Synthesis and characterization of copper nanoparticles

Reduction of copper salt by sodium citrate/SFS and myristic acid/SFS leads to phase pure Cu nanoparticles. However, a similar reaction with hydrazine hydrate (HH) and sodium formaldehyde sulfoxylate (SFS) in polymer afforded only a mixture of Cu₂O and Cu. Copper nanoparticles so-prepared were characterized by UV-Visible spectroscopy, X-ray diffraction measurements (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Freshly prepared solutions showed an absorption band at about 600 nm due to surface plasmon resonance (SPR). XRD analysis revealed all relevant Bragg's reflection for fcc crystal structure of copper metal. The particle size by use of Scherrer's equation is calculated to be about 30 nm. TEM showed nearly uniform distribution of the particles in PVA.     

Parametric study of cost-effective synthesis of crystalline copper nanoparticles and their crystallographic characterization

Pure and high-crystalline copper nanoparticles were synthesized at room temperature by reduction of copper nitrate with hydrazine hydrate in cetyltrimethyl ammonium bromide (CTAB) solution without using any extra gases. A parametric study has been carried out in terms of hydrazine concentration, solution pH, and stirring. Pure copper nanoparticles without oxidation were obtained at 0.1–0.2 M N₂H₄ and pH = 10. The growth mechanism of various shaped copper nanoparticles is discussed based on structural analysis by transmission electron microscopy and selected area electron diffraction.     

Bacterial synthesis of copper/copper oxide nanoparticles

A bacterial mediated synthesis of copper/copper oxide nanoparticle composite is reported. A Gram-negative bacterium belonging to the genus Serratia was isolated from the midgut of Stibara sp., an insect of the Cerambycidae family of beetles found in the Northwestern Ghats of India. This is a unique bacterium that is quite specific for the synthesis of copper oxide nanoparticles as several other strains isolated from the same insect and common Indian mosquitoes did not result in nanoparticle formation. By following the reaction systematically, we could delineate that the nanoparticle formation occurs intracellularly. However, the process results in the killing of bacterial cells. Subsequently the nanoparticles leak out as the cell wall disintegrates. The nanoparticles formed are thoroughly characterized by UV-Vis, TEM, XRD, XPS and FTIR studies.     

Nonaqueous phase synthesis of copper nanoparticles

Copper nanoparticles were synthesized in a nonaqueous solution of cetyltrimethylammonium bromide with isopropanol as a solvent. Cetyltrimethylammonium bromide in isopropanol is observed to play a role as a catalyst where isopropanol is the reducing agent. The surface plasmon band characteristic for Cu nanoparticles can be observed at approximately 560 nm in the UV-visible spectra at molar ratios for Cu2+: cetyltrimethylammonium bromide of 1:15 and 1:30. On the other hand, at molar ratios of 1:0.25 and 1:1 the presence of peak at approximately 310 nm can be attributed to oligomeric clusters of Cu0. Formation of Cu0 was further confirmed from the X-ray diffraction analysis. The diffractograms exhibited peaks at 2theta = approximately 41.6 degrees, approximately 51.6 degrees, and approximately 74.3 degrees, corresponding to Cu0. At lower concentration of cetyltrimethylammonium bromide (i.e., Cu2+: cetyltrimethylammonium bromide = 1:0.25) higher degree of size dispersity (particles between approximately 5-20 nm) can be noted from transmission electron micrograph. On the other hand, at the highest concentration of cetyltrimethylammonium bromide (i.e., Cu2+: cetyltrimethylammonium bromide = 1:30), formation of finer sized particles with a lower degree of size variation, approximately 2-10 nm, can be observed.     

Simple new synthesis of copper nanoparticles in water/acetonitrile mixed solvent and their characterization

Copper nanoparticles were successfully synthesized by the borohydride reduction of copper nitrate salt in water/CH₃CN mixed solvent under inert argon-purged conditions. Cu nanoparticles were synthesized in large-scale production for the first time by introducing CH₃CN into water and preventing oxidation during the preparation of nanoparticles. Nanoparticles were characterized by using UV-visible absorption spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. High resolution TEM pictures showed the formation of homogeneous cubic-structured copper nanoparticles with sizes less than 100 nm. This new kind of synthesis method shows the excellent stability compared with that of citrate-protected copper nanoparticles, which may provide an efficient way to improve the fine tuning of the structure and size of copper nanoparticles.     

Rapid synthesis and characterization of maghemite nanoparticles

Fe2O3-SiO2 nanocomposites were prepared by a sol-gel method using various evaporation surface to volume (S/V) ratios ranging from 0.03 to 0.2. The Fe2O3-SiO2 sols were gelated at various temperatures ranging from 50 degrees C to 70 degrees C, and subsequently they were calcined in air at 400 degrees C for 4 hours. The structure and the magnetic properties of the prepared Fe203-SiO2 nanocomposites were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), differential thermal analysis (DTA), and vibrating sample magnetometer (VSM) measurements. The gelation temperature of the Fe2O3-SiO2 sols influenced strongly the particle size and crystallinity of the maghemite nanoparticles. It was observed that the particle size of maghemite nanoparticles increased with the increasing of the gelation temperature of the sols, which may be due to the agglomeration of the maghemite particles at elevated temperatures inside the microporosity of the silica matrix during the gelation process, and the subsequent calcination of these gels at 400 degrees C resulted in the formation of large size iron oxide particles. Magnetization studies at temperatures of 10, 195, and 300 K showed superparamagnetic behavior for all the nanocomposites prepared using the evaporation surface to volume ratio (S/V) of 0.1, 0.2, 0.09, and 0.08. The saturation magnetization, Ms, values measured at 10 K were 5.5, 8.5, and 9.5 emu/g, for the samples gelated at 50, 60, and 70 degrees C, respectively. At the gelation temperature of 70 degrees C, gamma-Fe2O3 crystalline superparamagnetic nanoparticles with the particle size of 9 +/- 2 nm were formed in 12 hours for the samples prepared at the S/V ratio of 0.2.     

Sonochemical synthesis and characterization of disk-like copper microcrystals

Disk-like Cu microcrystals were successfully synthesized with assistance of ultrasonic irradiation. The products were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and thermogravimetric/differential thermal analysis (TGA/DTA). It was found that as-prepared Cu microcrystals were single crystals in nature and had a high crystallinity. They were mainly composed of disk-like and triangular Cu microcrystals with an average diameter of about 1 μm. There existed CuO on the outermost surface of the products, while a thin layer of Cu₂O was found between CuO and inner Cu microcrystals. Moreover, CTAB molecules were adsorbed on the surface of Cu microcrystals and they were desorbed while heated during TGA analysis. In addition, the influences of magnetic stirring, stillness, concentration of hexadecyltrimethylammonium bromide (CTAB) surfactant, and starting Cu salts on the morphology and size distribution of the final products have also been studied.     

纳米二氧化铈的电化学制备与表征

在铈盐溶液中用电解的方法制备了CeO2 纳米粉体。X 射线衍射表明 ,所得产物为立方晶系CeO2 ;SEM分析表明 ,CeO2 纳米粒子呈球形 ,晶粒度约 10nm ;TEM分析表明 ,粒径分布均匀 ,粒子不发生团聚 ;电子衍射表明 ,CeO2 纳米粒子为多晶结构。实验探讨了溶液浓度、电流密度等因素对CeO2 质量和产量的影响     

Microwave-assisted synthesis and characterization of tin oxide nanoparticles

Tin oxide nanoplatelets (SnO) and nanoparticles (SnO₂) were prepared by microwave assisted technique with an operating frequency of 2.45 GHz. This technique permits to produce gram quantity of homogeneous nanoparticles in just 10 min. The crystalline size was evaluated from XRD and found to range from 26 to 34 nm. SEM and TEM analyses showed that the nanoparticles present a platelet-like shaped particle or, a pseudo spherical morphology, after calcination at moderate temperature during which the phase transformation from SnO to SnO₂ takes place. Additional FT-IR, density and resistivity measurements were also presented.     

One-step synthesis of copper nanoparticles embedded in carbon composites

Copper nanoparticles embedded in carbon composites were prepared via spray pyrolysis by adjusting the polyvinylpyrrolidone (PVP) to copper nitrate mass ratio. When the equal amount of two precursors was mixed and spray pyrolyzed, copper nanoparticles with sizes in the range 30–50 nm were incorporated into the carbon composites arising from PVP. X-ray photoelectron spectroscopy demonstrated that the copper nanoparticles exhibit oxidation resistance. In addition, the effects of carbon on the surface plasmon bands were investigated. This synthetic process is simple and environmentally friendly and reduces the problems associated with their oxidation through one-step passivation.     

Chemical synthesis and characterization of amorphous Fe-Ni-B magnetic nanoparticles

We have synthesized Fe-Ni-B amorphous nanoparticles by chemical reduction of the transition metal solution. A compositional study shows that the nominal Ni/Fe ratio is preserved. The new preparation method used yields a much higher boron composition than the one obtained traditionally by rapid quenching and other chemical synthesis previously reported. For all compositions, the size of the particles is about 2.1 nm diameter with a narrow log-normal distribution.     

Hydrothermal synthesis of zirconium oxide nanoparticles and its characterization

The paper presents the preparation and investigations of zirconium oxide (ZrO₂) nanoparticles that were synthesized by hydrothermal method. The products were characterized by means of powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-absorption spectroscopy and photoluminescence (PL) spectroscopy. The crystal structure was determined using X-ray diffraction. The morphology and the particle size were studied using (SEM) and (TEM). The spherical shaped particles were confirmed through the SEM analysis. The transmission electron microscopic analysis confirmed the formation of the nanoparticles with the particle size. The FT-IR and Raman spectrum ascertained the strong presence of ZrO₂ nanoparticles. The optical properties were obtained from UV–visible absorption spectrum and also PL emission spectrum. The dielectric constant and the dielectric loss were measured as a function of frequency and temperature.     

Synthesis and optical characterization of copper nanoparticles prepared by laser ablation

The remarkable size-tunable properties of nanoparticles (NPs) make them a hot research topic with applications in a wide range of fields. Hence, copper (Cu) colloidal NPs were prepared using laser ablation (Nd:YAG, 1064 nm, 7 ns, 10 Hz, 6000 pulses) of a copper metal plate at different laser fluences (LFs) in the range of 1–2.5 J cm^?2 in ethylene glycol (EG), at room temperature. Analysis of NPs was carried using different independent techniques such as ultraviolet–visible (UV–vis) spectroscopy; transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. TEM analysis showed that the NPs were spherical with a bimodal distribution and an average particle size of 5 and 16 nm influence of 1.2 J cms^?2, and 9 and 22 nm at 2 J cm^?2. The UV–vis spectra of colloidal NPs revealed the maximum absorbance at around 584 nm, indicating the formation of Cu NPs, which supported using FTIR spectra. Furthermore, the absorption spectra confirmed the metallic nature of Cu NPs. FTIR spectroscopy was utilized to verify information about the NPs surface state and chemical bonds constructed in the atom groups apparent on their surface.     

Colloidal synthesis of copper nanoparticles in a two-phase liquid-liquid system

Synthesis of copper nanoparticles in a two-phase, toluene-water system was investigated. The synthesis involves a transfer of metal cations from the aqueous phase to the toluene phase through the use of tetraoctylammonium bromide, a phase transfer reagent. Subsequently, the metal cations were reduced using sodium borohydride in the presence of oleylamine, a stabilizing ligand. Due to the high tendency of copper to oxidize in air, the syntheses and post-synthesis treatments were carried out in an inert atmosphere, N₂. Non-agglomerated, generally spherical, copper nanoparticles with a mean size of 6.06 nm were successfully made using the technique. By analyzing the lattice d spacing of HRTEM images, the crystal structure of the particles was found to be FCC. The expected plasmon resonance peak for copper, 570 nm, was missing from UV/Vis spectroscopy analysis; this has been attributed to quenching due to residual CuBr.     

Calcium carbonate nanoparticles: synthesis, characterization and biocompatibility

The synthesis of nanoparticles and their functionalization to effectively utilize them in biological applications including drug delivery is currently a challenge. Calcium carbonate among many other inorganic nanosized particles offers promising results for such applications. We have synthesized calcium carbonate nanoparticles using polymer mediated growth technique, where one of the ions bound within polymer matrix and the other diffuses and reacts to form desired compound. The synthesized nanoparticles are characterized using X-ray diffraction, Scanning Electron Microscopy and spectroscopic techniques such as Fourier-Transform Infra-red spectroscopy and UV-Vis spectroscopy. The diameter of the calcium carbonate nanoparticles is estimated to be 39.8 nm and their biocompatibility studies showed no significant induction of oxidative stress or cell death even at higher concentrations (50 microg) upon exposure to HeLa and LE cells. Here, we report that the synthesized calcium carbonate nanosized particles using polymer mediated growth technique are biocompatible and can be safely used for biomedical applications.     

Silver nanoparticles in hyperbranched polybenzobisthiazole: synthesis and characterization

Silver (Ag) nanoparticles were successfully synthesized in hyperbranched polybenzobisthiazoles (HBPBZTs) matrices using a reductive technique. The synthesized Ag nanoparticles were characterized through different spectroscopic and analytical techniques, such as FTIR, XRD, TGA, TEM, UV-vis, and fluorescence spectra. The results showed that the synthesized Ag-HBPBZT nanocomposites exhibited excellent thermostability and the Ag nanoparticles represented face-centered cubic crystal structures. It was interesting that these nanoparticles were soluble in DMSO. The Ag nanoparticles prepared using amino and sulfydryl-terminated HBPBZT (hbp3) as template and stabilizer had smaller sizes, more regular shapes, and narrower size distributions than those prepared using hbpl and hbp2 as templates and stabilizers. The Ag-HBPBZT nanocomposites had UV-vis absorptions at approximately 341 nm to 361 nm which were attributable to the surface plasmon resonance of the Ag nanoparticles. These nanocomposites emitted a strong blue light in DMSO solution. The prepared Ag-HBPBZT nanocomposites are potentially useful in the area of blue light emission.     

双氮二甲基甲酰胺介导溶剂热合成CuS粉体及表征

以CuCl2.2H2O为铜源,N,N-二甲基甲酰胺(N,N-dimethylformamide,DMF)为溶剂,分别以L-半胱氨酸、硫脲、硫代乙酰胺为硫源采用溶剂热法在130℃下反应8h得到了不同形貌的硫化铜(CuS)纳米粉体。用X射线粉末衍射仪、X射线光电子能谱、场发射扫描电子显微镜、透射电子显微镜、紫外可见吸收光谱手段对粉体的结构、形貌、成分及光学性能进行表征。研究表明,硫源对产物的结构和形貌有较大的影响。采用L-半胱氨酸为硫源得到的产物多呈纳米颗粒无序堆积的无定形态,而采用硫脲和硫代乙酰胺为硫源得到的是纳米棒组成的球状粉体。讨论了不同硫源对CuS粉体的形成及其形貌的影响,并对各种形貌CuS粉体的形成机理进行了简单的探讨。     

Controllable synthesis and characterization of novel copper-carbon core-shell structured nanoparticles

A facile hydrothermal method was developed for preparing copper-carbon core-shell structured particles through a reaction at 160 °C in which glucose, copper sulfate pentahydrate and cetyltrimethylammonium bromide were used as starting materials. The original copper-carbon core-shell structured particles obtained were sized of 100-250 nm. The thickness of carbonaceous shells was controlled ranging from 25 to 100 nm by adjusting the hydrothermal duration time and the concentrations of glucose in the process. Products were characterized with transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier transform infrared spectroscopy. Since no toxic materials were involved in the preparation, particles with stable carbonaceous framework and reactive surface also showed promising applications in medicine, electronics, sensors, lubricant, etc.     

Facile synthesis of magnetic iron oxide nanoparticles and their characterization

Magnetic iron oxide nanoparticles are synthesized by suitable modification of the standard synthetic procedure without use of inert atmosphere and at room temperature. The facile synthesis procedure can be easily scaled up and is of important from industrial point of view for the commercial large scale production of magnetic iron oxide nanoparticles. The synthesized nanoparticles were characterized by thermal, dynamic light scattering, scanning electron microscopy and transmission electron microscopy analyses.