A simple route to synthesize carbon-nanotube/cadmium-sulfide hybrid heterostructures and their optical properties

Multi-walled carbon nanotube/cadmium sulfide hybrid heterostructures were easily synthesized by employing a thermal decomposition of thioacetamide as a sulfide-ion source in an aqueous regime. The resulting cadmium-sulfide phase is comprised of a zinc-blende structure of spherical polycrystalline nanoparticles (cadmium-sulfide nanoclusters) with the subunits of ca. 15 nm, deposited on the nanotube surface. The formation of the cadmium-sulfide nanoparticles with zinc-blende structure (cubic crystal) suggests that the local concentrations of reacting ion species in the vicinity of the nanotube surface are different from those in the reaction solution. The cadmium-sulfide nanoparticles are comprised of a stoichiometrically ideal chemical-composition ratio (cadmium: sulfur=1:1.02) of cadmium and sulfur with the valence states of +2 and −2, respectively. The optical responses of the cadmium-sulfide phase for ultraviolet-visible light and photoluminescence spectroscopes show the proper size-effect and inherent optical properties of the cadmium-sulfide nanoparticles.     

A simple large-scale synthesis of very long aligned silica nanowires

A simple method based on the thermal oxidation of Si wafers has been discovered to provide a large-scale synthesis of very long, aligned silica nanowires. The as-grown product was characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and photoluminescence. The obtained SiO₂ nanowires had no metal contaminations, ultralong lengths of millimeters, and most diameters of ∼50 nm. The PL spectra of the SiO₂ nanowires showed a strong and stable green emission at 540 nm. The nucleation and growth of the SiO₂ nanowires were investigated.     

A simple solution route to single-crystalline Sb2O3 nanowires with rectangular cross sections

We report a simple solution route to large-scale synthesis of uniform, single-crystalline, and well-faceted orthorhombic antimony trioxide (Sb(2)O(3)) nanowires with rectangular cross sections by direct air oxidation of bulk metal antimony (Sb) in a mixed solution made of ethylenediamine (EDA) and deionized water (DIW). The as-synthesized products were analyzed by range of methods, such as XRD, SEM, EDX, TEM, SAED, HRTEM, FTIR, Raman, UV-vis absorption, and photoluminescence (PL) spectra. The as-synthesized Sb(2)O(3) nanowires with rectangular cross sections are usually hundreds of micrometers in length, typically 80-100 nm in width, and 60-80 nm in thickness. The novel room temperature photoluminescence properties of Sb(2)O(3) nanowires with rectangular cross sections displayed a significant UV luminescence with a strong emission band at 374 nm, which was reported for the first time, indicating the as-synthesized products with an optical band gap E(g) = 3.3 eV. It is expected that as-synthesized Sb(2)O(3) nanowires would be a new member of functional materials and used in the manufacture of advanced nanodevices.     

A surfactant-free route to single-crystalline CeO2 nanowires

A surfactant-free route was successfully established to synthesize CeO2 single-crystalline nanowires using H2O2 as oxidizer and template agent.     

A simple method to synthesize single-crystalline lanthanide orthovanadate nanorods

Single-crystalline tetragonal LnVO₄ (Ln=La, Nd, Sm, Eu, Dy) nanorods were prepared via a simple hydrothermal method, in the absence of any surfactant or template using cheap and simple inorganic salts as raw materials. The products were characterized by XRD, TEM, HRTEM, and PL. It has been shown that after the hydrothermal process, LaVO₄ transformed its crystal structure from monoclinic to tetragonal phase, but LnVO₄ (Ln=Nd, Sm, Eu, Dy) have not exhibited the structural change. This could be associated with the change of lanthanide ion radius. TEM and HRTEM results show that the nanorods are pure, structurally uniform, single crystalline, and most of them are free from dislocations. Further study reveals the nanorods grow along the [001] direction. A possible growth mechanism of lanthanide orthovanadate nanorods was also proposed. The advantages of our method for the nanorods synthesis lie in the high yield and the low temperature and mild reaction conditions, which permit large scale production at low cost.     

A simple route to porous ZnO and ZnCdO nanowires

Porous ZnO nanowires were obtained in an inexpensive and simple way by thermally oxidizing ZnSe nanowires in air. The morphologies of the precursor and resulted nanowires are almost identical. X-ray diffraction and energy-dispersive X-ray spectroscopy reveal that the zinc blende ZnSe nanowires were transformed into wurtzite ZnO nanowires after oxidation. Transmission electron microscope measurements indicate that the ZnO nanowires are polycrystalline and are composed of nanoparticles and nanopores. ZnCdO nanowires, which were seldom reported previously, have also been prepared in this way. Just like the ZnO nanowires, the ZnCdO nanowires also show the porous structure. Photoluminescence studies on both ZnO and ZnCdO nanowires show intense near-band edge emissions at room temperature. The transition from one kind of nanowires to another by simple thermal oxidization described in this paper may be applicable to some other compound semiconductors and may open a practical route to yield nanowires.     

A general route to very small polymer particles with controlled microstructures

Very small polymer particles of 10-30 nm size with various microstructures (polyethylene, syndiotactic 1,2-polybutadiene, poly(cycloolefins)) are prepared by catalytic polymerization with aqueous catalyst microemulsion.     

A simple hydrothermal route to large-scale synthesis of uniform silver nanowires

This paper describes the preparation of uniform silver nanowires by reducing freshly prepared silver chloride with glucose at 180 degrees C for 18 hours in the absence of any surfactants or polymers. Scanning electron microscopy studies indicated that the silver nanowires are about 100 nm in diameter and up to 500 microm in length. High-resolution transmission electron microscopy analyses showed that the silver nanowires grow perpendicularly to the Ag(200) plane. The silver nanowires are believed to grow through a solid-solution-solid process. Some influential factors on the growth of silver nanowires are also discussed.     

A template-free aqueous route to ZnO nanorod arrays with high optical property

A mild template-free aqueous route was successfully established to synthesize well-aligned ZnO nanorod arrays, which were proved to exhibit high optical property by PL spectra.     

Preparation of single-crystalline platinum nanowires with small diameters under mild conditions

We report a convenient method to synthesize single-crystalline platinum nanowires with high aspect ratio of ca. 2.0 nm diameter by sophisticated and precise control of Pt(0) nuclei and their growth.     

Facile route to synthesize multiwalled carbon nanotube/zinc sulfide heterostructures: optical and electrical properties

A simple method to decorate the multiwalled carbon nanotubes (MWCNTs) with ZnS nanospheres has been developed. The method involves ultrasonic pretreatment and heat treatments of MWCNTs, zinc chloride, and thiourea in ethanol. The heterostructures have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Comparative experiments show that both ultrasonic treatment and heat treatment are necessary for synthesizing the MWCNTs/ZnS heterostructures. Moreover, a photoluminescence spectrum shows that the MWCNTs/ZnS heterostructures feature a broad blue emission at about 430 nm, indicating that there exists significant ground-state interaction between ZnS nanospheres and MWCNTs. Meanwhile, the current-voltage characteristic of the MWCNTs/ZnS exhibits clear rectifying behavior, revealing charge transfer between MWCNTs and ZnS nanospheres.     

A precursor route to single-crystalline WO3 nanoplates with an uneven surface and enhanced sensing properties

A W-containing inorganic-organic nanohybrid with a plate-like morphology has been successfully prepared through a nonaqueous synthetic route using WCl(6) as the tungsten source and benzyl alcohol as the solvent. The as-prepared hybrid nanomaterial was used directly as an efficient precursor for the formation of WO(3) nanoplates via a simple thermal treatment process. The as-obtained WO(3) material maintains the plate-like morphology of the precursor and possesses a unique uneven surface structure. It is noted that the use of a inorganic-organic hybrid precursor is essential for the creation of an uneven surface on the WO(3) nanoplates, which exhibit high sensitivity and selectivity for the detection of acetone vapour at a relatively low operating temperature (200 °C). The excellent sensing performance of the WO(3) nanomaterial is attributed to its unique uneven surface structure besides the small particle size and ultrathin morphology.     

Growing ordered arrays of vertically aligned copolymer nanowires for supercapacitors with high stability

Journal of Solid State Electrochemistry - In this report, we present a novel platform to study the formation of delicate ordered vertically aligned copolymer nanowires array with EDOT and Py as the...     

Optical and field emission properties of thin single-crystalline GaN nanowires

Thin high-quality gallium nitride (GaN) nanowires were synthesized by a catalytic chemical vapor deposition method. The synthesized GaN nanowires with hexagonal single-crystalline structure had thin diameters of 10-50 nm and lengths of tens of micrometers. The thin GaN nanowires revealed UV bands at 3.481 and 3.285 eV in low-temperature PL measurements due to the recombination of donor-bound excitons and donor-acceptor pairs, respectively. The blue shifts of UV bands in the low-temperature PL measurement were observed, indicating quantum confinement effects in the thin GaN nanowires which have smaller diameters than the exciton Bohr radius, 11 nm. For field emission properties of GaN nanowires, the turn-on field of GaN nanowires was 8.5 V/microm and the current density was about 0.2 mA/cm(2) at 17.5 V/microm, which is sufficient for the applications of field emission displays and vacuum microelectronic devices. Moreover, the GaN nanowires indicated stronger emission stability compared with carbon nanotubes.     

Hydrothermal synthesis and magnetic properties of single-crystalline BiFeO3 nanowires

One-dimensional, single-crystalline BiFeO(3) nanowires presenting a diameter of 45-200 nm and a length from hundreds of nanometres to several microns have been prepared using an improved hydrothermal method. The characterization results of ZFC and FC magnetizations at different temperatures indicate that single-crystalline BiFeO(3) nanowires show a spin-glass transition below the freezing temperature of 55 K.     

Facile solution route to vertically aligned, selective growth of ZnO nanostructure arrays

For any future cost-effective applications of inorganic nanostructures, in particular, hybrid photovoltaic cells, it is essential that these inorganic nanomaterials be solution processable and selectively printable. This letter reports the selective growth of single-crystal ZnO nanostructures based on the microcontact printing of an inorganic nanocrystal seeding film. The pattern-transfer quality is dependent on the concentration of the inking solution. Variable yet controllable anisotropic growth of ZnO nanowires has been demonstrated on the transferred patterns of ZnO nanocrystal films. The patterning and growth of these highly ordered arrays of ZnO nanostructures employ a simple soft lithography technique and mild reaction conditions at low temperature and in the absence of harmful organic additives.     

Simple solvothermal route to synthesize ZnO nanosheets, nanonails, and well-aligned nanorod arrays

ZnO nanosheets, nanonails, and well-aligned nanorods were fabricated on Zn foils by a solvothermal approach using ethanol as the solvent. A lower synthesis temperature and a shorter time period favor the formation of nanosheets. By optimizing the synthesis temperature and time period, ZnO nanonails with a hexagonal cap and a long stem could be produced. A higher temperature was not favorable to produce uniform and smooth nanorods. Well-aligned ZnO nanorod arrays were produced with diameters within 100-250 nm and lengths up to approximately 6 microm when NaOH was added to the solvent. By optimizing the reaction parameters, the morphology, size, and orientation of the nanoforms could be tailored. The ZnO nanorods exhibit an excitonic strong UV emission and a defect-related broad green emission at room temperature. The defect-related green emission band decreased with the improvement of the degree of alignment of the nanorods.     

A simple route to ordered metal oxide nanoparticle arrays using block copolymer thin films

Oxide nanoparticles arrays are easily synthesized in a 3-steps method including (i) the deposition of poly(styrene)-b-poly(4-vinylpyridine) (PS-b-PVP) thin films, (ii) the selective deposition of inorganic precursors and (iii) the synthesis of oxide nanoparticles and the elimination of the polymer scaffold by thermal annealing. The specific staining of the PVP domains by inorganic precursors is obtained in this study thanks to a simple and fast spin coating process using an alcoholic solution of the precursors. This simple lab-procedure is used to synthesize a wide range of metallic (silicon, titanium, cerium, ruthenium, zinc and manganese) oxides, showing that this method can be extended to the synthesis of all kinds of oxides with all kinds of precursors as long as the precursor is soluble in P4VP solvent. It is shown that this strategy can be extended to the synthesis of oxide nanorods.     

A simple and convenient route to prepare poly(vinylidene fluoride trifluoroethylene) copolymer nanowires and nanotubes

Poly(vinylidene fluoride trifluoroethylene) copolymer nanowires and nanotubes have been prepared for the first time via a high temperature (相似文献