Carbon Nanowires Research Articles

Single‐Layered Ultrasmall Nanoplates of MoS2 Embedded in Carbon Nanofibers with Excellent Electrochemical Performance for Lithium and Sodium Storage

AbstractThe preparation and electrochemical storage behavior of MoS2 nanodots—more precisely single‐layered ultrasmall nanoplates—embedded in carbon nanowires has been studied. The preparation is achieved by an electrospinning process that can be easily scaled up. The rate performance and cycling stability of both lithium and sodium storage were found to be outstanding. The storage behavior is, moreover, highly exciting from a fundamental point of view, as the differences between the usual storage modes—insertion, conversion, interfacial storage—are beneficially blurred. The restriction to ultrasmall reaction domains allows for an almost diffusion‐less and nucleation‐free “conversion”, thereby resulting in a high capacity and a remarkable cycling performance.

Використання курячих ембріонів для визначення біологічних ефектів, спричинених дією азбесту та вуглецевих нановолокон

The apparent structural link between carbon nanowires and asbestos fibers has generated serious doubts about their safety profile. Until today data on asbestos concerns researches mostly of respiratory system. Therefore we used a chicken embryo because it enables to evaluate the body's reaction to materials on a large number of cell population. The results show that the straight fiber asbestos (amphibole) poses the greatest danger. Also our research demonstrate that carbon nanowires have the potential to behave like amphibole asbestos fibers.

Fluorescent carbon nanowires made by pyrolysis of DNA nanofibers and plasmon-assisted emission enhancement of their fluorescence.

We report on a facile method for preparing fluorescent carbon nanowires (CNWs) with pyrolysis of highly aligned DNA nanofibers as carbon sources. Silver nanoparticle (AgNP)-doped CNWs were also produced using pyrolysis of DNA nanofibers with well-attached AgNPs, indicating emission enhancement assisted by localized plasmon resonances.

Carbon Nanofibers from Carbon Nanotubes by 1.2 keV Ar+ Sputtering at Room Temperature

Multi‐walled carbon nanotubes (MWCNTs) were irradiated by 1.2 keV Ar ion beams for 15–60 min at room temperature with current density of 60 µA/cm2. The morphology and microstructure are investigated by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that carbon nanofibers are achieved after 60 min ion irradiation and the formation of carbon nanofibers proceeds through four periods, carbon nanotubes—amorphous carbon nanowires—carbon nanoparticles along the tube axis—conical protrusions on the nanoparticles surface—carbon nanofibers from the conical protrusions.

Persistence Length as a Metric for Modeling and Simulation of Nanoscale Communication Networks

This paper explores the significance of persistence length in modeling and simulation of nanoscale networks. Persistence length, used by chemists and biologists, pertains to a wide range of high-aspect ratio, small-scale materials, and has a significant impact on communication at the nanoscale. For example, it applies to carbon nanotubes, microtubules, DNA, and nanowires as well as many other potential nanoscale network structures. Consider the similarities between microtubules in living cells and carbon nanotubes (CNTs). Both microtubules and carbon nanotubes have similar geometric structures and share similar properties; both are capable of transporting information at the nanoscale. Microtubules and carbon nanotubes can also self-organize to create random graph structures, which can be used as communication networks. At the same time, networks of CNTs may be used for molecular-level transport in the human body supporting treatment of diseases. This paper examines fundamental properties of network topologies created by filamentous structures and their relationship to the performance of nanoscale communication networks. This behavior depends strongly on the alignment of bond segments and filaments, which in turn depends on the persistence length of the tubes. We use graph spectral analysis for analyzing a simulated generic network of filamentous structures. A network graph is extracted from the layout of such a structure and graph properties of the resultant graph are examined. The paper presents the results of the simulation with tubes of different persistence lengths and makes the case for including persistence length as a parameter in standards for nanoscale communications. Our simulation results show that at different persistence lengths the network structure and the resultant properties of the graph structure that impact nanoscale communications can be predicted and analyzed. Such standard parameters help in calibrating an analytical model to a physical network allowing for synchronization between analytical and experimental results.

Sharpening the surface of magnetic paranematic droplets.

In a non-uniform magnetic field, the droplets of colloids of nickel nanorods and nanobeads aggregate to form a cusp at the droplet surface not deforming the entire droplet shape. When the field is removed, nanorods diffuse away and the cusp disappears. Spherical particles can form cusps in a similar way, but they stay aggregated after the release of the field; finally, the aggregates settle down to the bottom of the drop. The X-ray phase contrast imaging reveals that nanorods in the cusps stay parallel to each other without visible spatial order of their centers of mass. The formation of cusps can be explained with a model that includes magnetostatic and surface tension forces. The discovered possibility of controlled assembly and quenching of nanorod orientation under the cusped liquid surface offers vast opportunities for alignment of carbon nanotubes, nanowires and nanoscrolls, prior to spinning them into superstrong and multifunctional fibers. Magnetostatic and electrostatic analogies suggest that a similar ideal alignment can be achieved with the rod-like dipoles subject to a strong electric field.

Monolithic carbon structures including suspended single nanowires and nanomeshes as a sensor platform

With the development of nanomaterial-based nanodevices, it became inevitable to develop cost-effective and simple nanofabrication technologies enabling the formation of nanomaterial assembly in a controllable manner. Herein, we present suspended monolithic carbon single nanowires and nanomeshes bridging two bulk carbon posts, fabricated in a designed manner using two successive UV exposure steps and a single pyrolysis step. The pyrolysis step is accompanied with a significant volume reduction, resulting in the shrinkage of micro-sized photoresist structures into nanoscale carbon structures. Even with the significant elongation of the suspended carbon nanowire induced by the volume reduction of the bulk carbon posts, the resultant tensional stress along the nanowire is not significant but grows along the wire thickness; this tensional stress gradient and the bent supports of the bridge-like carbon nanowire enhance structural robustness and alleviate the stiction problem that suspended nanostructures frequently experience. The feasibility of the suspended carbon nanostructures as a sensor platform was demonstrated by testing its electrochemical behavior, conductivity-temperature relationship, and hydrogen gas sensing capability.

Influence of spatial configurations on electromagnetic interference shielding of ordered mesoporous carbon/ordered mesoporous silica/silica composites

Ordered mesoporous carbons (OMCs), obtained by nanocasting using ordered mesoporous silicas (OMSs) as hard templates, exhibit unique arrangements of ordered regular nanopore/nanowire mesostructures. Here, we used nanocasting combined with hot-pressing to prepare 10 wt% OMC/OMS/SiO2 ternary composites possessing various carbon mesostructure configurations of different dimensionalities (1D isolated CS41 carbon nanowires, 2D hexagonal CMK-3 carbon, and 3D cubic CMK-1 carbon). The electric/dielectric properties and electromagnetic interference (EMI) shielding efficiency (SE) of the composites were influenced by spatial configurations of carbon networks. The complex permittivity and the EMI SE of the composites in the X-band frequency range decreased for the carbon mesostructures in the following order: CMK-3-filled > CMK-1-filled > CS41-filled. Our study provides technical directions for designing and preparing high-performance EMI shielding materials. Our OMC-based silica composites can be used for EMI shielding, especially in high-temperature or corrosive environments, owing to the high stability of the OMC/OMS fillers and the SiO2 matrix. Related shielding mechanisms are also discussed.

Voltage Oscillations in Single‐Chamber Fuel Cells Operating under a C3H8/O2 Mixture

AbstractSingle‐chamber fuel cells (SCFCs) are an alternative way to conventional SOFCs. Effectively, they do not require any more sealing between anodic and cathodic compartment's as the cell is fed with a mixture of hydrocarbon and oxygen. This paper deals with voltage oscillations observed with an SCFC composed of GDC (Ce0.9Gd0.1O1.95) supported electrolyte, Ni‐GDC anode and a BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3–δ) cathode, operating in the temperature range 500–600 °C and under various propane and oxygen mixtures, with a C3H8/O2 ratio between 0.2 and 0.66. Electrical and Thermo‐Programmed Oxidation (TPO) measurements combined with SEM observations allowed us proving that these oscillations are due to carbon nanowires deposition/oxidation cycles. A mechanism is proposed to explain this behavior.

Pure carbon-based Schottky diode, an implication of stretched carbon nanowire

Density functional theory calculations are performed on various forms of linear carbon chains. It has been predicted that stretched carbon nanowire may be stabilized through interchain interaction thereby forming a quasi-bound state of carbon, naming parallel carbon nanowire (PCNW). The electronic structure analysis on PCNW indicates that this ladder type of structure is achieved through lateral overlap between unhybridised p orbitals of sp C atoms. Furthermore, electronic transport calculations using nonequilibrium Green's function reveal that this material can be properly utilized as Schottky barrier diode with appreciable voltage rectifying capability when connected to asymmetrical metallic contacts, which may have potential application as field effect transistor.

Catalytic growth of carbon nanowires on composite diamond/silicon substrates

Polycrystalline diamond (PCD) films and carbon nanowires (CNWs) provide individually highly attractive properties for science and technology applications. The possibility of carbon composite materials made from a combination of these materials remains a potential approach widely discussed in literature but modestly investigated. We report in this work an early attempt to explore this opportunity in the light of some specific experimental considerations. Carbon nanowires (CNWs) are grown at low temperature without the conventional use of external hydrocarbon vapor source on silicon substrates partially covered by a thin film of coalesced micrometric CVD diamond. Composite substrates constituted by PCD on silicon were first cleaned with H2 plasma then used for the PVD deposition of 5nm Ni thin films. Then, samples were heat treated in a CVD reactor at 580°C in the presence of pure H2 pressure of 60hPa at different annealing times. Comparative effect of annealing time on the dewetting of Ni thin films and the subsequent CNWs growth process was considered in this work using systematic observations by SEM. Possible mechanisms underlying CNWs growth in pure H2 gas were proposed. The nature and structure of these CNWs have been investigated by TEM microscopy and by Raman spectroscopy on the sample showing the highest CNWs density.

Dynamic 3D modeling and simulation of nanoparticles manipulation using an AFM nanorobot

SUMMARYDue to the growing use of Atomic Force Microscope (AFM) nanorobots in the moving and manipulation of cylindrical nanoparticles (carbon nanotubes and nanowires) and the fact that these processes cannot be simultaneously observed, a computer simulation of the involved forces for the purpose of predicting the outcome of the process becomes highly important. So far, no dynamic 3D model that shows changes in these forces in the course of process implementation has been presented. An algorithm is used in this paper to show in 3D, the manner by which the dynamic forces vary in the mentioned process. The presented model can simulate the forces exerted on the probe tip during the manipulation process in three directions. Because of the nonlinearity of the presented dynamic model, the effective parameters have been also studied. To evaluate the results, the parameters of the 3D case (cylindrical model) are gradually reduced and it is transformed into a 2D model (disk model); and we can observe a good agreement between the results of the two simulations. Next, the simulation results are compared with the experimental results, indicating changes in lateral force. With the help of the offered dynamic model, the cantilever deformation and the forces interacting between probe tip and particle can be determined from the moment the probe tip contacts the nanoparticle to when the nanoparticle dislodges from the substrate surface.

Highly Disordered Carbon as a Superior Anode Material for Room‐Temperature Sodium‐Ion Batteries

Highly Disordered Carbon as a Superior Anode Material for Room‐Temperature Sodium‐Ion Batteries

Microscopic and Spectroscopic Analyses of Pt-Decorated Carbon Nanowires Formed on Carbon Fiber Paper

We report the synthesis of carbon nanowires (CNWs) via chemical vapor deposition using catalytic decomposition of ethanol on nanosized transition metals such as Co, Fe, and Ni. Dip-coating process was used for the formation of catalytic nanoparticles, inducing the growth of CNWs on the surface of the carbon fiber paper (CFP). The liquid ethanol used as carbon source was atomized by an ultrasonic atomizer and subsequently flowed into the reactor that was heated up to a synthesis temperature of 600-700°C. Microscopic images show that CNWs of <50 nm were densely synthesized on the surface of the CFP. Raman spectra reveal that a higher synthesis temperature leads to the growth of higher crystalline CNWs. In addition, we demonstrate the successful decoration of platinum nanoparticles on the surface of the prepared CNWs/CFP using the electrochemical deposition technique.

Pore size distribution of ordered nanostructured carbon CMK-3 by means of experimental techniques and Monte Carlo simulations

The design and study of new materials with specific properties is interesting in several scientific and technological fields. In the last years, nanostructured carbons (NC) have rapidly attracted the attention of some researchers due to their physicochemical properties useful for many applications among them in adsorption and catalysis.In this work, the synthesis of a NC was carried out by a nanocasting method, using as a template a very ordered mesoporous material (SBA-15) and sucrose as carbon source. The final material consists of an ordered arrangement of parallel carbon nanorods bonded with some carbon nanowires (CMK-3 type), formed in the mesopores and micropores of the inorganic matrix. The inorganic matrix and the NC were structurally characterized by X-ray diffraction, texturally by N2 sorption at 77K, and morphologically by scanning electron microscopy. The Nitrogen experimental isotherms were simulated using Grand Canonical Monte Carlo (GCMC) method based on two kernels using slit and cylindrical pore models. From these models were obtained the pore size distributions (PSD) which were compared with those obtained by Quenched Solid Density Functional Theory (QSDFT) model. The GCMC simulation showed a good agreement with experimental adsorption isotherms and some differences with the corresponding pore size distribution obtained by Density Functional Theories Methods. These correlations validate the presented GCMC method as an alternative to study in detail the porosity of these materials.

Ingestion of gallium phosphide nanowires has no adverse effect on Drosophila tissue function

Engineered nanoparticles have been under increasing scrutiny in recent years. High aspect ratio nanoparticles such as carbon nanotubes and nanowires have raised safety concerns due to their geometrical similarity to asbestos fibers. III–V epitaxial semiconductor nanowires are expected to be utilized in devices such as LEDs and solar cells and will thus be available to the public. In addition, clean-room staff fabricating and characterizing the nanowires are at risk of exposure, emphasizing the importance of investigating their possible toxicity. Here we investigated the effects of gallium phosphide nanowires on the fruit fly Drosophila melanogaster. Drosophila larvae and/or adults were exposed to gallium phosphide nanowires by ingestion with food. The toxicity and tissue interaction of the nanowires was evaluated by investigating tissue distribution, activation of immune response, genome-wide gene expression, life span, fecundity and somatic mutation rates. Our results show that gallium phosphide nanowires applied through the diet are not taken up into Drosophila tissues, do not elicit a measurable immune response or changes in genome-wide gene expression and do not significantly affect life span or somatic mutation rate.

Synthesis Of Carbon Nanowires By SHI Irradiation Of Fullerene C70 thin Film

Electrically conducting carbon nanowires, all parallel to each other and embedded in fullerene C70 matrix are created by swift heavy ion irradiation of thin fullerene C70 film at low fluences (up to 10 10 ions/cm 2 ). The conductivity of the wires is several orders of magnitude higher than the surrounding material and it is due to the transformation of fullerene into amorphous carbon within each ion hit zone. These conducting nanowires are evidenced by conducting atomic force microscopy. The typical diameter of the conducting tracks is observed to be about 11-21 nm.

H+, N+, and Ar+ ion irradiation induced structure changes of carbon nanostructures

The effects of H + , N + , and Ar + ion irradiation on structural changes in multi-walled carbon nanotubes (MWCNTs) and amorphous carbon nanowires (a-CNWs) were investigated at room and elevated temperatures with different irradiation doses. It is found that at room temperature, defects were introduced in MWCNTs under 70 keV N + ion beam irradiation at a low dose of 1 × 10 16 ions/cm 2 while MWCNTs transformed into a-CNWs at a high dose of 7 × 10 16 ions/cm 2 . At 1000 K, the 70 keV N + ion beam irradiation of defective MWCNTs causes the curling of carbon clusters to an onion-like structure at a dose of 4 × 10 16 ions/cm 2 and the formation of a low density onion-like structure at 7 × 10 16 ions/cm 2 . Irradiation of the defective MWCNTs by 70 keV Ar + ion at 1000 K and 7 × 10 16 ions/cm 2 leads to the formation of a high density onion-like structure. Irradiation of a-CNWs with 70 keV H + ion at 1000 K gradually increases the fraction of material with a diamond structure with increasing dose from 1 × 10 16 to 1 × 10 17 ions/cm[2]. [New Carbon Materials 2013, 28(2): 81–87]

Clinical Applications of Biosensors Based on Field-Effect Transistors with Carbon Nanotubes or Nanowires

Clinical Applications of Biosensors Based on Field-Effect Transistors with Carbon Nanotubes or Nanowires

H+, N+, and Ar+ ion irradiation induced structure changes of carbon nanostructures

The effects of H+, N+, and Ar+ ion irradiation on structural changes in multi-walled carbon nanotubes (MWCNTs) and amorphous carbon nanowires (a-CNWs) were investigated at room and elevated temperatures with different irradiation doses. It is found that at room temperature, defects were introduced in MWCNTs under 70 keV N+ ion beam irradiation at a low dose of 1×1016 ions/cm2 while MWCNTs transformed into a-CNWs at a high dose of 7×1016 ions/cm2. At 1 000 K, the 70 keV N+ ion beam irradiation of defective MWCNTs causes the curling of carbon clusters to an onion-like structure at a dose of 4×1016 ions/cm2 and the formation of a low density onion-like structure at 7×1016 ions/cm2. Irradiation of the defective MWCNTs by 70 keV Ar+ ion at 1 000 K and 7×1016 ions/cm2 leads to the formation of a high density onion-like structure. Irradiation of a-CNWs with 70 keV H+ ion at 1 000 K gradually increases the fraction of material with a diamond structure with increasing dose from 1×1016 to 1×1017 ions/cm2.