PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (449618)

Clipboard (0)
None

Related Articles

1.  Field Emission and Radial Distribution Function Studies of Fractal-like Amorphous Carbon Nanotips 
Nanoscale Research Letters  2009;4(5):431-436.
The short-range order of individual fractal-like amorphous carbon nanotips was investigated by means of energy-filtered electron diffraction in a transmission electron microscope (TEM). The nanostructures were grown in porous silicon substrates in situ within the TEM by the electron beam-induced deposition method. The structure factorS(k) and the reduced radial distribution functionG(r) were calculated. From these calculations a bond angle of 124° was obtained which suggests a distorted graphitic structure. Field emission was obtained from individual nanostructures using two micromanipulators with sub-nanometer positioning resolution. A theoretical three-stage model that accounts for the geometry of the nanostructures provides a value for the field enhancement factor close to the one obtained experimentally from the Fowler-Nordheim law.
doi:10.1007/s11671-009-9270-5
PMCID: PMC2894329  PMID: 20596340
Carbon nanotips; Graphite-like a-C; EELS; EFED; Field emission
2.  Fabrication and characterization of well-aligned and ultra-sharp silicon nanotip array 
Nanoscale Research Letters  2012;7(1):120.
Well-defined, uniform, and large-area nanoscaled tips are of great interest for scanning probe microscopy and high-efficiency field emission. An ultra-sharp nanotip causes higher electrical field and, hence, improves the emission current. In this paper, a large-area and well-aligned ultra-sharp nanotip arrays by reactive ion etching and oxidation techniques are fabricated. The apex of nanotips can be further sharpened to reach 3-nm radius by subsequent oxidation and etching process. A schematic model to explain the formation of nanotip array is proposed. When increasing the etching time, the photoresist on top of the nanotip is also consumed, and the exposed silicon substrate is etched away to form the nanotip. At the end, the photoresist is consumed completely and a nanotip with pyramid-like shape is developed. The field emission property was measured, and the turn-on field and work function of the ultra-sharp nanotip was about 5.37 V/μm and 4.59 eV, respectively. A nanotip with an oxide layer capped on the sidewall is also fabricated in this paper. Comparing to the uncapped nanotip, the oxide-capped sample exhibits stable and excellent field emission property against environmental disturbance.
doi:10.1186/1556-276X-7-120
PMCID: PMC3292956  PMID: 22330967
silicon nanotip; well-aligned; field emission; Fowler-Nordheim; oxide-capped
3.  Paradox of low field enhancement factor for field emission nanodiodes in relation to quantum screening effects 
Nanoscale Research Letters  2012;7(1):125.
We put forward the quantum screening effect in field emission [FE] nanodiodes, explaining relatively low field enhancement factors due to the increased potential barrier that impedes the electron Fowler-Nordheim tunneling, which is usually observed in nanoscale FE experiments. We illustratively show this effect from the energy band diagram and experimentally verify it by performing the nanomanipulation FE measurement for a single P-silicon nanotip emitter (Φ = 4.94eV), with a scanning tungsten-probe anode (work function, Φ = 4.5eV) that constitutes a 75-nm vacuum nanogap. A macroscopic FE measurement for the arrays of emitters with a 17-μm vacuum microgap was also performed for a fair comparison.
doi:10.1186/1556-276X-7-125
PMCID: PMC3292933  PMID: 22333408
quantum screening effects; field emission; vacuum electronics; Fowler-Nordheim tunneling; silicon nanostructures
4.  Growth of GeSi nanoislands on nanotip-patterned Si (100) substrates with a stress-induced self-limiting interdiffusion 
Nanoscale Research Letters  2012;7(1):346.
GeSi nanoislands grown on nanotip pre-patterned Si substrates at various temperatures are investigated. Nanoislands with a high density and narrow size distribution can be obtained within an intermediate temperature range, and the Ge atom diffusion length is comparable to half of the average distance of the Si nanotips. The Ge concentration distributions at the center and edge of the GeSi nanoislands are measured by scanning transmission electron microscopy. The results reveal that there is a Si core at the center of the GeSi nanoisland, but the Ge concentration presents a layered distribution above the Si nanotips. The radial component of the stress field in Ge layer near the Ge/Si interface on the planar, and the nanotip regions is qualitatively discussed. The difference of the stress field reveals that the experimentally observed concentration profile can be ascribed to the stress-induced interdiffusion self-limiting effect of the Si nanotips.
doi:10.1186/1556-276X-7-346
PMCID: PMC3442980  PMID: 22734613
GeSi nanoislands; Nanotip pre-patterned Si substrates; Ge concentration distribution; Stress-induced interdiffusion self-limiting effect; PACS; 68.35.Gy; 61.46.-w; 66.30.Pa
5.  Thickness dependency of field emission in amorphous and nanostructured carbon thin films 
Nanoscale Research Letters  2012;7(1):286.
Thickness dependency of the field emission of amorphous and nanostructured carbon thin films has been studied. It is found that in amorphous and carbon films with nanometer-sized sp2 clusters, the emission does not depend on the film thickness. This further proves that the emission happens from the surface sp2 sites due to large enhancement of electric field on these sites. However, in the case of carbon films with nanocrystals of preferred orientation, the emission strongly depends on the film thickness. sp2-bonded nanocrystals have higher aspect ratio in thicker films which in turn results in higher field enhancement and hence easier electron emission.
doi:10.1186/1556-276X-7-286
PMCID: PMC3431989  PMID: 22655860
Carbon films; Preferred orientation; Field emission
6.  Electrolyte-free Amperometric Immunosensor using a Dendritic Nanotip† 
RSC advances  2013;3(13):4281-4287.
Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. Sensors composed of nanotips or nanodots have been described for highly sensitive amperometry enabled by confined geometry. However, both fabrication and use of nanostructured sensors remain challenging. This paper describes a dendritic nanotip used as an amperometric biosensor for highly sensitive detection of target bacteria. A dendritic nanotip is structured by Si nanowires coated with single-walled carbon nanotubes (SWCNTs) for generation of a high electric field. For reliable measurement using the dendritic structure, Si nanowires were uniformly fabricated by ultraviolet (UV) lithography and etching. The dendritic structure effectively increased the electric current density near the terminal end of the nanotip according to numerical computation. The electrical characteristics of a dendritic nanotip with additional protein layers was studied by cyclic voltammetry and I–V measurement in deionized (DI) water. When the target bacteria dielectrophoretically captured onto a nanotip were bound with fluorescence antibodies, the electric current through DI water decreased. Measurement results were consistent with fluorescence- and electron microscopy. The sensitivity of the amperometry was 10 cfu/sample volume (103 cfu/mL), which was equivalent to the more laborious fluorescence measurement method. The simple configuration of a dendritic nanotip can potentially offer an electrolyte-free detection platform for sensitive and rapid biosensors.
doi:10.1039/C3RA40262B
PMCID: PMC3622275  PMID: 23585927
7.  Field emission properties and growth mechanism of In2O3 nanostructures 
Nanoscale Research Letters  2014;9(1):111.
Four kinds of nanostructures, nanoneedles, nanohooks, nanorods, and nanotowers of In2O3, have been grown by the vapor transport process with Au catalysts or without any catalysts. The morphology and structure of the prepared nanostructures are determined on the basis of field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). The growth direction of the In2O3 nanoneedles is along the [001], and those of the other three nanostructures are along the [100]. The growth mechanism of the nanoneedles is the vapor-liquid–solid (VLS), and those of the other three nanostructures are the vapor-solid (VS) processes. The field emission properties of four kinds of In2O3 nanostructures have been investigated. Among them, the nanoneedles have the best field emission properties with the lowest turn-on field of 4.9 V/μm and the threshold field of 12 V/μm due to possessing the smallest emitter tip radius and the weakest screening effect.
doi:10.1186/1556-276X-9-111
PMCID: PMC3995944  PMID: 24612921
Thermal evaporation; Field emission; Crystal growth; Growth mechanism
8.  Improved field emission stability from single-walled carbon nanotubes chemically attached to silicon 
Nanoscale Research Letters  2012;7(1):432.
Here, we demonstrate the simple fabrication of a single-walled carbon nanotube (SWCNT) field emission electrode which shows excellent field emission characteristics and remarkable field emission stability without requiring posttreatment. Chemically functionalized SWCNTs were chemically attached to a silicon substrate. The chemical attachment led to vertical alignment of SWCNTs on the surface. Field emission sweeps and Fowler-Nordheim plots showed that the Si-SWCNT electrodes field emit with a low turn-on electric field of 1.5 V μm−1 and high electric field enhancement factor of 3,965. The Si-SWCNT electrodes were shown to maintain a current density of >740 μA cm−2 for 15 h with negligible change in applied voltage. The results indicate that adhesion strength between the SWCNTs and substrate is a much greater factor in field emission stability than previously reported.
doi:10.1186/1556-276X-7-432
PMCID: PMC3492060  PMID: 22853557
Single-walled carbon nanotubes; Chemical attachment; Field emission; Field emission stability; Nanoelectronics
9.  Enhanced photocatalytic activity of Ag–ZnO hybrid plasmonic nanostructures prepared by a facile wet chemical method 
Summary
We report the synthesis of Ag–ZnO hybrid plasmonic nanostructures with enhanced photocatalytic activity by a facile wet-chemical method. The structural, optical, plasmonic and photocatalytic properties of the Ag–ZnO hybrid nanostructures were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV–visible absorption spectroscopy. The effects of citrate concentration and Ag nanoparticle loading on the photocatalytic activity of Ag–ZnO hybrid nanostructures towards sun-light driven degradation of methylene blue (MB) have been investigated. Increase in citrate concentration has been found to result in the formation of nanodisk-like structures, due to citrate-assisted oriented attachment of ZnO nanoparticles. The decoration of ZnO nanostructures with Ag nanoparticles resulted in a significant enhancement of the photocatalytic degradation efficiency, which has been found to increase with the extent of Ag nanoparticle loading.
doi:10.3762/bjnano.5.75
PMCID: PMC4077307  PMID: 24991500
Ag–ZnO; hybrid plasmonic nanostructures; photocatalysis
10.  Magnetically interacting low dimensional Ni-nanostructures within porous silicon 
Microelectronic Engineering  2012;90(C):83-87.
Graphical abstract
Electrodeposition of ferromagnetic metals, a common method to fabricate magnetic nanostructures, is used for the incorporation of Ni structures into the pores of porous silicon templates. The porous silicon is fabricated in various morphologies with average pore-diameters between 40 and 95 nm and concomitant pore-distances between 60 and 40 nm. The metal nanostructures are deposited with different geometries as spheres, ellipsoids or wires influenced by the deposition process parameters. Furthermore small Ni-particles with diameters between 3 and 6 nm can be deposited on the walls of the porous silicon template forming a metal tube. Analysis of this tube-like arrangement by transmission electron microscopy (TEM) shows that the distribution of the Ni-particles is quite narrow, which means that the distance between the particles is smaller than 10 nm. Such a close arrangement of the Ni-particles assures magnetic interactions between them. Due to their size these small Ni-particles are superparamagnetic but dipolar coupling between them results in a ferromagnetic behavior of the whole system. Thus a semiconducting/ferromagnetic hybrid material with a broad range of magnetic properties can be fabricated. Furthermore this composite is an interesting candidate for silicon based applications and the compatibility with today’s process technology.
doi:10.1016/j.mee.2011.05.016
PMCID: PMC3242907  PMID: 22308049
Porous silicon; Electrodeposition; Magnetic nanostructures; Ferromagnetism
11.  Morphology and Photoluminescence of HfO2 Obtained by Microwave-Hydrothermal 
Nanoscale Research Letters  2009;4(11):1371-1379.
In this letter, we report on the obtention of hafnium oxide (HfO2) nanostructures by the microwave-hydrothermal method. These nanostructures were analyzed by X-ray diffraction (XRD), field-emission gum scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDXS), ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL) measurements. XRD patterns confirmed that this material crystallizes in a monoclinic structure. FEG-SEM and TEM micrographs indicated that the rice-like morphologies were formed due to an increase in the effective collisions between the nanoparticles during the MH processing. The EDXS spectrum was used to verify the chemical compositional of this oxide. UV–vis spectrum revealed that this material have an indirect optical band gap. When excited with 488 nm wavelength at room temperature, the HfO2 nanostructures exhibited only one broad PL band with a maximum at around 548 nm (green emission).
doi:10.1007/s11671-009-9407-6
PMCID: PMC2893942  PMID: 20628455
HfO2; Nanoparticles; Morphology; Optical band gap; Photoluminescence
12.  Morphology and Photoluminescence of HfO2Obtained by Microwave-Hydrothermal 
Nanoscale Research Letters  2009;4(11):1371-1379.
In this letter, we report on the obtention of hafnium oxide (HfO2) nanostructures by the microwave-hydrothermal method. These nanostructures were analyzed by X-ray diffraction (XRD), field-emission gum scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDXS), ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL) measurements. XRD patterns confirmed that this material crystallizes in a monoclinic structure. FEG-SEM and TEM micrographs indicated that the rice-like morphologies were formed due to an increase in the effective collisions between the nanoparticles during the MH processing. The EDXS spectrum was used to verify the chemical compositional of this oxide. UV–vis spectrum revealed that this material have an indirect optical band gap. When excited with 488 nm wavelength at room temperature, the HfO2nanostructures exhibited only one broad PL band with a maximum at around 548 nm (green emission).
doi:10.1007/s11671-009-9407-6
PMCID: PMC2893942  PMID: 20628455
HfO2; Nanoparticles; Morphology; Optical band gap; Photoluminescence
13.  The Effect of Sodium Dodecyl Sulfate (SDS) and Cetyltrimethylammonium Bromide (CTAB) on the Properties of ZnO Synthesized by Hydrothermal Method 
ZnO nanostructures were synthesized by hydrothermal method using different molar ratios of cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulfate (SDS) as structure directing agents. The effect of surfactants on the morphology of the ZnO crystals was investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) techniques. The results indicate that the mixture of cationic-anionic surfactants can significantly modify the shape and size of ZnO particles. Various structures such as flakes, sheets, rods, spheres, flowers and triangular-like particles sized from micro to nano were obtained. In order to examine the possible changes in other properties of ZnO, characterizations like powder X-ray diffraction (PXRD), thermogravimetric and differential thermogravimetric analysis (TGA-DTG), FTIR, surface area and porosity and UV-visible spectroscopy analysis were also studied and discussed.
doi:10.3390/ijms131013275
PMCID: PMC3497326  PMID: 23202952
zinc oxide; sodium dodecyl sulfate; cetyltrimethylammonium bromide; hydrothermal synthesis
14.  Hollow nitrogen-containing core/shell fibrous carbon nanomaterials as support to platinum nanocatalysts and their TEM tomography study 
Nanoscale Research Letters  2012;7(1):165.
Core/shell nanostructured carbon materials with carbon nanofiber (CNF) as the core and a nitrogen (N)-doped graphitic layer as the shell were synthesized by pyrolysis of CNF/polyaniline (CNF/PANI) composites prepared by in situ polymerization of aniline on CNFs. High-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared and Raman analyses indicated that the PANI shell was carbonized at 900°C. Platinum (Pt) nanoparticles were reduced by formic acid with catalyst supports. Compared to the untreated CNF/PANI composites, the carbonized composites were proven to be better supporting materials for the Pt nanocatalysts and showed superior performance as catalyst supports for methanol electrochemical oxidation. The current density of methanol oxidation on the catalyst with the core/shell nanostructured carbon materials is approximately seven times of that on the catalyst with CNF/PANI support. TEM tomography revealed that some Pt nanoparticles were embedded in the PANI shells of the CNF/PANI composites, which might decrease the electrocatalyst activity. TEM-energy dispersive spectroscopy mapping confirmed that the Pt nanoparticles in the inner tube of N-doped hollow CNFs could be accessed by the Nafion ionomer electrolyte, contributing to the catalytic oxidation of methanol.
doi:10.1186/1556-276X-7-165
PMCID: PMC3311096  PMID: 22385930
carbon nanofiber; N-doping; core/shell; polyaniline; catalyst support; methanol oxidation; TEM tomography
15.  Synthesis and Optical Enhancement of Amorphous Carbon Nanotubes/Silver Nanohybrids via Chemical Route at Low Temperature 
The Scientific World Journal  2014;2014:847806.
We report the synthesis of amorphous carbon nanotubes/silver (αCNTs/Ag) nanohybrids via simple chemical route without additional reactant and surfactant at low temperature. Field emission scanning microscope (FESEM) and transmission electron microscope (TEM) confirmed formation of CNTs. X-ray diffraction (XRD) pattern confirmed the amorphous phase of carbon and the formation of Ag nanoparticles crystalline phase. Raman spectra revealed the amorphous nature of αCNTs. UV-visible spectroscopy showed enhancement of optical properties of αCNTs/Ag nanohybrids.
doi:10.1155/2014/847806
PMCID: PMC4068040  PMID: 24995365
16.  Facile synthesis of SrCO3 nanostructures in methanol/water solution without additives 
Nanoscale Research Letters  2012;7(1):305.
Highly dispersive strontium carbonate (SrCO3) nanostructures with uniform dumbbell, ellipsoid, and rod-like morphologies were synthesized in methanol solution without any additives. These SrCO3 were characterized by X-ray diffraction, field emission scanning electron microscopy, and N2 adsorption-desorption. The results showed that the reaction temperature and the methanol/water ratio had important effects on the morphologies of SrCO3 particles. The dumbbell-like SrCO3 exhibited a Broader-Emmett-Teller surface area of 14.9 m2 g−1 and an average pore size of about 32 nm with narrow pore size distribution. The formation mechanism of the SrCO3 crystal was preliminary presented.
doi:10.1186/1556-276X-7-305
PMCID: PMC3460753  PMID: 22704526
Nanoparticle; Crystallization; SrCO3; Refluxing
17.  Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures 
Sensors (Basel, Switzerland)  2012;12(11):15424-15437.
In this study honeycomb-like NiO nanostructures were grown on nickel foam by a simple hydrothermal growth method. The NiO nanostructures were characterized by field emission electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The characterized NiO nanostructures were uniform, dense and polycrystalline in the crystal phase. In addition to this, the NiO nanostructures were used in the development of a zinc ion sensor electrode by functionalization with the highly selective zinc ion ionophore 12-crown-4. The developed zinc ion sensor electrode has shown a good linear potentiometric response for a wide range of zinc ion concentrations, ranging from 0.001 mM to 100 mM, with sensitivity of 36 mV/decade. The detection limit of the present zinc ion sensor was found to be 0.0005 mM and it also displays a fast response time of less than 10 s. The proposed zinc ion sensor electrode has also shown good reproducibility, repeatability, storage stability and selectivity. The zinc ion sensor based on the functionalized NiO nanostructures was also used as indicator electrode in potentiometric titrations and it has demonstrated an acceptable stoichiometric relationship for the determination of zinc ion in unknown samples. The NiO nanostructures-based zinc ion sensor has potential for analysing zinc ion in various industrial, clinical and other real samples.
doi:10.3390/s121115424
PMCID: PMC3522970  PMID: 23202217
honeycomb NiO nanostructures; potentiometric response; ion selective electrode; selectivity; selective ionophore
18.  Investigation of a Mesoporous Silicon Based Ferromagnetic Nanocomposite 
Nanoscale Research Letters  2009;5(2):374-378.
A semiconductor/metal nanocomposite is composed of a porosified silicon wafer and embedded ferromagnetic nanostructures. The obtained hybrid system possesses the electronic properties of silicon together with the magnetic properties of the incorporated ferromagnetic metal. On the one hand, a transition metal is electrochemically deposited from a metal salt solution into the nanostructured silicon skeleton, on the other hand magnetic particles of a few nanometres in size, fabricated in solution, are incorporated by immersion. The electrochemically deposited nanostructures can be tuned in size, shape and their spatial distribution by the process parameters, and thus specimens with desired ferromagnetic properties can be fabricated. Using magnetite nanoparticles for infiltration into porous silicon is of interest not only because of the magnetic properties of the composite material due to the possible modification of the ferromagnetic/superparamagnetic transition but also because of the biocompatibility of the system caused by the low toxicity of both materials. Thus, it is a promising candidate for biomedical applications as drug delivery or biomedical targeting.
doi:10.1007/s11671-009-9491-7
PMCID: PMC2894348  PMID: 20672039
Porous silicon; Nanocomposite; Magnetic nanoparticles
19.  Investigation of a Mesoporous Silicon Based Ferromagnetic Nanocomposite 
Nanoscale Research Letters  2009;5(2):374-378.
A semiconductor/metal nanocomposite is composed of a porosified silicon wafer and embedded ferromagnetic nanostructures. The obtained hybrid system possesses the electronic properties of silicon together with the magnetic properties of the incorporated ferromagnetic metal. On the one hand, a transition metal is electrochemically deposited from a metal salt solution into the nanostructured silicon skeleton, on the other hand magnetic particles of a few nanometres in size, fabricated in solution, are incorporated by immersion. The electrochemically deposited nanostructures can be tuned in size, shape and their spatial distribution by the process parameters, and thus specimens with desired ferromagnetic properties can be fabricated. Using magnetite nanoparticles for infiltration into porous silicon is of interest not only because of the magnetic properties of the composite material due to the possible modification of the ferromagnetic/superparamagnetic transition but also because of the biocompatibility of the system caused by the low toxicity of both materials. Thus, it is a promising candidate for biomedical applications as drug delivery or biomedical targeting.
doi:10.1007/s11671-009-9491-7
PMCID: PMC2894348  PMID: 20672039
Porous silicon; Nanocomposite; Magnetic nanoparticles
20.  Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM 
Summary
Focused-electron-beam-induced deposition (FEBID) is used as a direct-write approach to decorate ultrasmall Pt nanoclusters on carbon nanotubes at selected sites in a straightforward maskless manner. The as-deposited nanostructures are studied by transmission electron microscopy (TEM) in 2D and 3D, demonstrating that the Pt nanoclusters are well-dispersed, covering the selected areas of the CNT surface completely. The ability of FEBID to graft nanoclusters on multiple sides, through an electron-transparent target within one step, is unique as a physical deposition method. Using high-resolution TEM we have shown that the CNT structure can be well preserved thanks to the low dose used in FEBID. By tuning the electron-beam parameters, the density and distribution of the nanoclusters can be controlled. The purity of as-deposited nanoclusters can be improved by low-energy electron irradiation at room temperature.
doi:10.3762/bjnano.4.9
PMCID: PMC3566795  PMID: 23399584
carbon nanotubes; FEBID; nanocluster; platinum; patterning; radiation-induced nanostructures; TEM
21.  Synthesis of Novel Double-Layer Nanostructures of SiC–WOx by a Two Step Thermal Evaporation Process 
Nanoscale Research Letters  2009;4(8):802-808.
A novel double-layer nanostructure of silicon carbide and tungsten oxide is synthesized by a two-step thermal evaporation process using NiO as the catalyst. First, SiC nanowires are grown on Si substrate and then high density W18O49 nanorods are grown on these SiC nanowires to form a double-layer nanostructure. XRD and TEM analysis revealed that the synthesized nanostructures are well crystalline. The growth of W18O49 nanorods on SiC nanowires is explained on the basis of vapor–solid (VS) mechanism. The reasonably better turn-on field (5.4 V/μm) measured from the field emission measurements suggest that the synthesized nanostructures could be used as potential field emitters.
doi:10.1007/s11671-009-9318-6
PMCID: PMC2894364  PMID: 20596292
Silicon carbide; Tungsten oxide; Nanowires; Nanorods; Vapor–solid mechanism; Field emission
22.  Synthesis of Novel Double-Layer Nanostructures of SiC–WOxby a Two Step Thermal Evaporation Process 
Nanoscale Research Letters  2009;4(8):802-808.
A novel double-layer nanostructure of silicon carbide and tungsten oxide is synthesized by a two-step thermal evaporation process using NiO as the catalyst. First, SiC nanowires are grown on Si substrate and then high density W18O49nanorods are grown on these SiC nanowires to form a double-layer nanostructure. XRD and TEM analysis revealed that the synthesized nanostructures are well crystalline. The growth of W18O49nanorods on SiC nanowires is explained on the basis of vapor–solid (VS) mechanism. The reasonably better turn-on field (5.4 V/μm) measured from the field emission measurements suggest that the synthesized nanostructures could be used as potential field emitters.
doi:10.1007/s11671-009-9318-6
PMCID: PMC2894364  PMID: 20596292
Silicon carbide; Tungsten oxide; Nanowires; Nanorods; Vapor–solid mechanism; Field emission
23.  Dynamics of Electrochemical Lithiation/Delithiation of Graphene-Encapsulated Silicon Nanoparticles Studied by In-situ TEM 
Scientific Reports  2014;4:3863.
The incorporation of nanostructured carbon has been recently reported as an effective approach to improve the cycling stability when Si is used as high-capacity anodes for the next generation Li-ion battery. However, the mechanism of such notable improvement remains unclear. Herein, we report in-situ transmission electron microscopy (TEM) studies to directly observe the dynamic electrochemical lithiation/delithiation processes of crumpled graphene-encapsulated Si nanoparticles to understand their physical and chemical transformations. Unexpectedly, in the first lithiation process, crystalline Si nanoparticles undergo an isotropic to anisotropic transition, which is not observed in pure crystalline and amorphous Si nanoparticles. Such a surprising phenomenon arises from the uniformly distributed localized voltage around the Si nanoparticles due to the highly conductive graphene sheets. It is observed that the intimate contact between graphene and Si is maintained during volume expansion/contraction. Electrochemical sintering process where small Si nanoparticles react and merge together to form large agglomerates following spikes in localized electric current is another problem for batteries. In-situ TEM shows that graphene sheets help maintain the capacity even in the course of electrochemical sintering. Such in-situ TEM observations provide valuable phenomenological insights into electrochemical phenomena, which may help optimize the configuration for further improved performance.
doi:10.1038/srep03863
PMCID: PMC3900994  PMID: 24457519
24.  Carbon-assisted growth and high visible-light optical reflectivity of amorphous silicon oxynitride nanowires 
Nanoscale Research Letters  2011;6(1):469.
Large amounts of amorphous silicon oxynitride nanowires have been synthesized on silicon wafer through carbon-assisted vapor-solid growth avoiding the contamination from metallic catalysts. These nanowires have the length of up to 100 μm, with a diameter ranging from 50 to 150 nm. Around 3-nm-sized nanostructures are observed to be homogeneously distributed within a nanowire cross-section matrix. The unique configuration might determine the growth of ternary amorphous structure and its special splitting behavior. Optical properties of the nanowires have also been investigated. The obtained nanowires were attractive for their exceptional whiteness, perceived brightness, and optical brilliance. These nanowires display greatly enhanced reflection over the whole visible wavelength, with more than 80% of light reflected on most of the wavelength ranging from 400 to 700 nm and the lowest reflectivity exceeding 70%, exhibiting performance superior to that of the reported white beetle. Intense visible photoluminescence is also observed over a broad spectrum ranging from 320 to 500 nm with two shoulders centered at around 444 and 468 nm, respectively.
doi:10.1186/1556-276X-6-469
PMCID: PMC3211981  PMID: 21787429
25.  Investigation of In Vitro Drug Release from Porous Hollow Silica Nanospheres Prepared of ZnS@SiO2 Core-Shell 
In this contribution, porous hollow silica nanoparticles using inorganic nanosized ZnS as a template were prepared. The hydrothermal method was used to synthesize pure ZnS nanospheres material. The ZnS@SiO2 core-shell nanocomposites were prepared using a simple sol-gel method successfully. The hollow silica nanostructures were achieved by selective removal of the ZnS core. The morphology, structure, and composition of the product were determined using powder X-ray diffraction (XRD), emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). The results demonstrated clearly that the pure ZnS nanoparticles are in a spherical form with the average size of 40 nm and correspond with zinc blend structure. The porous hollow silica nanoparticles obtained were exploited as drug carriers to investigate in vitro release behavior of amoxicillin in simulated body fluid (SBF). UV-visible spectrometry was carried out to determine the amount of amoxicillin entrapped in the carrier. Amoxicillin release profile from porous hollow silica nanoparticles followed a three-stage pattern and indicated a delayed release effect.
doi:10.1155/2013/541030
PMCID: PMC3792506  PMID: 24170995

Results 1-25 (449618)