Coaxial Nanocables Research Articles

Single crystalline wurtzite ZnO/zinc blende ZnS coaxial heterojunctions and hollow zinc blende ZnS nanotubes: synthesis, structural characterization and optical properties.

Synthesis of ZnO/ZnS heterostructures under thermodynamic conditions generally results in the wurtzite (WZ) structure of the ZnS component because its WZ phase is thermodynamically more stable than its zinc blende (ZB) phase. In this report, we demonstrate for the first time the preparation of ZnO/ZnS coaxial nanocables composed of single crystalline ZB structured ZnS epitaxially grown on WZ ZnO via a two-step thermal evaporation method. The deposition temperature is believed to play a crucial role in determining the crystalline phase of ZnS. Through a systematic structural analysis, the ZnO core and the ZnS shell are found to have an orientation relationship of (0002)ZnO(WZ)//(002)ZnS(ZB) and [01-10]ZnO(WZ)//[2-20]ZnS(ZB). Observation of the coaxial nanocables in cross-section reveals the formation of voids between the ZnO core and the ZnS shell during the coating process, which is probably associated with the nanoscale Kirkendall effect known to result in porosity. Furthermore, by immersing the ZnO/ZnS nanocable heterojunctions in an acetic acid solution to etch away the inner ZnO cores, single crystalline ZnS nanotubes orientated along the [001] direction of the ZB structure were also achieved for the first time. Finally, optical properties of the hollow ZnS tubes were investigated and discussed in detail. We believe that our study could provide some insights into the controlled fabrication of one dimensional (1D) semiconductors with desired morphology, structure and composition at the nanoscale, and the synthesized WZ ZnO/ZB ZnS nanocables as well as ZB ZnS nanotubes could be ideal candidates for the study of optoelectronics based on II-VI semiconductors.

Strongly coupled carbon nanofiber–metal oxide coaxial nanocables with enhanced lithium storage properties

A facile two-step strategy involving a polyol method and subsequent thermal annealing treatment is successfully developed for the general synthesis of metal oxide/carbon coaxial nanocables. Benefitting from the strong coupling effect, these hybrid nanocables exhibit remarkable lithium storage properties with high capacity, long cycle life and excellent rate capability.

Fabrication of one-dimensional heterostructured TiO2@SnO2with enhanced photocatalytic activity

TiO2@SnO2 nanosheets@nanotubes heterostructures were successfully prepared by a facile two-step method: prefabricated SnO2@PNT coaxial nanocables based on the in situ growth of SnO2 in the sulfonated gel matrix of polymeric nanotubes, and then the assembly of TiO2 nanoclusters that consist of ultrathin nanosheets through a solvothermal process. These heterostructures were characterized for the morphological, structural and optical properties by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) and diffuse reflectance spectroscopy (DRS). The photocatalytic investigations showed that the TiO2@SnO2 heterostructures possessed enhanced photocatalytic efficiency in the photodegradation of Rhodamine B (RhB) and photocatalytic H2 evolution from water splitting under ultraviolet (UV) light irradiation, compared with the pristine TiO2 nanosheets, SnO2 nanotubes, the mechanically mixed two samples and P25. The enhanced photocatalytic performance can be ascribed to the beneficial microstructure and synergistic effects of coupled TiO2@SnO2 nanosheets@nanotubes heterostructures.

Ammonia sensing properties of (SnO2–ZnO)/polypyrrole coaxial nanocables

In this work, (SnO2–ZnO)/polypyrrole (PPy) coaxial nanocables have been synthesized through simple chemical routes. The SnO2–ZnO composite nanofibers with narrow distribution of diameter size and an average of 75 nm were synthesized via the electrospinning method. In this experiment, we were able to polymerize a shell of PPy, as a typical conducting polymer, on surface of SnO2–ZnO nanofibers using the vapor-phase polymerization of Pyrrole monomer. The prepared nanomaterial exhibits a linear response to Ammonia (NH3) concentrations at room temperature. The obtained results make NH3 detection and determination of its concentration feasible. The superior features of this nanomaterial include simple synthesis method, high sensitivity, and quick response and recovery times. The aforementioned characteristics of this nanomaterial indicate the potential of industrial applications.

Fabrication of a Silica Nanocable Using Hydroxyl-Group Core-Engineered Filamentous Virus

Biological materials with surface-active proteins can be genetically modified to bind target materials. In particular, filamentous-shaped M13 bacteriophages (M13 phage) are attractive scaffolds for functional nanostructures due to their highly ordered protein-coat surface. This paper demonstrates a simple method for fabricating silica nanocables along a modified M13 phage. The M13 phage was genetically engineered to display the amino acid serine on the surface to provide hydroxyl groups for a sol-gel reaction. This M13 phage mutant offers homogeneous molecular templates for forming silica coated coaxial nanocables. Silica shell formation was confirmed by transmission electron microscopy (TEM) and electron dispersive X-ray (EDX) analysis. The core-shell structures were clearly distinguishable in the TEM analysis, and the synthesized shells were observed by EDX analysis. In addition, we investigated the adsorption properties of M13 phages on the pretreated substrate as a function of concentration. The effect of the relative concentration of M13 phages on the substrate was observed by using atomic force microscopy (AFM). We also fabricated top electrodes on the extremely dense network for measuring electrical properties of the M13 phage. The experimental DC measurement indicated that the wild-type phage has very low electrical conductance, similar to insulating material.

CNT@Fe3O4@C Coaxial Nanocables: One‐Pot, Additive‐Free Synthesis and Remarkable Lithium Storage Behavior

By using carbon nanotubes (CNTs) as a shape template and glucose as a carbon precursor and structure-directing agent, CNT@Fe3O4@C porous core/sheath coaxial nanocables have been synthesized by a simple one-pot hydrothermal process. Neither a surfactant/ligand nor a CNT pretreatment is needed in the synthetic process. A possible growth mechanism governing the formation of this nanostructure is discussed. When used as an anode material of lithium-ion batteries, the CNT@Fe3O4@C nanocables show significantly enhanced cycling performance, high rate capability, and high Coulombic efficiency compared with pure Fe2O3 particles and Fe3O4/CNT composites. The CNT@Fe3O4@C nanocables deliver a reversible capacity of 1290 mA h g(-1) after 80 cycles at a current density of 200 mA g(-1), and maintain a reversible capacity of 690 mA h g(-1) after 200 cycles at a current density of 2000 mA g(-1). The improved lithium storage behavior can be attributed to the synergistic effect of the high electronic conductivity support and the inner CNT/outer carbon buffering matrix.

Heteroepitaxial Growth of GaP/ZnS Nanocable with Superior Optoelectronic Response

We demonstrate the controlled growth of coaxial nanocables composed of GaP/ZnS core-shell structures by a facile chemical vapor deposition method. Structural analysis confirms that the cubic GaP (111) plane and wurtzite ZnS (0001) plane present close similarities in terms of hexagonal-arranged atomic configuration with small in-plane lattice mismatch, and the ZnS shell is epitaxially grown on the (100) plane of the cubic GaP core. Compared with the unitary ZnS nanobelts, the GaP/ZnS coaxial nanocables exhibit improved optoelectronic properties such as high photocurrent and excellent photocurrent stability. This approach opens up new strategy to boost the performance of ZnS-based photodetectors.

Fabrication and Characterization of Ag@C Nanocables with High Aspect Ratios by Hydrothermal Process

Abstract. This paper describes that high-yield Ag/C coaxial nanocables has been obtained via a simple hydrothermal approach through the in situ reaction of Ag+ and glucose in the condition of CTAB. The glucose not only acts as reducing agent but also as carbon source. It was found that high aspect ratio(>400)of nanocables with Ag nanowires core diameter (20-60)nm and various carbon shell thickness had been prepared in large scale with a facile aqueous reduction route at low temperatures for different times. All of the products were characterized in detail by multiform techniques: X-ray diffraction(XRD), transmission electron microscopy(TEM), high-resolution TEM(HRTEM), scanning electron microscopy(SEM), energy-dispersive X-ray spectroscopy (EDX).

Hierarchical nanostructured composite cathode with carbon nanotubes as conductive scaffold for lithium-sulfur batteries

Carbon nanotubes (CNTs) are excellent scaffolds for advanced electrode materials, resulting from their intrinsic sp2 carbon hybridization, interconnected electron pathway, large aspect ratio, hierarchical porous structures, and low cost at a large-scale production. How to make full utilization of the mass produced CNTs as building blocks for nanocomposite electrodes is not well understood yet. Herein, a composite cathode containing commercial agglomerated multi-walled CNTs and S for Li-S battery was fabricated by a facile melt-diffusion strategy. The hierarchical CNT@S coaxial nanocables exhibited a discharging capacity of 1020 and 740 mAh ·g–1 at 0.5 and 2.0 C, respectively. A rapid capacity decay of 0.7% per cycle at the initial 10 cycles and a slow decay rate of 0.14% per cycle for the later 140 cycles were detected. Such hierarchical agglomerated CNT@S cathodes show advantages in easy fabrication, environmentally benign, low cost, excellent scalability, and good Li ion storage performance, which are extraordinary composites for high performance Li-S battery.

Electrospinning fabrication of high-performance magnetic@photoluminescent bifunctional coaxial nanocables

Novel magnetic@photoluminescent bifunctional coaxial nanocables have been successfully fabricated by electrospinning technology. As an example, Terbium complex Tb(BA)3phen (BA=benzoic acid, phen=1,10-phenanthroline) and ferroferric oxide nanoparticles were incorporated into polyvinyl pyrrolidone (PVP) and electrospun into coaxial nanocables with Fe3O4/PVP as core and Tb(BA)3phen/PVP as the shell. The morphology and properties of the final products were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and a fluorescence spectrometer. The core diameter was ca. 150nm containing magnetic nanoparticles and the shell thickness was ca. 110nm. Fluorescence emission peaks of Tb3+ in the Fe3O4/PVP@Tb(BA)3phen/PVP coaxial nanocables were observed. Compared with Tb(BA)3phen/PVP nanofibers, the luminescent intensity of the Fe3O4/PVP@Tb(BA)3phen/PVP coaxial nanocables was almost not weakened in spite of the existence of the non-luminescent Fe3O4/PVP core. The as-prepared coaxial nanocables possessed excellent magnetic properties. The new type bifunctional magnetic–photoluminescent Fe3O4/PVP@Tb(BA)3phen/PVP coaxial nanocables have many potential applications in display device, nanorobots, protein determination and target delivery of drug due to their excellent magnetism and fluorescence.

Synthesis of coaxial nanocables of single-walled carbon nanotubes sheathed with amorphous silicon oxide

Synthesis of coaxial nanocables of single-walled carbon nanotubes sheathed with amorphous silicon oxide

Facile fabrication of multiwalled carbon nanotube/α-MnOOH coaxial nanocable films by electrophoretic deposition for supercapacitors

Multiwalled carbon nanotube (MWCNT)/α-MnOOH coaxial nanocable (MMCNC) films are successfully fabricated by a simple and low-cost electrophoretic deposition (EPD) process. The as-prepared MMCNC films exhibit three-dimensional (3D) nanoporous network structure. A possible mechanism is proposed to explain the formation of the MMCNC films. Electrochemical test results show that the films exhibit superior capacitive behaviors and cycle stability in 0.1 M Na2SO4 aqueous solution. The thickness, mass loading and capacitive performance of the MMCNC films can be easily and continuously tuned by varying the deposition time. A relatively high mass specific capacitance of 327 F g−1 is obtained from the films with relatively low mass loading of 0.05 mg cm−2, while, a relatively high areal capacitance of 0.2 F cm−2 is achieved when the mass loading was increased to 1.38 mg cm−2. The superior capacitive performances can be attributed to the unique structure advantages of the MMCNC films. On one hand, the one-dimensional (1D) coaxial nanocable structure works, with MWCNT core serving as high electronic conductive frame and α-MnOOH sheath providing high pseudocapacitance. On the other hand, the 3D nanoporous network structure can facilitate fast ions transportation.

Composite Cathodes Containing SWCNT@S Coaxial Nanocables: Facile Synthesis, Surface Modification, and Enhanced Performance for Li‐Ion Storage

The arrangement and construction of 1D carbon nanotubes (CNTs) into frameworks with two or more levels of structures is an essential step to demonstrate their intrinsic properties and promising applications for energy storage. Single‐walled CNTs (SWCNTs) are considered to have more excellent properties compared with multiwalled CNTs (MWCNTs), however, how to appropriately use SWCNTs as building blocks for nanocomposite electrodes is not well understood. Here, a composite cathode containing SWCNT@S coaxial nanocables for Li‐S battery is fabricated by a facile melt‐diffusion strategy. Beneficial from its sp2 carbon nanostructure, higher specific surface area, larger aspect ratio, and interconnected electron pathway, the SWCNT@S cathode have reversible capacities of 676, 441 and 311 mAh g−1 for the first discharging at 0.5 C, 100th discharging at 1.0 C, and discharging at 10.0 C, respectively. These capacities are much higher than the corresponding capacities of the MWCNT@S cathode. By introducing polyethylene glycol (PEG) as a physical barrier to trap the highly polar polysulfide species, the PEG modified SWCNT@S cathode afforded improved reversible capacities. The cycling stability of the reversible capacities is expected to be further improved. The SWCNTs can serve as scaffolds for Li‐S battery with much improved energy storage performance.

Synthesis of coaxial nanocables of single-walled carbon nanotubes sheathed with amorphous silicon oxide

Coaxial nanocables of single-walled carbon nanotubes (SWCNTs) sheathed with amorphous silicon oxide were directly synthesized by a hydrogen arc discharge method. As-prepared nanocables are usually tens of microns in length and about 10–30 nm in diameter. The sheath of the nanocables is amorphous silicon oxide, while the core is high quality SWCNTs. Each cylinder-shaped nanocable contained one to several SWCNTs. The growth mechanism of the nanocables is proposed. These SWCNT/amorphous silicon oxide nanocables may have potential applications in field effect transistors and other related nanodevices.

Synthesis and characterization of coaxial silver/silica/polypyrrole nanocables

AbstractDouble‐shelled coaxial nanocables of silver nanocables with SiO2 and polypyrrole (PPy; Ag/SiO2/PPy) were synthesized by a simple method. The thickness of the outer PPy shell could be controlled by the amount of pyrrole monomer. The silver nanocables encapsulated in the interior of the hollow PPy nanotubes were obtained by the removal of the midlayer SiO2. By the silver‐mirror reaction, flowerlike Ag nanostructures could be formed on the surface of the Ag/SiO2/PPy multilayer nanocable. The application of the as‐prepared Ag/SiO2/PPy–Ag composites in surface‐enhanced Raman scattering (SERS) was studied with Rhodamine B (Rh B) as a probe molecule. We found that the composites could be used as SERS substrates and that they exhibited excellent enhancement ability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Reactive template strategy for fabrication of MnO2/polyaniline coaxial nanocables and their catalytic application in the oxidative decolorization of rhodamine B

MnO2/polyaniline (PANI) coaxial nanocables were fabricated through an oxidative template route, where MnO2 nanorods were selected as the reactive templates for polymerization of aniline in acidic aqueous solution. It was found that PANI could be coated on the surfaces of MnO2 nanorods, accompanied by dissolution of the MnO2 cores, leading to the formation of coaxial nanocable structures. Consequently, the compositions and structures of the MnO2/PANI coaxial nanocables could be simply controlled by determining the reaction time. Thermogravimetric analysis, Fourier transform infrared spectrometry, X-ray diffraction, ultraviolet-visible spectrophotometry, and N2 adsorption–desorption techniques were used to characterize the MnO2/PANI coaxial nanocables. Furthermore, the catalytic activities of the MnO2/PANI coaxial nanocables in the oxidative decolorization of Rhodamine B were also investigated.

Synthesis, Structural and Photoelectrical Properties of Self-Assembled Gold-Poly(3,4-Ethylenedioxythiophene) Nanowires and Nanocables

Gold-poly (3,4-ethylenedioxythiophene) (Au-PEDOT) nanowires with Au nanoparticles embedded in the polymer matrix and polyvinylpyrrolidone (PVP) modified Au-PEDOT coaxial nanocables with a core-shell structure have been synthesized by a new and facile self-assembly method. The morphology and structure features of the composites were characterized by transmission electron microscopy, selected-area electron diffraction, and energy-dispersive x-ray spectrometry. The room-temperature electrical conductivity of the casted composite films was about 0.21 S/cm. Photoresponse of the films were also investigated with respect to wide potential applications of the multifunctional composites. Clear photocurrent switching characteristic during switching on/off of a xenon lamp was observed.

Multimodal porous CNT@TiO2 nanocables with superior performance in lithium-ion batteries

Multimodal porous CNT@TiO2 core–sheath coaxial nanocables have been constructed by a sol–gel method and post-calcination in the presence of polymer nanotubes acting as a template and carbon source. The composite exhibits excellent electrochemical properties, attaining a high discharge capacity of 231 mA h g−1 at 1000 mA g−1 for up to 110 cycles.

Structural and electronic properties of coaxial nanocables of AlN nanowire core and SiC nanotube sheath: A first-principles study

Under the generalized gradient approximation (GGA), the structural and electronic properties of coaxial nanocables of AlN nanowire core and SiC nanotube sheath have been investigated by using the first-principles projector-augmented wave (PAW) potential within the density function theory (DFT) framework. The combining processes of all three hybrid systems are exothermic and the most stable structure is AlNNW@(9,0) SiCNT system. The C1Al1 and N1Si1 ionic binding characters between the SiCNT and the AlNNW are disclosed. The AlNNW@(9,0) SiCNT system is extremely suitable for application in high-power, high-temperature and high-frequency electronics devices due to its broad energy gap.

Fully Reversible Conversion between SnO2 and Sn in SWNTs@SnO2@PPy Coaxial Nanocable As High Performance Anode Material for Lithium Ion Batteries

In this report, we designed a novel SWNTs@SnO2@PPy coaxial nanocable as superior anode material for the first time. The nanosized SnO2 particles (2–3 nm) were uniformly distributed between one dimension SWNTs core and PPy shell, as confirmed by XRD, SEM, and TEM characterizations. As an anode material for lithium ion batteries, this composite delivered a high capacity of 823 mAh g–1 at 150 mA g–1 after 100 cycles. Even at a high rate of 3000 mA g–1, a reversible capacity of 480 mAh g–1 still remained. Furthermore, the SnO2 in this composite exhibited a large capacity of 1486 mAh g–1 as well as good capacity retention of 95% over 100 cycles. This result indicated the completely reversible reaction between Li4.4Sn and SnO2, greatly improving the theoretical capacity of SnO2 from 782 to 1493 mAh g–1.