Growth Of ZnO Nanotubes Research Articles

Screw-dislocation-driven growth of ZnO nanotubes seeded by self-perpetuating spirals during hydrothermal processing

We report the effects of precursor concentration on the characteristics of ZnO nanostructures during hydrothermal processing. Self-perpetuating surface spirals are fabricated at concentrations of 0.25 and 0.5 M, with samples grown at concentrations of 0.05 and 0.125 M exhibiting ZnO nanorods. This can be explained by a change in the growth mode from an initial columnar growth to a screw-dislocation-driven growth with decreased supersaturation. The screw dislocations nucleate at the V-shaped valleys of the columnar boundaries during the intermediate stage. We demonstrate that continuous screw-dislocation-driven growth leads to the formation of ZnO nanotubes having Burger’s vectors of 1.45 nm.

Growth, Structural and Optical Characterization of ZnO Nanotubes on Disposable-Flexible Paper Substrates by Low-Temperature Chemical Method

We report the synthesis of vertically aligned ZnO nanotubes (NTs) on paper substrates by low-temperature hydrothermal method. The growth of ZnO NTs on the paper substrate is discussed; further, the structural and optical properties are investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and cathodoluminescence (CL), and it was found that the ZnO NTs on paper substrate fulfill the structural and optical properties of ZnO NTs grown on other conventional substrates. This will be more beneficial in future usage of ZnO NTs in different fields and applications. Particularly, this approach opens the ways in research and development for high volume manufacturing of low-cost, flexible optoelectronics devices on disposable paper substrates and can be used in the future miniaturization trends.

Morphology-controllable ZnOnanotubes and nanowires: synthesis, growth mechanism and hydrophobic property

Controlled growth of nanostructures has long been regarded as one of the biggest obstacles to their commercial applications. Herein we demonstrate the feasibility of controlling growth of ZnO nanotubes and nanowires by floating substrates on the surfaces of reacting solutions with different concentrations, a key factor for differential growth. These slim ZnO nanotubes with outer diameters of 26.6 ± 12.2 nm and inner diameters of 8.3 ± 6.2 nm (confidence level of 95%) are a recently discovered new class of nanostructures whose growth is driven by screw dislocations (S. A. Morin et al., Science2010, 328, 476–480). Concentrations of precursors below 0.5 mmol L−1 adequately allow the slow relocation of solute clusters and spontaneous formation of the single crystal tube while the concentrations above 15 mmol L−1 induce high-speed deposition of newly forming solute clusters and fast growth of nanowires; therefore the concentration plays a crucial role in determining the morphology of one dimensional (1D) ZnO nanostructures. Furthermore, the ZnO nanotube surface, which apparently displays smaller dimension and lower density of nanostructures, exhibits improved hydrophobic property compared to the ZnO nanowire surface. The large scale controlled growth of arrays with different 1D ZnO nanostructures should be essential for fabricating novel devices and exploring advanced applications.

ZnO Nanotubes Grown at Low Temperature Using Ga as Catalysts and Their Enhanced Photocatalytic Activities

We report the synthesis of ZnO nanotubes grown via the Ga-catalyzed vapor transport method at low temperature and their photocatalytic activity. The low melting point of Ga (29 °C) resulted in the growth of ZnO nanotubes at a low temperature of 80 °C, enabling us to use Kapton film or ITO glass as substrates. Structure analysis shows that the nanotube is single crystal and has a hollow structure with a wall thickness of ∼2 nm, is several tens of micrometers long, and has a diameter of 60-300 nm. Photocatalytic activity of ZnO nanotubes was determined by measuring the photoinduced degradation of rhodamine B (RB) and an azobenzene-containing polymer poly{1-4[4-(3-carboxy-4-hydroxyphenyl-azo)benzenesulfonamido]-1,2- ethanediyl sodium salt} (PAZO) solution, respectively. The measurement reveals that the photodecomposition reactions of both RB and PAZO follow the first-order rate law with the rate constant of 0.018 and 0.004 s ―1 , respectively. The photocatalytic activity of ZnO nanotubes was shown to be much enhanced compared with ZnO thin films and ZnO nanowires. Therefore, this work demonstrates a novel and simple way to synthesize ZnO nanotubes on flexible substrates, which can potentially serve as excellent photocatalysts for the degradation of organic pollutants in water.

ZnO Nanotube Ethanol Gas Sensors

This investigation reports on the growth of ZnO nanotubes on patterned templates by reactive evaporation and the fabrication of a ZnO nanotube ethanol gas sensor. The as-grown ZnO nanotubes were polycrystalline and had holes at their terminals and sidewalls. Injection of ethanol gas reduced the resistivity of the fabricated sensor. Introducing 100 ppm ethanol gas increased the measured sensitivities of the ethanol gas sensors from 34 to 87% as the temperature increased from 90 to . Additionally, the sensitivity of the sensor increased with the concentration of injected ethanol gas.

Growth of Single Crystalline ZnO Nanotubes and Nanosquids

ABSTRACTThe growth of ZnO nanotubes and nanosquids is obtained by conventional thermal chemical vapor deposition (CVD) without the use of catalysts or templates. Characterization of these ZnO nanostructures was conducted by X-ray powder diffraction (XRD), Field-emission scanning electron microscopy (FESEM), Raman spectroscopy, and photoluminescence (PL). Results indicate that these ZnO nanostructures maintain the crystalline structures of the bulk wurtzite ZnO crystals. Our results show that rapid cooling can be used to induce the formation of ZnO nanotubes and ZnO nanosquids. The self-assembly of these novel ZnO nanostructures are guided by the theory of nucleation and the vapor-solid crystal growth mechanism.