Zinc Oxide Nanotubes Research Articles

Получение и исследование нанотрубок оксида цинка

Получение и исследование нанотрубок оксида цинка

Double Walled Gallium–Nitride and Zinc-Oxide Nanotube as a Cylindrical Nano Capacitor

Double Walled Gallium–Nitride and Zinc-Oxide Nanotube as a Cylindrical Nano Capacitor

Rapid Growth of Zinc Oxide Nanotube-Nanowire Hybrid Architectures and Their Use in Breast Cancer-Related Volatile Organics Detection.

A simple direct method for the rapid fabrication of zinc oxide nanotube-nanowire hybrid structure in an environmentally friendly way is described here. Zinc foils were anodized in an aqueous solution of washing soda and baking soda at room temperature in order to obtain the hybrid architecture. At the beginning of the process nanowires were formed on the substrate. The wider nanowires transformed into nanotubes in about a minute and grew in length with time. The morphological integrity was maintained upon heat treatment at temperatures up to the melting point of the substrate (∼400 °C) except that the nanotube wall became porous. The chemiresistor devices fabricated using the heat-treated structure exhibited high response to low-concentration volatile organic compounds that are considered markers for breast cancer. The response was not significantly affected by high humidity or presence of hydrogen, methane, or carbon dioxide. The devices are expected to find use as breath sensors for noninvasive early detection of breast cancer.

Structural, Electronic, Vibrational, and Topological Analysis of Single-Walled Zinc Oxide Nanotubes

Single-walled armchair and zigzag ZnO nanotubes (SWZnONTs) have been studied via periodic computational simulations based on density functional theory with the B3LYP, HSE06, PBE0, and PWGGA functional and all-electron basis set. The influence of the diameter of the nanotubes was carried out with respect to the bond length (Zn–O), bond angles (Zn–O–Zn), energy strain, band gap, density of states (DOS), band structures, vibrational analysis, and topological analysis of the electron density according to the quantum theory of atoms in molecules applied to the solid state. Its nanotubes properties were compared with the ZnO bulk and (0001) monolayer surface. The topological analysis, infrared and Raman spectra, and its vibrational modes at increasing diameter are reported for the first time. Owing to these analysis, both chiralities with large diameter can be used interchangeably in semiconductor applications. These theoretical models can be extended to study further issues, such as the effects caused by the addition of dopant and the interaction of molecules inside and/or outside of the nanotube.

Periodic density functional theory study of structural and electronic properties of single-walled zinc oxide and carbon nanotubes

Periodic density functional theory calculations with the B3LYP hybrid functional and all-electron Gaussian basis set were performed to simulate the structural and electronic properties as well as the strain and formation energies of single-walled ZnO nanotubes (SWZnONTs) and Carbon nanotubes (SWCNTs) with different chiralities as functions of their diameters. For all SWZnONTs, the band gap, strain energy, and formation energy converge to ~4.5eV, 0.0eV/atom, and 0.40eV/atom, respectively. This result suggests that the nanotubes are formed more easily from the surface than from the bulk. For SWCNTs, the strain energy is always positive, while the formation energy is negative for armchair and zigzag nanotubes, therefore suggesting that these types of nanotubes can be preferentially formed from the bulk. The electronic properties of SWCNTs depend on the chirality; all armchair nanotubes are metallic, while zigzag and chiral nanotubes can be metallic or semiconducting, depending on the n and m vectors.

Graphene/CuS/ZnO hybrid nanocomposites for high performance photocatalytic applications

We herein report a novel, high performance ternary nanocomposite composed of Graphene doped with nano Copper Sulphide and Zinc Oxide nanotubes (GCZ) for photodegradation of organic pollutants. Investigations were made to estimate and compare the Methyl Orange dye (MO) degradation using GCZ, synthesized pristine Graphene (Gr) and Graphene–ZnO hybrid nanocomposite (GZ) under UV light irradiations. The synthesis of nanocomposites involves the simple ultra-sonication and mixing methods. The nanocomposites were characterized using transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Raman spectroscopy, UV–vis absorption spectroscopy and Brunauer–Emmett–Teller (BET) surface area method. The as synthesized GCZ shows better surface area, porosity and band gap energy than as synthesized Gr and GZ. The photocatalytic degradation of methyl orange dye follows as Gr <<< GCZ >> GZ due to the stronger adsorbability, large number of photo induced electrons and highest inhibition of charge carrier's recombination of GCZ. The kinetic investigation demonstrates that dye degradation exhibit the pseudo first order kinetic model with rate constant 0.1322, 0.049 and0.0109 min−1 corresponding to GCZ, GZ and Gr. The mechanism of dye degradation in presence of photocatalyst is also discussed. This study confirms that GCZ is a more promising material for high performance catalytic applications especially in the dye waste water purification.

QM/MM Study of Double Walled Zinc Oxide Nanotube (DWZnONTs) for Cylindrical Nano Capacitor Application

QM/MM Study of Double Walled Zinc Oxide Nanotube (DWZnONTs) for Cylindrical Nano Capacitor Application

Encapsulated β-carotene in ZnO nanotubes: Theoretical insight into the stabilization dynamics

The stabilization dynamics of a molecular dye (β-carotene) encapsulated in single-wall zinc oxide nanotubes (ZnONTs) is theoretically investigated in the scope of molecular dynamics and density functional theory simulations. Our findings show that the β-carotene encapsulation in ZnONTs is an energetically favorable process. Once encapsulated, this molecular dye remains close to the ZnONT wall, in accordance with recent experimental reports. Interestingly, the interaction between the β-carotene and ZnONT can form a charge delocalization state, where an amount of charge concentrated on β-carotene is transferred to ZnONT.

A facile synthesis of zinc oxide/multiwalled carbon nanotube nanocomposite lithium ion battery anodes by sol–gel method

Free standing zinc oxide (ZnO) and multiwalled carbon nanotube (MWCNT) nanocomposite materials are prepared by a sol gel technique giving a new high capacity anode material for lithium ion batteries. Free-standing ZnO/MWCNT nanocomposite anodes with two different chelating agent additives, triethanolamine (TEA) and glycerin (GLY), yield different electrochemical performances. Field emission gun scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectrometer (EDS), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analyses reveal the produced anode electrodes exhibit a unique structure of ZnO coating on the MWCNT surfaces. Li-ion cell assembly using a ZnO/MWCNT/GLY free-standing anode and Li metal cathode possesses the best discharge capacity, remaining as high as 460 mAh g−1 after 100 cycles. This core–shell structured anode can offer increased energy storage and performance over conventional anodes in Li-ion batteries.

Value of phagocyte function screening for immunotoxicity of nanoparticles in vivo.

Nanoparticles (NPs) present in the environment and in consumer products can cause immunotoxic effects. The immune system is very complex, and in vivo studies are the gold standard for evaluation. Due to the increased amount of NPs that are being developed, cellular screening assays to decrease the amount of NPs that have to be tested in vivo are highly needed. Effects on the unspecific immune system, such as effects on phagocytes, might be suitable for screening for immunotoxicity because these cells mediate unspecific and specific immune responses. They are present at epithelial barriers, in the blood, and in almost all organs. This review summarizes the effects of carbon, metal, and metal oxide NPs used in consumer and medical applications (gold, silver, titanium dioxide, silica dioxide, zinc oxide, and carbon nanotubes) and polystyrene NPs on the immune system. Effects in animal exposures through different routes are compared to the effects on isolated phagocytes. In addition, general problems in the testing of NPs, such as unknown exposure doses, as well as interference with assays are mentioned. NPs appear to induce a specific immunotoxic pattern consisting of the induction of inflammation in normal animals and aggravation of pathologies in disease models. The evaluation of particle action on several phagocyte functions in vitro may provide an indication on the potency of the particles to induce immunotoxicity in vivo. In combination with information on realistic exposure levels, in vitro studies on phagocytes may provide useful information on the health risks of NPs.

Electrochemical Deposition of ZnO Nanotubes with Small Dimples on the External Surface

To improve the photoelectric conversion efficiency of dye-sensitized solar cells, various semiconductor oxides, including zinc oxide (ZnO) and titanium oxide (TiO2), have been studied as photo electrodes. ZnO generally possesses better electron conductivity than TiO2, although TiO2 is one of the best substrate for the stable loading of dye molecules due to the strength of the dye-TiO2 chemical interaction. Therefore, it is important to improve the ZnO loading performance without diminishing its electron conductivity. ZnO nanotubes are known to exhibit high surface area and high conductivity. Recently, we focused our research on the high density ZnO nanotubes prepared by one-step electrodeposition at moderate temperature (<100 °C). Since the surface of the oxide semiconductor plays a significant role for loading the dye molecules, we report how the deposition conditions influence the surface morphology of the one-step electrodeposited ZnO.

Flexible piezoelectric energy nanogenerator based on ZnO nanotubes hosted in a polycarbonate membrane

Highly oriented zinc oxide (ZnO) nanotubes were synthesized in a porous polycarbonate (PC) matrix, leading to a highly flexible ZnO–PC composite able to work as efficient energy nanogenerator. The crystalline direction of the ZnO c-axis is obtained parallel to the membrane surface, thus advantageous for the exploitation of composite under bending stresses. Three different pore sizes of the templating PC membranes were successfully employed, i.e., having nominal pore diameter 30, 50 and 100nm, thus obtaining three different ZnO one-dimensional nanostructures supported into the PC membrane. The ZnO–PC nanogenerators were successfully tested both under compressive and bending strains, showing an influence of the ZnO nanotube size on the output voltage. Using the 100nm pore PC membrane, a maximum output voltage of 1.15V, a maximum current of 100μA and a maximum output power density of 287.5mW/cm3 were reached, being these values among the highest reached in zinc oxide-based piezoelectric nanogenerators. Such remarkable results make the nanostructured ZnO–PC composite a promising material for energy harvesting applications.

Low temperature carving of ZnO nanorods into nanotubes for dye-sensitized solar cell application

High aspect ratio zinc oxide (ZnO) nanotubes (NT) were synthesized based on a two-steps approach. In the first step, ZnO nanorod (NR) arrays were prepared by chemical bath deposition from an aqueous of zinc nitrate. In the second step, the cores of ZnO NRs were carved selectively in a KCl solution, resulting in the formation of a tubular structure. The influence of KCL concentration, temperature, and immersion time on the ZnO NT formation process was completely characterized and investigated. 12.5μm NRs and NTs have been utilized to manufacture dye-sensitized solar cells (DSSCs) and as a result, conversion efficiencies of 1.06% and 2.87% were obtained, respectively. Electrochemical impedance spectroscopy measurements have demonstrated that the NTs could acquire a higher electron lifetime compared to NRs which causes a faster electron collection. The overall improvement in NT-based DSSC performance demonstrates a new approach to enhance the efficiency of dye-sensitized solar cells.

Stability of Disperse Systems during Bioassay of Nanoecotoxicity with Use of Aquatic Organisms

The paper is devoted to studying the stability of of dispersed systems (DS) of nanoparticles (NP) of nickel (nNi), platinum (nPt), titanium dioxide (nTiO2), zinc oxide, multicomponent nanopowder (MNP) and multi-walled carbon nanotubes (MWCNT), formed basing on the growth media used in bioassay with application of aquatics: bacterial test-cultures Ecolum, Photobacterium phosphoreum and Escherihia coli, unicellular algae Chlorella vulgaris Beijer, infusoria Paramecium caudatum, cladocera Daphnia magna Straus and Ceriodaphnia affinis, fish Danio rerio. In the process of establishing a test-system the increase in the initial nanosubstance concentration of more than 5 mg/l results in the increase in the speed of aggregation of NP into DS and the decrease in their final concentration. We suggest the variants of estimation of effective concentration of NP in long-term biotesting.

Nanomaterials and neurodegeneration.

The increasing application of nanotechnology in various industrial, environmental, and human settings raises questions surrounding the potential adverse effects induced by nanosized materials to human health, including the possible neurotoxic and neuroinflammatory properties of those substances and their capability to induce neurodegeneration. In this review, a panel of metal oxide nanoparticles (NPs), namely titanium dioxide, silicon dioxide, zinc oxide, copper oxide, iron NPs, and carbon nanotubes have been focused. An overview has been provided of the in vitro and in vivo evidence of adverse effects to the central nervous system. Research indicated that these nanomaterials (NMs) not only reach the brain, but also can cause a certain degree of brain tissue damage, including cytotoxicity, genotoxicity, induction of oxidative stress, and inflammation, all potentially involved in the onset and progression of neurodegeneration. Surface chemistry of the NMs may play an important role in their localization and subsequent effects on the brain of rodents. In addition, NM shape differences may induce varying degrees of neurotoxicity. However, one of the potential biomedical applications of NMs is nanodevices for early diagnostic and novel therapeutic approaches to counteract age related diseases. In this context, engineered NMs were promising vehicles to carry diagnostic and therapeutic compounds across the blood-brain barrier, thereby representing very timely and attractive theranostic tools in neurodegenerative diseases. Therefore, a careful assessment of the risk-benefit ratio must be taken into consideration in using nanosized materials.

An Experimental Investigation into the Thermal Properties of Nano Fluid

In this paper, the results of the experimental investigation on the thermal properties of Nano fluid are presented. The effect of sonication time, settling time and temperature on the thermal conductivity, viscosity and specific heat of zinc oxide (ZnO, 14 nm and 25 nm size) and single walled carbon nanotube (SWCNT, 10nm size) based Nano fluid are investigated and the results of ZnO with DI water and ethylene glycol (EG) as base fluids are compared. The experimental results indicate that the studied parameters have a remarkable effect on the thermal properties of Nano fluid. The rate of enhancement in thermal conductivity of EG based Nano fluid is found to be less than that of water based Nano fluid. The SWCNT based DI water Nano fluid found to be very unstable i.e. the nanoparticles settle down very rapidly. The 0.02% volume fraction of SWCNT nanoparticles suspension results in 10% increase in the specific heat of DI water. A decrement of 24% and 13% in the specific heat of 14 nm size ZnO based Nano fluid were obtained at a volume fraction of 0.001% and 0.002% respectively.

Effect of structural defects on the hydrogen adsorption in promising nanostructures

Hydrogen adsorption in various nanosystems is one of the well studied topics of interest, due to its significance for the automobile applications. Scientists are considering novel nanostructures to enhance the storage capacity of hydrogen through various mechanisms and adsorption is one of the important process for this purpose. Here, we are interested in the structural aspects of some of emerging and promising nanostructures like carbon nanotube (CNT), zinc oxide nanotube (ZnONT) and silicon carbide nanotube (SiCNT) for hydrogen adsorption and storage. A set of three nanotubes for the above materials are considered and each type consists of three tubes of same diameter but different chirality. Density functional theory (DFT) based calculations are performed in both defected and defect free tubes for complete analysis. We could observe a strong role of defect in SiC and CNT but less effect in ZnO for the hydrogen adsorption phenomena. We could observe the two fold binding energy in defected armchair SiC and chiral CNT than defect free materials. A considerable change in HOMO-LUMO band gap (Eg) is observed in three nanotubes.

Zinc Oxide Nanostructures Formed by Wet Oxidation of Zn Foil

Zinc oxide (ZnO) nanostructures were successfully grown by wet oxidation of zinc (Zn) foil in water at 90 °C for 2 to 8 h. The effect of etching the Zn foil before oxidation treatment on the morphology of ZnO nanostructures was investigated. Hemispherical structures of ZnO nanowires, nanorods and nanotubes were produced on etched Zn foil at different oxidation times. The growth of hemispherical structures was possibly due to the formation of pits along the grains after etching. Without etching, relatively aligned nanorods were formed after wet oxidation with the structure becoming coarser after longer oxidation time. The anisotropic growth ZnO nanostructures on the surface of Zn foil by wet oxidation could be due to the inherent growth habit of ZnO crystal.

Novel rapid synthesis of zinc oxide nanotubes via hydrothermal technique and antibacterial properties

ZnO nanotubes with the wurtzite structure have been successfully synthesized via simple hydrothermal solution route using zinc nitrate, urea and KOH for the first time. The structural, compositions and morphology architectures of the as synthesized ZnO nanotubes was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and high resolution transmission scanning electron microscopy (HRTEM). TEM showed that ZnO nanotubes exhibited a wall thickness of less than 2nm, with an average diameter of 17nm and the length is 2μm. In addition, the antibacterial activity of ZnO nanotubes was carried out in vitro against two kinds of bacteria: gram - negative bacteria (G −ve) i.e. Escherichia coli (E. coli) and gram – positive bacteria (G +ve) i.e. Staphylococcus aureus. Therefore, this work demonstrates that simply synthesized ZnO nanotubes have excellent potencies, being ideal antibacterial agents for many biomedical applications.

Electrochemical Deposition of Zinc Oxide Nanotubes with Countless Small Dimples on the External Surface

1. Introduction For the improvement of photoelectric conversion efficiency of dye-sensitized solar cells, oxide semiconductors of different shapes have been developed for utilization as photo-electrode. Then, many studies suggested that the surface of oxide semiconductor play a significant role for loading the dye. Among various oxide semiconductors, titanium oxide (TiO2) is known to be one of the best substrate for loading a large amount of dye stably from the perspective of the strength of chemical interaction, while zinc oxide (ZnO) is known to possess better electron conductivity than TiO2. From this point of view, hybrid material of TiO2 and ZnO has been actively studied. For the both hybrid system and solely use of ZnO, the optimization of surface morphology of ZnO is considered to be required to improve the immobilization condition, including the amount and the stability, of dye without loosing its good conductivity. Recently, Ellah et al. reports electrochemical one step deposition of ZnO nanotube on indium tin oxide (ITO) substrate [1]. This method is interesting because nanotubes, which is one of the shapes possessing high surface area and good electron conductivity, can be deposited with high density within one hour at moderate temperature (< 100 °C). In this study, we investigate on the influence of several deposition conditions on the morphology of ZnO with much attention to the surface, by using fluorine-doped tin oxide (FTO) as a substrate.2. Experimental The FTO glass surface were clarified in a mix solution of deionized water, acetone, and 2-propanol (1: 1: 1), by using ultrasonic cleaner. For the electrochemical deposition, three-electrodes cell was used in which, working electrode is the FTO glass, reference electrode is Ag/AgCl, counter electrode is Pt wire electrode. The electrolyte contained 0.5mM ZnCl2and 0.1 M KCl in deionized water and that bubbled 30 minutes with oxygen beforehand electrochemical deposition. As deposition conditions, 60 minutes, 70℃, -1.0V (vs. Ag/AgCl)- (a) is utilized as standard, and the effect of the time, temperature, and deposition potential on the shape of the ZnO were carefully investigated mainly by scanning electron microscope (SEM).3. Results and discussion The deposition of nanotubes, which have hexagonal structure, was confirmed on the FTO substrate by SEM at various preparation conditions. And, it was revealed that the deposition time is proportion to the length of the nanotube, the temperature is proportion to the both length and the diameter as similar to the previous report [1]. In particular, nanotubes with countless small dimples on the external surface, which is expected to increase surface area, was observed by the SEM at the condition of 60 minutes, 70℃, -0.7V. The length and the diameter of this nanotube are 1.0 µm and 0.2 µm, respectively. And, the countless small dimples are about 10 nm (Fig.1). In the presentation, the effect of these surface morphologies on the photoelectric conversion efficiency will be also discussed.[1] M. A. Ellah et al., “Effect of Electrolyte Conductivity on Controlled Electrochemical Synthesis of Zinc Oxide Nanotubes and Nanorods,” J. Phys. Chem. C 2013, 117 6794-6799.