientation attachment mechanism

Zinc oxide (ZnO) is one of the promising materials for optoelectronics and advanced electronics-based device fabrication. Nanostructured features include further flavor to the applications as well due to inherent and unprecedented properties. With this view, a sol–gel route for the synthesis of nanostructured ZnO, such as nanoparticles, nanowires and nanobelts subsequently obtained in one-pot has been reported. The process includes synthesis of monodispersed nanoparticles that can find potential applications as gas sensing layers and transparent conducting layers. Hexagonal wurtzite crystal structure with cell constants, a = 3.2427 Ǻ and c = 5.1948 Ǻ was confirmed by X-ray diffraction. Strong preferential growth along {101} plane indicated the growth of ZnO crystallites along c-axis. Vibrational band for Zn–O stretching and deformation modes was confirmed by Fourier transform infrared absorption spectroscopy. A reasonably well-coverage of ZnO nanoparticles, ca. 1 × 107 nanoparticles/cm2 along with size distribution of (13.5 ± 9.0) nm diameter, was obtained by topographic observation of scanning electron microscopy. A series of scanning electron micrographs revealed that as-synthesized nanoparticles were further processed to obtain nanometric wires and belts under controlled conditions. The nanowires were formed from anisotropic agglomeration of nanometric particles, and the belts were formed by agglomeration of these nanometric wires into bundles. A close observation indicated that ZnO nanowires of diameter 40–50 nm were consisted of one to three constituent colloids. Control of these selective agglomeration processes is a key challenge for application of nanowires and belts into useful devices. Evolution of ZnO nanowires and nanobelts via orientation attachment mechanism of ZnO colloids.

Controllable Formation of Zinc Oxide Micro‐ and Nanostructures via DUV Direct Patterning

Various kinds of zinc oxide (ZnO) nanostructures, such as ZnO nanowires, ZnO nanobelts, ZnO nanosheets, and ZnO nanorods are promising building blocks for nanoscale systems. However, to precisely control the size, shape, and to make a controlled assembly of synthesized ZnO nanostructures are major difficulties in the development of bottom‐up devices. To overcome the challenge regarding reproducibility and positioning, a new method is proposed, deep ultra‐violet (DUV) direct photo‐patterning, to create ZnO micro‐ and nanostructures.A sol–gel formulation sensitive to DUV light and based on zinc methacrylate precursor is developed, and the photoreactions of zinc methacrylate under DUV light are carefully investigated by in situ spectroscopic ellipsometry, in situ FTIR, and XPS analysis. Then, the sol–gel solution is used as a negative tone resist in DUV lithography to evaluate its performance in producing high‐resolution patterns. The results indicate that small patterns from micro‐ to nanoscale can be obtained in a simple and direct way.

An enzyme free Vitamin C augmented sensing with different ZnO morphologies on SnO2/F transparent glass electrode: A comparative study

Three types of Zinc oxide (ZnO) nanostructures viz. ZnO nanocrystals (ZnONCs), ZnO nanoparticles (ZnONPs) and ZnO nanobelts (ZnONBs) were synthesized and characterized by UV–Vis, FTIR and SEM. A comparison of signal amplification by these ZnO nanostructures as judged by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Linear Sweep Voltammetry (LSV) revealed that ZnONCs are better sensing interface for electrochemical detection. When these ZnO nanostructure were compared electrochemically for sensing Vitamin C, ZnONC's sensor outperformed the ZnONP and ZnONB sensor and previously reported sensors. The ZnONCs/MB/FTO electrode showed a wide linear sensing range (0.001μM to 4000μM), low detection limit (0.0001μM), a small response time (5s) and a storage stability of 6months. To the best of our knowledge, this elevated sensitivity and remarkable stability for electrochemical Vitamin C detection using ZnONC's have not been reported so far.

Field Emission from Zinc Oxide Nanobelts.

We report here, the in-situ field emission (FE) property measurement on the individual ZnO nanobelts inside a high resolution transmission electron microscope (TEM) using a special scanning tunneling microscopy (STM)-TEM system. The field emission properties were found to be size scale dependent. It was found that the threshold voltage decreases and the field enhancement factor increases with the decrease in the diameter of the tip of the nanobelt and increase in the sharpness of the tip. The field emission parameter was estimated following the Fowler-Nordheim (F-N) theory. The ZnO nanobelt with the sharp agave like tip structure (d = 10 nm) showed the highest value of the field enhancement factor, β ≈ 4562, and a high field emission current of ~ 502 µA.

Buckling instability of zinc oxide nanobelts under uniaxial compression investigated using molecular dynamics

Molecular dynamics is used to simulate the phase transformation and load curves of ZnO nanobelts during a uniaxial compression process. The Buckingham-type interatomic potential is modeled to simulate the interaction between Zn and O atoms. This study focuses on the stretch process parameters, including the stretch rate and substrate temperature. Under uniaxial compressive loading, a phase transformation occurs and the critical buckling stress is computed. From the simulation results, the load-carrying capacity of a nanobelt decreases significantly with increasing slenderness ratio L/r. The buckling stress decreases with increasing substrate temperature.

Effects of Mg doping on optical and CO gas sensing properties of sensitive ZnO nanobelts

We report the synthesis, optical characterization and enhanced carbon monoxide (CO) gas sensing properties of magnesium (Mg) doped 1D zinc oxide (ZnO) nanobelts obtained via a vapor transport method.

A Study on the Field Emission Property of Zinc Oxide Nanobelts by Insitu Transmission Electron Microscopy

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Structural and catalytic properties of ZnO and Al2O3 nanostructures loaded with metal nanoparticles

Nanostructured zinc oxide (ZnO) nanobelts and aluminum oxide (Al2O3) nanoribbons have been grown successfully from the vapor phase. XRD results confirmed the purity and the high quality of the formed crystalline materials. TEM images showed that ZnO nanostructures grew in the commonly known tetrapod structure with nanobelts separated from the tetrapods with an average width range of 10–30 nm and a length of about 500 nm. Al2O3 nanostructures grew in the form of nanoribbons with an average width range of 20–30 nm and a length of up to 1 μm. The catalytic oxidation of CO gas into CO2 gas over the synthesized nanostructures is also reported. Higher catalytic activity was observed for Pd nanoparticles loaded on the ZnO nanobelts (100% conversion at 270 °C) and Al2O3 nanoribbons (100% conversion at 250 °C). The catalytic activity increased in the order Cu < Co < Au < Pd for the metal-loaded nanostructures. The preparation methods could be applied for the synthesis of novel nanostructures of various materials with novel properties resulting from the different shapes and morphologies.

Zinc oxide nanostructures and porous films produced by oxidation of zinc precursors in wet-oxygen atmosphere

Wet oxidation can be used to produce high quality zinc oxide (ZnO) nanostructures at moderately high temperatures with low requirements of equipment and experimental conditions. Zn precursor films were prepared by magnetron sputtering and controlled ZnO nanostructures were produced by oxidation of the Zn precursor films in wet O2. The growth mechanism of the ZnO nanowires and nanobelts in wet oxidation was discussed based on the experimental results. Silver and nitrogen doping were realized in the wet oxidation process, with different techniques. The structural and optical properties of the ZnO nanostructures were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL) measurements to understand the growth process of ZnO in wet oxidation. The production of ZnO porous films by wet oxidation process is also presented.

Phase transformation of stress-induced zinc oxide nanobelts using molecular dynamics

A molecular dynamic method was used to simulate the mechanical response and stretching deformation of Zn–O nanobelts under a tensile process. The Buckingham-type interatomic potential was modeled to simulate the interaction between Zn–O atoms. It focused on diverse stretch process parameters including stretch rate, and substrate temperature, and it used an atomic stress to obtain the residual stress during tensile loading. During the simulations, we found the tensile loading to create reconstruction, observed the phase transformation, and computed the residual stress. From the simulation results, the failure stresses were about 6–7.5 GPa at substrate temperatures of 300–900 K when the wurtzite (WZ) transformed into a body-centered-terragonal lattice with a four-atom ring (BCT-4), which occurred through the destruction of Zn–O bonds on the cleavable [ 0 1 1 ¯ 0 ] plane in the [0 0 0 1] loading direction.

Electronic transport properties of In-doped ZnO nanobelts with different concentration

In this paper, zinc oxide (ZnO) nanobelts with five different indium (In) concentrations (1.98, 2.73, 3.33, 4.20, and 5.16 wt%) were prepared by simple vapor deposition with HAuCl(4) (1% solution) as catalyst. Detailed structural and compositional characterizations were performed by XRD, TEM, EDS, PL, and Raman spectroscopy. Moreover, the current-voltage (I-V) characteristics of In-doped ZnO nanobelts with different In concentrations were determined by nano-manipulation and measurement systems. The results show that the resistivity of these nanobelts decreases with increasing In concentration when the doping concentration of In is lower than 4.20%, but, on the contrary, when the In concentration is higher than 4.20% their resistivity increases. Also, all of the nanobelts keep ohmic contact very well. Simultaneously, the influence of electron beam irradiation (20 kV) on the nanobelts was studied, and it was found that electron beam irradiation can improve the conductivity of the nanobelts. Under the same voltage, the current increased gradually during irradiation until equilibrium was reached. The degree of influence of the irradiation on the resistivity of the nanobelts is the greatest when the In dopant concentration is 4.20%, which is suitable for making irradiation sensors.

High-yield synthesis of single-crystalline zinc oxide nanobelts and their applications in novel Schottky solar cells

High-quality ZnO nanobelts were synthesized through introducing an unsteady state in the vapour transport process and their applications in novel Schottky solar cells were demonstrated by contact-printing the ZnO nanobelt network onto a pre-patterned Pt electrode followed by the deposition of a Ti/Au electrode.

Electrical Self-Healing of Mechanically Damaged Zinc Oxide Nanobelts

We report the observation of remarkable electrical self-healing in mechanically damaged ZnO nanobelts. Nanoindentation into intrinsically defect-free ZnO nanobelts induces deformation and crack damage, causing a dramatic electrical signal decrease. Two self-healing regimes in the nanoindented ZnO nanobelts are revealed. The physical mechanism for the observed phenomena is analyzed in terms of the nanoindentation-induced dislocations, the short-range atomic diffusion in nanostructures, and the local heating of the dislocation zone in the electrical measurement.

STRUCTURAL, OPTICAL AND GAS SENSING PROPERTIES OF ZnO, SnO2 AND ZTO NANOSTRUCTURES

Tetrapods, nanobelts and polyhedron-shape like zinc oxide (ZnO) , tin dioxide (SnO2) nanostructures and ZnO/ZnSnO3/Zn2SnO4 (ZTO) composite functional semiconducting nanostructures have been synthesized successfully by the vapor–solid growth process. XRD analyses showed that ZnO with wurtzite, SnO2 with rutile and zinc stannate (ZnSnO3) and/or dizinc stannate (Zn2SnO4) with polyhedral crystal structure were condensed from the vapor phase when Zn and/or Sn metal powders individually or mixed were used as the starting materials. The driving forces for growth of these nanostructures were found to be vapor density, temperature, pressure and place of deposition from the source materials. Typically, the ZnO nanobelts have lengths of several hundred of nanometers and widths of about 10–15 nm. The average particle size of SnO2 are in the range of about 10–20 nm. Uniform hexagonal-shaped crystals of ZnO/ZnSnO3/Zn2SnO4 composite in the range of 50–300 nm as estimated from TEM images are observed. Based on the TEM, optical absorption and emission studies and the CO gas sensing characteristics of the prepared materials showed good crystal quality implying that the ZnO , SnO2 and ZnO/ZnSnO3/Zn2SnO4 nanostructures may suggest possible applications in optoelectronic devices and chemical gas sensors.

National engineers week: Reaching out to the engineers of the future

Nanoaccelerometers, embedded within sewer pipes, use a weighted silicon shaft to determine changes in wastewater flow. Roadways incorporate solar thin films to provide an additional energy source to a city. A zinc oxide nanobelt coated with multilayer polymers monitors temperatures within a lunar colony’s synthetic atmosphere. As sophisticated as these concepts are, you won’t find them on the drawing boards of any cutting-edge laboratories. Instead, try the imaginations of middle school students who discovered the creativity and excitement of engineering in the National Engineers Week Future City Competition last year. For 2009, more than 30,000 students, working with volunteer engineer-mentors, are focusing on conserving and reusing water. Since January, they have been presenting their solutions, designs, and models at regional competitions, with the winners heading to Washington D.C. for the 17th annual Future City National Finals during National Engineers Week, February 16–18. While Future City is a complex, nationally coordinated initiative, many notable Engineers Week efforts are of the grassroots variety. The Illinois Institute of Technology in Wheaton, for instance, is opening its doors to the community on February 21 for its annual Engineers Week Expo. Staffed by volunteers from local engineering societies, educational institutions, and businesses, the Expo features interactive displays and presentations designed to show how math and science impact everyday life. Other organizations take a more individualized approach by participating in such Engineers Week activities as Introduce a Girl to Engineering Day on February 19. A National Engineers Week: Reaching out to the Engineers of the Future

Up‐ and Down‐Conversion Cubic Zirconia and Hafnia Nanobelts

One-dimensional (1D) metal oxide nanomaterials, such as zinc oxide (ZnO) nanowires and nanobelts (or nanoribbons), have recently attracted immense attention due to their sizeand shape-dependent optical, mechanical, and electronic properties. In stark contrast, investigations of 1D zirconia (ZrO2) and hafnia (HfO2) nanomaterials remain unexploited largely because of the formidable challenges associated with the fabrication of these structures with controlled dimensions and crystal phases. ZrO2 and HfO2 materials typically exhibit three primary polymorphs (monoclinic, tetragonal, and cubic) and have important technological applications as catalyst supports, oxygen detectors, hightemperature fuel cell electrolytes, gate dielectric in metaloxide semiconductor devices, and optical waveguides. Apart from a few rare examples of rod-like polycrystalline structures formed via porous alumina templates or by using an inverse microemulsion technique, most of the ZrO2 nanomaterials obtained thus far are best classified as nanoparticles and thin films. Here, we introduce a direct and scalable approach, based upon a thermal decomposition method under normal atmospheric pressure, for growing well-defined single-crystalline cubic ZrO2 and HfO2 nanobelts with controllable structural compositions and novel optical properties. To the best of our knowledge, these nanomaterials provide the first evidence of ZrO2 and HfO2 crystals with belt-like morphology. In a typical synthesis of the ZrO2 precursors, a solution of ZrCl4 (1.6 g, 7 mmol) and YCl3 6H2O (0.3 g, 1 mmol) in ethanol (10mL) was first treated with sodium hydroxide (1.5 g, 38 mmol) to yield a viscous gel mixture. The mixture was transferred into a 15mL Teflon-lined autoclave and heated at 140 8C for 24 h. Upon cooling the resulting precipitate was