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1.
The hydrophobic gold nanostructures with different shapes were prepared by using n-butanol situ reduction in cetyltrimethylammonium bromide (CTAB)/n-butanol/n-heptane/HAuCl4(aq) W/O microemulsion through microwave dielectric heating. The CTAB-stabilized gold nanoparticles and nanowires with a networked structure obtained through this method were characterized and analyzed by ultraviolet visible spectroscopy (UV-vis), transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. The morphologies of the hydrophobic gold nanocrystals were successfully controlled through the adjustment of molar ratios of CTAB/HAuCl4 in the reverse microemulsion. The formation mechanism of anisotropic gold nanostructures was discussed, which demonstrated that CTAB played an important role in forming and stabilizing the shape of gold nanowires. 相似文献
2.
Phyllanthin-assisted biosynthesis of silver and gold nanoparticles: a novel biological approach 总被引:2,自引:0,他引:2
Abstract The anisotropic gold and spherical–quasi-spherical silver nanoparticles (NPs) were synthesized by reducing aqueous chloroauric
acid (HAuCl4) and silver nitrate (AgNO3) solution with the extract of phyllanthin at room temperature. The rate of reduction of HAuCl4 is greater than the AgNO3 at constant amount of phyllanthin extract. The size and shape of the NPs can be controlled by varying the concentration of
phyllanthin extract and thereby to tune their optical properties in the near-infrared region of the electromagnetic spectrum.
The case of low concentration of extract with HAuCl4 offers slow reduction rate along with the aid of electron-donating group containing extract leads to formation of hexagonal-
or triangular-shaped gold NPs. Transmission electron microscopy (TEM) analysis revealed that the shape changes on the gold
NPs from hexagonal to spherical particles with increasing initial concentration of phyllanthin extract. The Fourier transform
infrared spectroscopy and thermogravimetric analyses reveal that the interaction between NPs and phyllanthin extract. The
cyclic voltammograms of silver and gold NPs confirms the conversion of higher oxidation state to zero oxidation state.
Graphical abstract Anisotropic gold and silver nanoparticles were synthesized by a simple procedure using phyllanthin extract as reducing agent.
The rate of bioreduction of AgNO3 is lower than the HAuCl4 at constant concentration of phyllanthin extract. The required size of the nanoparticles can be prepared by varying the concentration
of phyllanthin with AgNO3 and HAuCl4.
相似文献
3.
Gold-Containing Nanocomposition Materials on the Basis of Homo- and Copolymers of Methylmethacrylate
N. O. Yakimovich N. V. Sapogova L. A. Smirnova A. P. Aleksandrov T. A. Gracheva A. V. Kirsanov N. M. Bityurin 《Russian Journal of Physical Chemistry B, Focus on Physics》2008,2(1):128-134
Films of polymethyl methacrylate and methyl methacrylate copolymers with ethylhexyl acrylate doped with HAuCl4 were subjected to UV irradiation followed by thermal treatment at various temperatures. The films were studied by absorption spectroscopy and small-angle X-ray scattering. The photolysis of HAuCl4 was found to result in the formation of gold nanoparticles, whose size depended on the structure of the polymeric matrix. An increase in the free volume of polymers caused the formation of larger particles. 相似文献
4.
A facile synthesis route is described for the preparation of a poly-(o-aminophenol)-gold nanoparticle composite material by polymerization of o-aminophenol (AP) monomer using HAuCl4 as the oxidant. The synthesis was carried out in a methanol medium so that it could serve a dual solvent role, a solvent
for both the AP and the water solution of HAuCl4. It was found that oxidative polymerization of AP leads to the formation of poly-AP with a diameter of 50±10nm, while the
reduction of AuCl4
- results in the formation of gold nanoparticles (∼ 2nm). The gold nanoparticles were uniformly dispersed and highly stabilized
throughout the macromolecular chain that formed a uniform metal-polymer composite material. The resultant composite material
was characterized by means of different techniques, such as UV-vis, IR and Raman spectroscopy, which offered the information
about the chemical structure of polymer, whereas electron microscopy images provided information regarding the morphology
of the composite material and the distribution of the metal particles in the composite material. 相似文献
5.
T. A. Gracheva T. A. Kuz’micheva V. N. Perevezentsev A. E. Mochalova L. A. Smirnova E. V. Salomatina 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(3):426-430
The kinetics of UV-induced formation of gold nanoparticles in polymethylmethacrylate films doped with chloroauric acid HAuCl4 is studied. The films are investigated by the absorption spectroscopy and smallangle X-ray scattering methods. The changing size and polydispersity of gold nanoparticles are analyzed during their formation. The growth of gold nanoparticles is determined by the properties of a polymeric matrix and the rate of diffusion fluxes of matter. 相似文献
6.
In this work, the fungus Penicillium was used for rapid extra-/intracellular biosynthesis of gold nanoparticles. AuCl4
− ions reacted with the cell filtrate of Penicillium sp. resulting in extracellular biosynthesis of gold nanoparticles within 1 min. Intracellular biosynthesis of gold nanoparticles
was obtained by incubating AuCl4
− solution with fungal biomass for 8 h. The gold nanoparticles were characterized by means of visual observation, UV–Vis absorption
spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive
X-ray spectroscopy (EDX). The extracellular nanoparticles exhibited maximum absorbance at 545 nm in UV–Vis spectroscopy. The
XRD spectrum showed Bragg reflections corresponding to the gold nanocrystals. TEM exhibited the formed spherical gold nanoparticles
in the size range from 30 to 50 nm with an average size of 45 nm. SEM and TEM revealed that the intracellular gold nanoparticles
were well dispersed on the cell wall and within the cell, and they are mostly spherical in shape with an average diameter
of 50 nm. The presence of gold was confirmed by EDX analysis. 相似文献
7.
In the present study Fe3O4 magnetic nanoparticles were synthesized by coprecipitation of Fe2+ and Fe3+ from chlorides. In the next step magnetite-gold core-shell nanoparticles were synthesized from HAuCl4 using an ethanol as a reducing agent. Finally, magnetic nanoparticles were functionalized by hexadecanethiol. The immobilization of biological molecules (trypsin and glucose oxidase) to the thiol-modified and unmodified magnetite-gold nanoparticles surface was tested. The resulting nanoparticles were characterized by infrared spectroscopy, differential scanning calorimetry, Mössbauer spectroscopy and transmission electron microscopy. 相似文献
8.
Ming Yang Xiao Yang Lufeng Huai 《Applied Physics A: Materials Science & Processing》2008,92(2):367-370
Hollow spheres and nanospheres of Au have been prepared by a simple reaction of HAuCl4·4H2O, NaOH and (NH2OH)2·H2SO4 in the presence of gelatin. The role of gelatin and the effect of the temperature of the reaction in producing the spherical
particles of Au are discussed. The products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy
and UV–Vis absorption spectroscopy. The sizes of the nanospheres of Au were estimated by the Debye–Scherrer formula according
to the XRD spectrum.
PACS 81.05.Bx; 81.05.Rm; 81.07.-b; 81.16.Be; 81.20.Fw 相似文献
9.
U?ur?Tamer Yusuf?Gündo?du ?smail?Hakk??Boyac? Kadir?Pekmez 《Journal of nanoparticle research》2010,12(4):1187-1196
The production of monodispersed magnetic nanoparticles with appropriate surface modification has attracted increasing attention
in biomedical applications including drug delivery, separation, and purification of biomolecules from the matrices. In the
present study, we report rapid and room temperature reaction synthesis of gold-coated iron nanoparticles in aqueous solution
using the borohydride reduction of HAuCl4 under sonication for the first time. The resulting nanoparticles were characterized with transmission electron microscopy
(TEM), electron spectroscopy for chemical analysis (ESCA), ultraviolet visible spectroscopy (UV–Vis), and X-ray diffraction
(XRD). Surface charges and magnetic properties of the nanoparticles were also examined. The pattern of Fe3O4 nanoparticles is face centered cubic with an average diameter of 9.5 nm and the initial reduction of gold on the surface
of Fe3O4 particles exhibits uniform Fe3O4–Au nanoparticles with an average diameter of 12.5 nm. The saturation magnetization values for the uncoated and gold-coated
Fe3O4 nanoparticles were found to be 30 and 4.5 emu/g, respectively, at 300 K. The progression of binding events between boronic
acid terminated ligand shell and fructose based on the covalent bonding interaction was measured by absorbance spectral changes.
Immunomagnetic separation was also performed at different E. coli concentration to evaluate capturing efficiency of resulting nanoparticles. Immunomagnetic separation percentages were varied
in a range of 52.1 and 21.9% depend on the initial bacteria counts. 相似文献
10.
Peng Jiang Jian-Jun Zhou Rui Li Yan Gao Tao-Lei Sun Xiao-Wei Zhao Yan-Juan Xiang Si-Shen Xie 《Journal of nanoparticle research》2006,8(6):927-934
PVP (poly(vinyl pyrrolidone))-capped micrometer-sized twinned gold (Au) plates with the shape of hexagon or triangle have been successfully synthesized in a large quantity by reducing hydrogen tetrachloroauric acid (HAuCl4·3H2O) using ethylene glycol in the presence of (PVP) molecules at 200°C under the extra condition of autogenous pressure. Clear twin boundaries in thus-obtained Au plates have been observed by scanning electron microscope (SEM). To further elucidate the mechanism of formation of the twinned Au plates, transmission electron microscopy (TEM) has been employed to characterize smaller Au nanoplates obtained simultaneously with the Au microplates, the occurrence of 1/3{422} forbidden reflections in selected area electron diffraction (SAED) can be believed to result from the presence of twinning boundary within the Au (111) plane normal to TEM electron beam. In addition, X-ray photoelectron spectroscopy (XPS) experiment has confirmed that PVP molecules exist on the surface of the Au cores, which may play a very important role in the formation and evolution of the twinned Au plates. A possible growth mechanism has been suggested to explain the Au plate evolution from nanometer to micrometer. 相似文献
11.
Composite Au/TiO2 nanoparticles were synthesized by laser ablation of gold plate in TiO2 sol. The nanoparticles were characterized by UV-visible spectroscopy, transmission electron microscopy, X-ray diffraction,
and atomic force microscopy. The peak of surface plasmon is at 550 nm with a red shift of 30 nm compared with that of Au nanoparticles
in water. Monolayers of composite Au/TiO2 nanoparticles were obtained by dip-coating technique. The XRD pattern of Au/TiO2 powders resembles a mixture of anatase TiO2 and gold. 相似文献
12.
Yu. Mikhlin M. Likhatski Ye. Tomashevich A. Romanchenko S. Erenburg S. Trubina 《Journal of Electron Spectroscopy and Related Phenomena》2010
The S L- and Au L3-edge X-ray absorption fine structure and X-ray photoelectron spectra of nanoscale Au–S products formed via the reduction of aqueous HAuCl4 by sulfide ions and immobilized onto graphite have been acquired. The TEY XANES and XPS spectra implied the formation of predominant polysulfide species and metallic gold, while the transmission spectra showed Au–S bonding, the share of which increased with increasing molar Na2S/HAuCl4 ratio in the reaction solution. The Au–S distances derived from EXAFS analysis changes from 2.31 Å to 2.325 Å with the concentration of sodium sulfide in solution, being longer than that for cuprite-type crystalline Au2S (2.174 Å). It has been concluded from all the evidence that the surface of gold sulfide decomposes in air and in ultra-high vacuum even before X-ray irradiation. 相似文献
13.
Metallic gold nanoparticles have been synthesized by the reduction of chloroaurate anions [AuCl4]− solution with hydrazine in the aqueous starch and ethylene glycol solution at room temperature and at atmospheric pressure.
The characterization of synthesized gold nanoparticles by UV–vis spectroscopy, high resolution transmission electron microscopy
(HRTEM), electron diffraction analysis, X-ray diffraction (XRD), and X-rays photoelectron spectroscopy (XPS) indicate that
average size of pure gold nanoparticles is 3.5 nm, they are spherical in shape and are pure metallic gold. The concentration
effects of [AuCl4]− anions, starch, ethylene glycol, and hydrazine, on particle size, were investigated, and the stabilization mechanism of Au
nanoparticles by starch polymer molecules was also studied by FT-IR and thermogravimetric analysis (TGA). FT-IR and TGA analysis
shows that hydroxyl groups of starch are responsible of capping and stabilizing gold nanoparticles. The UV–vis spectrum of
these samples shows that there is blue shift in surface plasmon resonance peak with decrease in particle size due to the quantum
confinement effect, a supporting evidence of formation of gold nanoparticles and this shift remains stable even after 3 months. 相似文献
14.
Jordi Llorca Albert Casanovas Montserrat Domínguez Ignasi Casanova Inmaculada Angurell Miquel Seco Oriol Rossell 《Journal of nanoparticle research》2008,10(3):537-542
Catalytically active gold nanoparticle films have been prepared from core-shell nanoparticles by plasma-activation and characterized
by high-resolution transmission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Methane
can be selectively oxidized into formic acid with an O2–H2 mixture in a catalytic wall reactor functionalized with plasma-activated gold nanoparticle films containing well-defined
Au particles of about 3.5 nm in diameter. No catalytic activity was recorded over gold nanoparticle films prepared by thermal
decomposition of core-shell nanoparticles due to particle agglomeration. 相似文献
15.
In this work, micro plasma-induced non-equilibrium liquid chemistry was utilized to synthesize and controlled formation of gold metallic nanoparticles (Au MNPs) by governing the concentration of (HAuCl4). These new approaches based on both plasma and liquid electrolytes contain charged species, and the interactions between the two phases represent a unique combination of physics, chemistry, and materials science. Continuous and stable DC glow discharge was done in home–made cavity to synthesize the definite sizes of (Au MNPs) by means of (3 kV) discharge voltage and (2 mA) discharge current for a period of (7 min) in aqueous solution of HAuCl4 with four different concentrations of about 1 mM, 5 mM, 10 mM and 20 mM at room temperature. The atmospheric pressure plasma discharge between stainless steel capillary tube cathode electrode over the (HAuCl4) solution and platinum plate as an anode dipped in solution for rapid formation of colloidal Au MNPs. Morphology aspects of the synthesized Au MNPs layer were studied by examining the (FE-SEM), HR-TEM images and X-ray difraction (XRD) pattern. Optical features of (Au MNPs) were considered via a UV–Vis beam spectrophotometer. These measurements showed that Au MNPs were organized by governing the concentration of HAuCl4, and uniform Au MNPs with specific exclusive sizes were acquired. Grain size, specific surface area and optical stability of Au MNPs strongly be affected by the HAuCl4 concentrations. 相似文献
16.
Chongjun Zhao Quanzhong Zhao Qitao Zhao Jianrong Qiu Congshan Zhu 《Applied Surface Science》2006,252(20):7415-7421
Au nanoparticles, which were photoreduced by a Nd:YAG laser in HAuCl4 solution containing TiO2 colloid and accompanied by the TiO2 particles, were deposited on the substrate surface. The film consisting of Au/TiO2 particles was characterized by the absorption spectra, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The adhesion between the film and substrate was evaluated by using adhesive tape test. It was found that the presence of TiO2 dramatically enhanced the adhesion strength between the film and the substrate, as well as the deposition rate of film. The mechanism for the deposition of Au/TiO2 film was also discussed. 相似文献
17.
Gold and gold-silver nanoparticles prepared by flame spray pyrolysis (FSP) were characterized by electron microscopy, in situ X-ray absorption spectroscopy (XANES and EXAFS), X-ray diffraction (XRD) and their catalytic activity in CO oxidation. Within this one-step flame-synthesis procedure, precursor solutions of dimethyl gold(III) acetylacetonate and silver(I) benzoate together with the corresponding precursor of the silica, iron oxide or titania support, were sprayed and combusted. In order to prepare small metal particles, a low noble metal loading was required. A loading of 0.1-1 wt.% of Au and Ag resulted in 1-6 nm particles. The size of the noble metal particles increased with higher loadings of gold and particularly silver. Both scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDXS) and X-ray absorption spectroscopy (XAS) studies proved the formation of mixed Au-Ag particles. In case of 1% Au-1% Ag/SiO2, TEM combined with electron spectroscopic imaging (ESI) using an imaging filter could be used in addition to prove the presence of silver and gold in the same noble metal particle. CO oxidation in the presence of hydrogen was chosen as a test reaction sensitive to small gold particles. Both the influence of the particle size and the alloying of gold and silver were reflected in the CO oxidation activity. 相似文献
18.
Douglas Fraser Yaez Ramon Ros Josep Marn Sergio de la Escosura-Muiz Alfredo Alegret Salvador Merkoi Arben 《Journal of nanoparticle research》2008,10(1):97-106
Simple strategies for producing silver and gold nanoparticles (AgNP and AuNP) along with the corresponding core shell nanoparticles (Au–Ag and Ag–Au) by reduction of the metal salts AgBF4 and HAuCl4 by NaBH4 in water will be presented. The morphologies of the obtained nanoparticles are determined by the order of addition of reactants. The obtained NPs, with sizes in the range 3–40 nm, are characterized by transmission electronic microscopy (TEM) and UV–Vis absorption spectroscopy, so as to evaluate their qualities. Moreover, a direct electrochemical detection protocol based on a cyclic voltammetry in water solution that involves the use of glassy carbon electrode is also applied to characterize the prepared NPs. The developed NPs and the related electroanalytical method seem to be with interest for future sensing and biosensing applications including DNA sensors and immunosensors. 相似文献
19.
S. Agouram J. Zuñiga Perez V. Muñoz-Sanjosé 《Applied Physics A: Materials Science & Processing》2007,88(1):83-87
The production of boron carbide (B4C) nanoparticles was investigated in a conventional high temperature furnace reactor. The reaction was carried out by heating a mixture of amorphous carbon and amorphous boron at 1550 °C to efficiently obtain a quantity of B4C. Scanning electron microscopy studies showed the average size of B4C particles was 200 nm, ranging from 50 nm to 350 nm. X-ray diffraction transmission electron microscopy and electron diffraction studies indicated that the prepared nanoparticles were crystalline B4C with a high density twin structure. High resolution transmission electron microscopy and selected area diffraction were also used to further characterize the structure of the prepared B4C particles, while energy dispersive spectroscopy and electron energy loss spectroscopy were used to determine the stoichiometry of the product. A solid state diffusion reaction mechanism is proposed. 相似文献
20.
A sensitive and selective electrochemical Pb2+ sensor consisting of a gold-carbon foam/chitosan/gold (Au-CFs/Chit/Au)-modified electrode was prepared. The electrode was synthesized via an oil-in-water emulsion polymerization and carbonization approach. Phenolic resins were used as a carbon source. HAuCl4 was used as a gold source and as an acidic catalyst. Melamine was used as a coordination and coupling agent to control the size of the Au nanoparticles (AuNPs). The morphologies and microstructures of the Au-CFs were characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The results revealed that the carbon foams contained interconnected macropores with diameters of nearly 5.0 μm and AuNPs with mean diameters of approximately 20.0, 9.0, and 7.0 nm. Brunauer–Emmett–Teller analysis revealed that the biggest surface area is 653.82 m2/g for Au/CFs-7. The electrochemical properties of modified electrodes and their responses to Pb2+ were characterized using cyclic voltammetry and differential pulse anodic stripping voltammetry. The influence of the test conditions were studied to optimize operational parameters such as the choice of supporting electrolyte, pH, deposition potential, and deposition time. Under optimal conditions, typical Au/CFs-7-modified gold electrodes exhibited an excellent electrochemical response for Pb2+ with a wide linear response range from 0.01 to 1.2 μM, a correlation coefficient of 0.995, and a lower limit of detection of 0.63 nM with deposition time of 180 s (S/N?=?3). 相似文献