Controllable synthesis of pentagonal silver nanowires via a simple alcohol-thermal method

Pentagonal silver nanowires with diameters in range of 20-40 nm, and lengths up to ~ 10 µm were successfully synthesized via a simple and effective alcohol-thermal route. These nanowires were prepared by reducing silver nitrate in ethanol solution with dodecylamine which acted as complexing, reducing and capping agent. The molar ratio of dodecylamine to AgNO₃ played an important role in controlling aspect ratio of the products. Samples were characterized in detail by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) technologies. UV-vis absorption spectrum of the nanowires in solution has been taken to study their optical properties. Based on the analysis of the experimental results, the possible formation mechanism of nanowires was proposed as well.     

Shape-controlled synthesis of polypyrrole/Ag nanostructures in the presence of chitosan

Polypyrrole (PPy)-coated Ag nanoparticles and nanowires were fabricated through the redox reaction between pyrrole monomer and silver nitrate in the presence of chitosan. The morphologies, compositions, and electrochemical activities of PPy/Ag composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Cyclic voltammetry. The synthetic route employed here is simple and inexpensive and can be extended to prepare other conducting polymer/inorganic nanocomposites.     

Effects of morphology and cesium promotion over silver nanoparticles catalysts in the styrene epoxidation

Silver nanowires have been obtained by polyol reduction of silver nitrate in presence of polyvinyl-pyrrolidone (PVP). The as-synthesized silver nanowires were deposited on α- Al₂O₃. For comparison silver catalysts were also prepared by wetness impregnation obtaining irregularly shaped silver particles. Epoxidation of styrene to styrene oxide (SO) by molecular oxygen was studied using the silver catalysts. The main products were styrene oxide (SO) and phenylacetaldehyde (Phe). The promotion effect of the Cs on the silver nanowires catalysts was investigated. The Cs loading was in the range of 0–1 wt.% (refereed to silver). Furthermore, the effect of O₂:C₈H₈ molar ratio on the catalytic epoxidation was also investigated. Silver nanowires catalysts showed superior catalytic activity compared to those prepared by impregnation method. Besides, higher O₂:C₈H₈ ratios improved the selectivity to SO. The catalytic activity showed a maximum performance for silver nanowires promoted with 0.25 wt.% of Cs, achieving 94.6% of conversion and total selectivity to desired oxidation products (styrene oxide and phenylacetaldehyde). Moreover, the cesium promotion also contributed to the increase in the selectivity to styrene oxide. Temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) were employed to detect the presence of different species of oxygen in the catalysts indicating that subsurface oxygen was beneficial for the epoxidation. The samples were also structurally characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible absorption spectra and selected area electron diffraction pattern (SAED).     

化学还原法合成均匀银纳米线的条件研究

采用化学还原法,以乙二醇为还原剂,聚乙烯砒咯烷酮(PVP K30)为表面活性剂,通过还原硝酸银(AgNO3)溶液直接制备了高浓度的Ag纳米线溶液,并研究了PVP与AgNO3溶液摩尔浓度比和AgNO3溶液浓度对Ag纳米线生长的影响.用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对纳米Ag晶体的生长形貌进行了比较,利...     

纳米Co-Mn-Al-CO_3层状双金属氢氧化物的合成及表征

以过渡金属盐Co(NO3)2、Mn(NO3)2为钴源、锰源,Al(NO3)3为铝源,NaOH和Na2CO3混合溶液为碱性介质,利用共沉淀法分别制备了n(Co)∶n(Mn)∶n(Al)=4∶0∶2、4∶1∶1、4∶2∶0的CO32-离子插层纳米层状双金属氢氧化物(LDHs)。利用X射线衍射(XRD)、X射线荧光光谱分析(XRF)、N2吸附脱附、透射电镜(TEM)技术对样品进行了表征。结果表明,样品呈层状片状,随着LDHs样品中Mn、Al原子比的增加,结晶度变差,形貌变得无序,平均孔径减小,比表面积和孔道容量变大。     

Synthesis of single-crystalline silver sulfide nanowires by diffusion in porous anodic aluminium oxide template

Highly ordered single-crystalline silver sulfide (Ag₂S) nanowires have been successfully achieved directly using silver nitrate and thioacetamide (TAA) as the reactants, by diffusion in the channels of anodic aluminium oxide (AAO) membrane. The products have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The results of the research show that the as-prepared Ag₂S nanowires are monodisperse with sizes of about 50 nm in diameter, closely corresponding to the pore size of the AAO membrane. Furthermore, its photoluminescence properties and the growth mechanism are also discussed.     

Polyurethane–silver fibers prepared by infiltration and reduction of silver nitrate

Silver-incorporating polyurethane fibers were prepared by infiltration of silver nitrate on electrospun polyurethane fibers and reduction with sodium borohydride. They were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray system. The Ag nanoparticles prepared by reduction of silver nitrate showed nano-sized crystals of 4–10 nm in diameter. However, larger aggregated Ag particles of 50–200 nm were also found to be dispersed in the polyurethane matrix when Ag particles were formed in electrospun fibers by the infiltration–reduction process of silver nitrate. As a result, infiltration method of silver nitrate into the electrospun fibers was significantly effective to produce silver-incorporating fibers due to a high specific surface area of fibers.     

SnO_2纳米线的合成与结构表征

采用化学气相沉积法在经表面活性剂与硝酸镍的混合溶液处理过的硅衬底上成功制备出了直径均匀可控的二氧化锡(SnO2)纳米线。利用扫描电子显微镜、透射电子显微镜、选区电子衍射、X射线衍射等手段对样品的表面形貌、微结构及成分等进行了表征分析。并在此基础上讨论了纳米线所遵循的生长机理。     

Facile synthesis of reduced graphene oxide nanosheets by a sodium diphenylamine sulfonate reduction process and its electrochemical property

We report a new method to convert graphene oxide (GO) to stable colloidal dispersion of reduced graphene oxide nanosheets (RGONS) using sodium diphenylamine sulfonate (SDAS) as a reductant, as well as itself and its redox product as the stabilizer. The as-prepared RGONS have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, UV–visible spectroscopy, thermo-gravimetric analysis, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy and Raman spectroscopy. The results indicate that the bulk of oxygen-containing functional groups from GO have been removed. Based on the cyclic voltammogram (CV) analyses, it is found that the RGONS-based material exhibits better electrochemical activity in sensing ascorbic acid than GO. The simple method provides a new efficient route for the synthesis of water-soluble RGONS on a large scale and novel composites.     

油浴中多羟基还原法快速合成银纳米线

通过简单的油浴加热法,在没有保护气体的氛围中,利用乙二醇还原硝酸银并在聚乙烯吡咯烷酮存在的条件下合成银纳米结构材料。采用扫描电子显微镜和X射线光谱表征产物。分析讨论了聚乙烯吡咯烷酮和银离子的浓度比等对最终纳米结构产物的影响,结果表明,当它们浓度比为1时,溶液中引入微量的氯离子就可以合成出大量的银纳米线。最后探讨了纳米线的合成机理。     

空制剂中金属离子对多元醇热法制备纳米银线的影响

以含有不同金属离子的Cl盐晶体为控制剂,采用多元醇热法制备高性能的银纳米线,通过SEM、TEM、SAED和XRD对不同条件下的Ag产物形貌和结构进行比较,研究了控制剂中不同金属离子对AgNWs一维生长均匀性和纯度的影响,结果表明,在含Fe卦控制剂Fecl3·6H2O0作用下,且浓度相同,反应时间为40min即可制得高纯度高长径比的AgNWs,说明强还原性金属离子对制备高性能银纳米线有优化促进作用,从而提高AzNWs的合成效率。     

Synthesis of nearly monodispersive gold nanoparticles by a sodium diphenylamine sulfonate reduction process

Au nanoparticles have been prepared by the reaction of HAuCl₄ and sodium diphenylamine sulfonate in the presence/absence of poly(vinylpyrrolidone)(PVP) at room temperature. The nanoparticles were characterized by Transmission electron microscopy (TEM), UV-Vis absorption spectrum. The research showed that the molar ratio of PVP/ HAuCl₄ has effect on the size and the morphology of Au nanoparticles.     

Silver nanorods using HEC as a template by γ-irradiation technique and absorption dose that changed their nanosize and morphology

Silver (Ag) nanorods with average diameters of 20 nm and lengths up to 250 nm were successfully prepared in large scale using hydroxyethyl cellulose (HEC) as a template reducing silver nitrate by γ-irradiation. When we changed the irradiation time to get a different absorption dose at the same dose rate, we can find that the silver nanorods have been transferred into a larger size and another morphology. The particle size and morphology can be changed by choosing different absorption doses under the same dose rate. The products were characterized by transmission electron microscopy (TEM), electron diffraction (ED) analysis, field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).     

Flash synthesis of flower-like ZnO nanostructures by microwave-induced combustion process

Flower-like ZnO particles were fabricated from zinc nitrate and urea via the microwave-induced combustion technique (MICT). The structure and morphology of the products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The effects of growth conditions such as microwave power, radiation time, and molar ratio of urea/Zn²⁺ were investigated. Results show that the morphologies and particle sizes of the final products depend on the molar ratio of urea/Zn²⁺. The SEM images of ZnO flowers grown in different periods were employed to explain the formation mechanism. This study provides a simple and efficient approach for synthesizing flower-like ZnO heterostructures.     

A facile synthesis of novel nanorod-assembling hollow nanowires of cadmium sulfide/DBTU nanocomposite

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.     

Synthesis and characterization of AgO nanostructures by precipitation method and its photocatalyst application

In this research, a precipitation method was used in order to synthesize AgO nanostructures with the aid of silver nitrate as the starting reagent in an aqueous solution. To examine the effect of different surfactants such as glucose, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and cetyltrimethylammonium bromide on the morphology and particle size of final products several tests were performed. The structural, morphological, and optical properties of as-obtained products were characterized by techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and ultraviolet–visible spectroscopy. Furthermore, the hysteresis loop measured at room temperature shows a ferromagnetic behavior of the AgO nanostructures. To evaluate the catalytic properties of nanocrystalline silver oxide (AgO), the photocatalytic degradation of rhodamine-B under visible light irradiation was carried out.     

Zn(1-x)Mg(x)Te nanowires grown by solid source molecular beam epitaxy

This paper reports on the epitaxial growth of single-crystalline ternary Zn(1-x)Mg(x)Te nanowires covering a broad compositional range of molar fraction 0≤x≤0.75. The nanowires were grown on (100), (110), and (111) GaAs substrates using a vapor-liquid-solid mechanism. Solid source molecular beam epitaxy and an Au-based nanocatalyst were used for these purposes. The composition of nanowires can be adjusted by changing the ratio of Mg to Zn molecular beam fluxes. Electron microscopy images show that the nanowires are smooth and slightly tapered. The diameters of the obtained nanowires are from?30 to 70?nm and their length is around 1?μm. X-ray diffraction analysis and transmission electron microscopy reveal that the nanowires have a zinc-blende structure throughout the whole range of obtained compositions, and have a [Formula: see text] growth axis. The Raman measurements reveal both the expected splitting and shift of phonon lines with increasing Mg content, thus proving the substitutional incorporation of Mg into metallic sites of the ZnTe lattice.     

Preparation and characterization of dendritic silver nanoparticles

Dendritic silver nanoparticles have been prepared by a soft solution technique from the aqueous solution of silver nitrate and poly (vinyl pyrrolidone) (PVP) in the presence of ethanol used as a reducing agent. The resultant silver nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive analyses of X-ray (EDX), and UV-Visible absorption spectroscopy. It was found that the well-defined dendritic silver nanoparticles which had the length 0.5–1 m and the width of 100–200 nm.     

From cobalt nitrate carbonate hydroxide hydrate nanowires to porous Co(3)O(4) nanorods for high performance lithium-ion battery electrodes

We have developed a simple approach for the large-scale synthesis of cobalt nitrate carbonate hydroxide hydrate (Co(CO(3))(0.35)(NO(3))(0.2)(OH)(1.1)·1.74H(2)O) nanowires via the hydrothermal process using sodium hydroxide and formaldehyde as mineralizers at 120?°C. The porous Co(3)O(4) nanorods 10-30?nm in diameter and hundreds of nanometres in length have been fabricated from the above-mentioned multicomponent nanowires by calcination at 400?°C. The morphology and structure of cobalt nitrate carbonate hydroxide hydrate nanowires and Co(3)O(4) nanorods have been characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and x-ray powder diffraction (XRD). Moreover, the porous Co(3)O(4) nanorods have been applied in the negative electrode materials for lithium ion batteries, which exhibit high electrochemical performance.     

Fabrication of single-crystalline gallium nitride nanowires by using alginate as template

Hexagonal gallium nitride nanowires were synthesized successfully by solvothermal method with alginate as template. The microstructure, morphologies and compositions of the as-prepared product were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray (EDX). Results suggested that the rod-like nanowires were hexagonal single-crystalline GaN growing along [001] direction. The photoluminescence spectra (PL) of the GaN revealed that the as-synthesized sample possesses excellent optical properties.