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1.
A unique solution-phase route was devised to synthesize crystal Ag nanowires with high aspect-ratio (8-10 nm in diameter and length up to 10 μm) by the reduction of AgNO3 with Vitamin C in SDS/ethanol solution. The resultant nanoproducts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and electron diffraction (ED). A soft template mechanism was put forward to interpret the formation of metal Ag nanowires. 相似文献
2.
Lee YI Goo YS Chang CH Lee KJ Myung NV Choa YH 《Journal of nanoscience and nanotechnology》2011,11(2):1455-1458
Polycrystalline copper oxide nanostructures with different valence/oxidation states (i.e., Cu2O and CuO) were readily synthesized by thermal oxidation of single crystalline copper nanowires at relative low operating temperature (200 to 300 degrees C). Operating temperature of 200 to 250 degrees C in air oxidized copper to Cu2O and further increased temperature (i.e., 300 degrees C) led to form CuO nanostructures. The morphology of nanostructures significantly altered from nanowires to nanotubes which might be attributed to Kirkendall effect. The electrical resistivity of single copper nanowire, Cu2O and CuO nanotube were determined to be 3.4 x 10(-4), 33, and 211 omega cm, respectively. 相似文献
3.
《Materials Letters》2007,61(8-9):1711-1714
Pr(OH)3 nanorods with uniform diameter of 12 nm and different lengths ranging from 50 to 220 nm were successfully prepared via a facile and rapid microwave-assisted hydrothermal method. Pr6O11 nanorods were also obtained from calcination of the as-prepared hydroxide nanorods as precursors at 500 °C for 6 h. The results showed that the Pr(OH)3 with hexagonal phase and Pr6O11 nanorods with cubic phase have high crystallinity and purity. The mechanism for the microwave-assisted hydrothermal synthesis of Pr(OH)3 nanorods was preliminarily presented. 相似文献
4.
Synthesis of nanotubes and nanowires of silicon oxide 总被引:10,自引:0,他引:10
5.
Ni Liang Wang Lei Shao Bing Wang Yinjue Zhang Wenli Wang Chao Jiang Yong 《Materials Letters》2009,63(29):2560-2563
Copper oxalate nanowires with a mean diameter of 100 nm and a length of 10 µm were synthesized via the reaction of copper acetate and dimethyl oxalate in ether-water bilayer refluxing system. The volume ratio of ether to water and the concentration of copper acetate were used to examine the effects on forming copper oxalate nanowires. Copper oxalate nanowires were obtained only in the case of the greater volume ratio of ether to water and the lower concentration of copper acetate. Copper oxalate nanowires with a dense structure (enclosed by a smooth surface) can be further transformed into highly porous copper oxide nanowires by the decomposition of copper oxalate nanowires at 350 °C. 相似文献
6.
A low-cost and catalyst-free two-step approach has been developed to produce ZnO nanotubes (ZNTs) by simple thermal oxidation of Zn nanowires under 20?Pa at a low temperature of 400?°C. The growth mechanism of ZNTs is discussed in detail. The formation of these tubular structures is closely linked to the oxidation pressure and temperature, which involves a process consisting of the deposition of Zn nanowires, cracking of the Zn nanowires and sublimation of the Zn cores, and subsequent oxidation to ZNTs. The optical properties were studied by using Raman and photoluminescence spectra, where a strong green emission related to the single ionized oxygen vacancy appears. The photocatalytic activity measurement indicates an enhanced photocatalytic activity of the prepared ZNTs due to their high surface-to-volume ratios and abundant oxygen vacancies near the surfaces of the ZNTs. This type of high surface area structural ZNTs could find promising potential for optoelectronic and environmental applications. 相似文献
7.
High-quality single-crystalline CdS nanowires about 40 nm in diameter have been successfully synthesized without any catalyst at ambient pressure by combining the closed space sublimation (CSS) technique with porous anodic alumina membrane (AAM) template method. Extensive characterizations of the nanowires have been carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy and UV-Visible absorption spectroscopy. A band gap of 2.38 eV is determined from the UV-Vis absorption spectrum obtained from the nanowire sample. Our facile technique may in principle also be used for synthesizing other one-dimensional (1D) materials with high vapor pressure and axial nanowire heterostructures. 相似文献
8.
Liu XM Huang ZD Oh SW Ma PC Ma J Li BH Kim JK 《Journal of nanoscience and nanotechnology》2010,10(11):7378-7381
A new method for preparing black birnessite nanowires is introduced. Layer-structured manganese oxide nanowires were synthesized by a facile hydrothermal method, and using both NaMnO4 and CH3CH2OH as the precursors in a concentrated NaOH solution. The structure, composition, appearance and electrochemical performance of the product were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), energy diffraction (ED), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA) and constant current charge/discharge. The XRD patterns showed a single phase corresponding to a crystalline birnessite-based manganese oxide. TEM studies suggested their wire-like structures. The TGA measurement demonstrated that they possessed an excellent thermal stability up to 400 degrees C. In the potential window of 2.0-4.3 V, the product exhibited excellent cyclic stability and rapid charge-discharge performance. 相似文献
9.
Teh-Long Lai Yuan-Lung Lai Jen-Wei Yu Youn-Yuen Shu Chen-Bin Wang 《Materials Research Bulletin》2009,44(10):2040-2044
Coralloid nanostructured nickel hydroxide hydrate has been successfully synthesized by a simple microwave-assisted hydrothermal process using nickel sulfate hexahydrate as precursor and urea as hydrolysis-controlling agent. A pure coralloid nanostructured nickel oxide can be obtained from the nickel hydroxide hydrate after calcination at 400 °C. The thermal property, structure and morphology of samples were characterized by thermogravimetry (TG), temperature-programmed reduction (TPR), X-ray (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). 相似文献
10.
Zhang HB Chen C Wang JW Yang Y Lu ZH Yan Q Zheng WG 《Journal of nanoscience and nanotechnology》2011,11(12):10868-10870
High specific surface area graphene nanosheets have been obtained from graphite oxide by using an effective modified exfoliation method under vacuum, the exfoliation temperature (135 degrees C) is much lower than that conventionally applied (1050 degrees C) to obtain monolayer graphene sheets via rapid thermal shock. These products have fluffy and highly porous structure and with a lateral size typically of a few micrometers. Transmission electron microscopy (TEM) observation shows that it looks like a wrinkled transparent ultrathin film consisting of single or few-layer graphene sheets, and their Brunauer-Emmett-Teller surface area is as large as 750 m2/g. Simultaneously, X-ray photoelectron spectroscopy analysis revealed that considerable amount of oxygen-containing groups (C/O ratio, 5:1) retained on the graphene sheets after exfoliation process, which would provide convenience for further modification of the surface properties and chemistry of graphene sheets. This work offers a facile and scalable approach to fabricate graphene oxide and opens up a new vista of various potential applications electronics and composite materials. 相似文献
11.
Apte SK Garaje SN Mane GP Vinu A Naik SD Amalnerkar DP Kale BB 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(7):957-964
The simple, template-free, low-temperature, large-scale synthesis of nanostructured CdS with the hexagonal wurtzite phase from bulk cadmium oxide under solid-phase conditions is demonstrated for the first time. The novel approach involves the homogenization of cadmium oxide (CdO) and thiourea in various stoichiometric ratios at moderate temperature. Among the different molar ratios of CdO and thiourea studied, the CdO/NH(2) CSNH(2) molar ratio of 1:2 is found to be the best to obtain highly pure CdS. The obtained CdS nanostructures exhibit excellent cubic morphology and high specific surface area with a particle size in the range of 5-7 nm. The bandgap of the nanostructured CdS is in the range of 2.42 to 2.46 eV due to its nanocrystalline nature. In photoluminescence studies, emission is observed at 520.34 and 536.42 nm, which is characteristic of the greenish-yellow region of the visible spectrum. Considering the bandgap of the CdS is within the visible region, the photocatalytic activity for H(2) generation and organic dye degradation are performed under visible-light irradiation. The maximum H(2) evolution of 2945 μmol h(-1) is obtained using nanostructured CdS prepared in the 1:2 ratio, which is three times higher than that of bulk CdS (1010 μmol h(-1) ). CdS synthesized using the 1:2 molar ratio shows maximum methylene blue degradation (87.5%) over a period of 60 min, which is approximately four times higher than that of bulk CdS (22%). This amazing performance of the material is due to its nanocrystalline nature and the high surface area of the CdS. The proposed simple methodology is believed to be a significant breakthrough in the field of nanotechnology, and the method can be further generalized as a rational preparation scheme for the large-scale synthesis of various other nanostructured metal sulfides. 相似文献
12.
L.Z. Pei L.J. Yang Y. Yang C.G. Fan W.Y. Yin J. Chen Q.F. Zhang 《Materials Characterization》2010,61(11):1281-1285
Large-scale single crystalline calcium silicate nanowires have been synthesized via a simple and facile hydrothermal route using nanoscale SiO2 and CaO powders as the starting materials. Xonotlite [Ca6(Si6O17)(OH)2] nanowires were first achieved after hydrothermal treatment at 220 °C for 12 h. After being calcinated at 800 °C for 1 h, the Ca6(Si6O17)(OH)2 nanowires are completely transformed into β-CaSiO3 nanowires. The β-CaSiO3 nanowires have a diameter of 30–150 nm and a length of tens of micrometers. The hydrothermal conditions and the size of the raw materials play important roles on the size of the nanowires. A possible growth mechanism of the nanowires is also proposed. 相似文献
13.
Nanoporous Al2O3 with well-defined pore structure, crystallized framework and spherical morphology has been prepared by a facile template-free
approach, which involves the preparation via homogeneous precipitation and subsequent decomposition of spherical basic aluminium
sulphate particles. The particle size of the spheres can be tuned by controlling the holding time from the beginning of precipitation,
and a proper decomposition temperature is important to get high surface area, high pore volume and well-defined pore structures.
By the similar way, nanoporous ZrO2 and TiO2 spherical particles can also be prepared. These nanoporous oxides all have moderately high surface area (50–70 m2/g) and well-defined nanopores of around 4–12 nm with very narrow pore size distribution. The frameworks of these oxide spheres
consist of many small nanocrystallites, between which the nanopores exist. Compared with the soft and hard template routes,
this decomposition strategy of sulphates for nanoporous oxides has the advantages of simplicity and low cost. 相似文献
14.
Core-shell particles were prepared by the layer-by-layer (LbL) assembly of imogolite (IMO) nanotubes and poly(sodium 4-styrenesulfonate) (PSS) on polystyrene particles (diameter: 800 nm) coated preliminarily with poly(diallyldimethylammonium chloride) (PDDA). PSS and imogolite were alternately adsorbed on the particles to form core-shell particles with one to three bilayers of PSS/IMO. Macroporous hollow spheres were formed by removing polystyrene cores via heat treatment or extraction when the number of bilayers was 2 or 3. The sample formed by extraction (the number of bilayer was 3) showed only macroporosity and PSS remained in the shell, whereas the heat-treated sample showed hierarchical micro- and macroporosities. When the diameter of polystyrene particles decreased from 800 nm to 300 or 100 nm, hollow spheres were deformed because of the increase in the relative length of imogolite nanotubes against the size of polystyrene particles. Imogolite is a promising building block of hierarchically porous materials with core-shell morphologies using LbL assembly. 相似文献
15.
Limitations of cylindrical carbon nanotubes based on the buckminsterfullerene structure as delivery vehicles for therapeutic agents include their chemical inertness, sharp edges and toxicological concerns. As an alternative, we have developed lignin-based nanotubes synthesized in a sacrificial template of commercially available alumina membranes. Lignin is a complex phenolic plant cell wall polymer that is generated as a waste product from paper mills and biorefineries that process lignocellulosic biomass into fuels and chemicals. We covalently linked isolated lignin to the inner walls of activated alumina membranes and then added layers of dehydrogenation polymer onto this base layer via a peroxidase-catalyzed reaction. By using phenolic monomers displaying different reactivities, we were able to change the thickness of the polymer layer deposited within the pores, resulting in the synthesis of nanotubes with a wall thickness of approximately 15?nm or nanowires with a nominal diameter of 200?nm. These novel nanotubes are flexible and can be bio-functionalized easily and specifically, as shown by in vitro assays with biotin and Concanavalin A. Together with their intrinsic optical properties, which can also be varied as a function of their chemical composition, these lignin-based nanotubes are expected to enable a variety of new applications including as delivery systems that can be easily localized and imaged after uptake by living cells. 相似文献
16.
Yingkui Yang Shengqiang Qiu Wei Cui Qiang Zhao Xinjian Cheng Robert Kwok Yiu Li Xiaolin Xie Yiu-Wing Mai 《Journal of Materials Science》2009,44(17):4539-4545
Silica-coated multiwalled carbon nanotubes (MWCNTs) have been prepared by the sol–gel polymerization of tetraethoxysilane
(TEOS) in the presence of the acid-oxidized MWCNTs at room temperature, followed by oxidizing the MWCNTs templates at high
temperature in air to produce hollow silica nanotubes. The thickness and architectures of silica shell were well controlled
by rationally adjusting the concentration of TEOS, and by adding cationic surfactant as a structure-directing agent. These
results also give a clear answer to prove the fact that the structures of spherical silica particles can be fully “copied”
to the coating shell and the wall of silica nanotubes when prepared by the same method as the synthesis of silica particles
in the presence of templates. 相似文献
17.
Novel nanorod-assembling hollow nanowires of cadmium sulfide/DBTU (N,N′-dibutylthiourea) nanocomposite were synthesized by reacting CdCl2 with in situ produced H2S from reaction of butylamine and carbon disulfide at molar ratio 3:3 of CS2:BuNH2 at 50 °C. This product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SEAD), energy dispersive X-ray spectroscopy (EDAX), thermogravimetric (TG), Fourier transform infrared (FTIR) and UV-vis absorption spectra. A plausible mechanism that the extending DBTU molecules in solvent of CS2 induce the formation of CdS/DBTU nanorods by coordinating with the formed CdS particles, and construct these nanorods to hollow nanowires via molecular interactions is proposed and discussed on the basis of experimental results. Photoluminescence (PL) of CdS/DBTU nanocomposite exhibits increasing emission intensity largely. 相似文献
18.
Ling Liu 《Materials Letters》2010,64(19):2060-2063
Manganese carbonate (MnCO3) hollow dumbbells were synthesized via a polyol process. Based on the structural analysis of the samples obtained at different reaction times, a mechanism of nucleation-growth-aggregation-ripening was proposed to account for the formation of the hollow dumbbells. Moreover, the manganese oxide has also been obtained from the MnCO3 crystals after thermal transformation in laboratory air, and the phase of final product could easily be controlled to be either MnO2 or Mn2O3, simply by altering the calcination conditions. The manganese oxide powder products possessed mesoporosity and essentially preserved the pristine morphology of the MnCO3 precursor. 相似文献
19.
Superparamagnetic magnetite nanocrystals-graphene oxide (FGO) nanocomposites were successfully synthesized through a simple yet versatile one-step solution-processed approach at ambient conditions. Magnetite (Fe3O4) nanocrystals (NCs) with a size of 10-50 nm were uniformly deposited on the surfaces of graphene oxide (GO) sheets, which were confirmed by transmission electron microscopy (TEM) and high-angle annular dark field scanning transmission election microscopy (HAADF-STEM) studies. FGO with different Fe3O4 loadings could be controlled by simply manipulating the initial weight ratio of the precursors. The M-H measurements suggested that the as-prepared FGO nanocomposites have a large saturation magnetizations that made them can move regularly under an external magnetic field. Significantly, FGO nanocomposites also exhibit enhanced electric double-layer capacitor (EDLC) activity compared with pure Fe3O4 NCs and GO in terms of specific capacitance and high-rate charge-discharge. 相似文献
20.
《Journal of Experimental Nanoscience》2013,8(6):789-796
Hexagonal β-CuSCN hollow microspheres with average diameter 5?µm were successfully synthesised on a large scale via a decomposed reaction of the Cu(II)-dithizonate complex (Cu(HDZ)2). Examination of the produced microspheres as a function of the reaction time showed that the surface topography of the microspheres changed from a ragged surface to a smooth one. The synthetic products have been characterised by X-ray powder diffraction patterns, microscopy image and scanning electron microscopy. The optical properties were also investigated by the room temperature ultraviolet–visible absorption spectroscopy. Then, based on the observation, a possible formation process of hollow microspheres was proposed. 相似文献