微波固相反应制备CdS纳米粒子

硫化镉是一种重要的半导体材料,在太阳能转化、非线形光学、光电子化学电池和光催化方面具有广泛的应用[1,2]。近十年以来,人们已经使用了许多的方法来制备纳米硫化镉[3~7]。由于微波能同时促进吸热反应和放热反应,对化学反应具有催化作用,可降低反应的温度,从而为化学反应创造     

甲烷氧化菌素介导一步法合成合成纳米银

以硝酸银为前体物,甲烷氧化菌素(Mb)将Ag(Ⅰ)还原Ag(0),并形成纳米银粒子(AgNPs),同时Mb吸附在形成的AgNPs表面,起到保护剂作用避免AgNPs聚集沉淀.采用紫外-可见光谱、荧光光谱、红外光谱、透射电镜和X射线电子能谱等对合成的AgNPs粒子过程、Mb合成AgNPs官能团、AgNPs形貌和AgNPs结构及价态等进行了分析.结果表明Mb可以一步法合成AgNPs离子.     

纳米银的电化学合成

纳米颗粒因具有量子尺寸效应、表面效应和宏观量子隧道效应等不同于晶态体材料和单个分子的固有特性 ,显示出体材料不具备的导电特性、光电特性、光催化能力及随粒径变化的吸收或发射光谱 ,已被用于各种发光与显示装置[1] .其制备的化学方法主要有溶胶 -凝胶法、微乳法、化学沉淀法和醇解法等 [2 ] .近年来 ,新发展出一种电化学合成纳米粒子的方法 ,如 Braun等 [3]利用 DNA模板电化学合成了银纳米线 ,Yu等[4 ] 用电化学合成了金纳米棒 ,Zhu等[5] 利用超声电化学合成了半导体 Pb Se纳米粒子 ,Amigo等 [6 ]用电化学方法合成了 Fe-Sr氧化…     

油酸囊泡层状液晶作为模板电化学合成银纳米颗粒

在油酸囊泡的层状液晶中利用电化学沉积法成功地制备了银纳米颗粒。并用扫描隧道显微镜(STM)和透射电子显微镜(TEM)对银纳米颗粒进行了表征，发现银纳米颗粒能够均匀地分散在油酸囊泡中，并且油酸囊泡能够有效地阻止产生的银纳米颗粒发生聚集反应。此外，我们还提出了银纳米颗粒形成的机理。     

Comparative Studies on the Quick Recognition of Melamine Using Unmodified Gold Nanoparticles and p‐Nitrobenzenesulfonic Grafted Silver Nanoparticles

Both unmodified gold nanoparticles (AuNPs) and p‐nitrobenzenesulfonic (p‐NBS) grafted silver nanoparticles (AgNPs) were prepared by chemical synthesis, respectively. They could be used for visual detection via the interaction with the twelve amide compounds including melamine. These color changes could be seen with the naked eye directly and monitored by ultraviolet visible (UV‐Vis) absorbance spectra. The recognition mechanism for both nanoparticles was comparatively investigated by the addition of glutathione (GSH) in the presence of melamine, respectively. The triple hydrogen bonding recognition and the attractive van der Waals interactions between melamine (0.5 mg/L) and AuNPs were responsible for the color change during its aggregation (red‐to‐purple or blue), whilst the electron donor‐acceptor interaction between melamine (0.2 mg/L) and p‐NBS modified on the surface of AgNPs resulted in the color changes (yellow‐to‐grey or dark green).     

In Situ Synthesis of Silver Nanoparticles for Ag‐NP/Cotton Nanocomposite and Its Bactericidal Effect

For years, nanotechnology has been considered as an important field that has opened new opportunities for extensive research. In biomedical applications, of all the metal nanoparticles, silver nanoparticles (Ag‐NPs) have played an important role because of their antibacterial properties. Ag‐NPs have been demonstrated to possess antibacterial properties in many applications. However, the minimum number of NPs required on the surface to prevent bacterial growth is yet to be determined. It is worthwhile studying the decrease of bacterial growth rate or the level of inhibition as a function of the size or density of NPs. Therefore, in this paper we discuss the size of the NPs that can stimulate the bactericidal property. It should also be noted that NPs larger than 100 nm might not be effective against bacteria. Moreover, this study employs polyvinyl pyrrolidone (PVP) and cellulose as reductants to form strong covalent bonds under UV light, which can help synthesize Ag‐NP/cotton nanocomposites. This type of nanocomposite displays high cell viability and improved antimicrobial activity. A fairly simple application involves the use of UV light to increase particle distribution and impart bactericidal property.     

One‐step Hydrothermal Synthesis and Assembly of Copper and Silver Nanoparticles to Aggregates in Glyoxal Reduction System

A simple hydrothermal process has been developed for the synthesis and assembly of copper and silver nanoparticles to aggregates. The reduction of Cu²⁺ and Ag⁺ ions to the zerovalent metal was performed by glyoxal in the absence of any external agent. The produced glyoxylic acid (GA) in the redox process stabi‐ lized metallic copper and silver particles and rendered them oxidation resistant for several months and dispersible in polar organic solvents and water. Detailed nanostructures of synthesized products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD). The results demonstrated that assembly of nanoparticles to aggregates and their regularity were dependent on the reaction conditions such as temperature and concentration of the starting material. The Ostwald ripening process was proposed to explain the formation of copper nanoparticles by TEM observation at several times during the reaction. The existence of the surface stabilizing agent was identified by Fourier Transform infrared spectroscopy (FT‐IR) and thermogravimetric analyses (TGA).     

Voltammetric Determination of Trace Amounts of 2‐Methyl‐4,6‐Dinitrophenol at a Silver Solid Amalgam Electrode

The voltammetric behavior of 2‐methyl‐4,6‐dinitrophenol was investigated by differential pulse voltammetry (DPV) at a nontoxic mercury meniscus‐modified silver solid amalgam electrode (m‐AgSAE). Conditions have been found for its determination by DPV at m‐AgSAE in the concentration range of 0.2 to 1 μmol L^?1.     

Lewis‐Base Stabilized N‐Silver(I) Succinimide Complexes: Synthesis,Crystal Structures and Their Use as CVD‐Precursors

Four Lewis‐base stabilized N‐silver(I) succinimide complexes of type [L_n·R_m·AgNC₄H₄O₂] (L = N,N,N′,N′‐tetramethylethylenediamine (TMEDA), n = 1, m = 0, 2a ; L = P(OEt)₃, n = 2, m = 0, 2b ; L = PPh₃, m = 0, n = 2, 2c ; L = P(OMe)₃, R = TMEDA, n = 1, m = 1, 2d ) were prepared by a “one‐pot” synthesis methodology and characterized. The molecular structures of 2a and 2c have been determined by using X‐ray single crystal analysis. Complex 2a exists as ion pair {[Ag(TMEDA)₂]⁺[Ag(NC₄H₄O₂)₂]^–} in the solid state and complex 2c is a monomer with the three‐coordinate silver atom. Complex 2b was used as precursor in the deposition of silver for the first time by using MOCVD technique. The silver films obtained were characterized using scanning electron microscopy (SEM) and energy‐dispersion X‐ray analysis (EDX). SEM and EDX studies show that the dense and homogeneous silver films could be obtained.     

Ion‐Exchange‐Assisted Synthesis of Pt‐VC Nanoparticles Loaded on Graphitized Carbon: A High‐Performance Nanocomposite Electrocatalyst for Oxygen‐Reduction Reactions

Carbide‐based electrocatalysts are superior to traditional carbon‐based electrocatalysts, such as the commercial Pt/C electrocatalysts, in terms of their mass activity and stability. Herein, we report a general approach for the preparation of a nanocomposite electrocatalyst of platinum and vanadium carbide nanoparticles that are loaded onto graphitized carbon. The nanocomposite, which was prepared in a localized and controlled fashion by using an ion‐exchange process, was an effective electrocatalyst for the oxygen‐reduction reaction (ORR). Both the stability and the durability of the Pt‐VC/GC nanocomposite catalyst could be enhanced compared with the state‐of‐the‐art Pt/C. This approach can be extended to the synthesis of other metal‐carbide‐based nanocatalysts. Moreover, this straightforward synthesis of high‐performance composite nanocatalysts can be scaled up to meet the requirements for mass production.     

Probing Surface Enhancement Effect of Molecules On/Between Silver Nanoparticles in Surface Enhanced Raman Scattering

To explore the mechanisms in Surface‐enhanced Raman Scattering (SERS) measurements, silver nanoparticles (AgNPs) were first prepared by a silver mirror reaction to form different particle sizes and different distributions on glass substrates. After the resulting surfaces were probed with molecules of p‐Amino‐thiophenol (pATP), p‐Nitrothiophenol (pNTP), and p‐Mercaptobenzoic acid (pMBA) individually, the substrates were placed into reaction solutions to grow additional AgNPs. In this way, probe molecules could be trapped between two nanoparticles, possibly having the so‐called “hot spot” effect. To examine the variations of morphologies of AgNPs in each of the steps, the substrates were examined by field‐emission scanning electron microscope (FE‐SEM). The morphologies also were correlated with the SERS signals. Two bands in the SERS spectra of probe molecules were selected as indications of the enhancements from electromagnetic (EM) effect and charge‐transfer (CT). Results indicate that the SERS signals from the EM effect were increased ca. 5 times after growing additional AgNPs on the molecule‐modified AgNPs substrates. The SERS signals from CT effect were increased two orders of magnitude after growing additional AgNPs. The increase of enhancement for molecules between AgNPs was caused mostly by CT effect. Based on the effect of particle size and distribution of the AgNPs, the EM effect was strongly influenced by the particle size of the AgNPs, while the CT effect was less sensitive to the variation of the morphologies of the AgNPs.     

纳米银在细菌纤维素凝胶膜中的原位合成及性能表征

在细菌纤维素纳米纤维网络结构中采用吐伦试剂与含醛基化合物原位反应生成纳米银颗粒, 制备了纳米银/细菌纤维素(n-Ag/BC)复合凝胶膜, 研究了不同反应条件对复合材料的银含量、 化学结构和晶体结构的影响以及n-Ag/BC的微观结构和纳米银在纤维素网络中的存在形态; 探讨了纳米银颗粒在纤维素网络中的形成机理; 采用伤口常见细菌之一金黄色葡萄球菌测试了n-Ag/BC的抑菌性能; 将n-Ag/BC与胎鼠表皮细胞共培养考察了材料的生物相容性. 研究结果表明, 在细菌纤维素纳米网络结构中可生成直径约为几十纳米的单质纳米银粒子; n-Ag/BC的银含量随着吐伦试剂浓度的增加而增加, 同时银含量还取决于含醛基化合物的用量; 原位反应生成纳米银粒子后细菌纤维素的晶型和结晶度没有发生变化; 纳米银颗粒在细菌纤维素纳米网络结构的交叉处生成, 复合材料n-Ag/BC对金黄色葡萄球菌的抑菌率达到99%以上, 不影响细胞的增殖和分化过程, 具有良好的生物相容性, 是一种有广阔应用前景的创伤修复抗感染材料.     

Interference‐Free Electrochemical Detection of Nanomolar Dopamine Using Doped Polypyrrole and Silver Nanoparticles

This paper presents a new approach to detect dopamine in nanomolar range using an electrochemical sensor utilizing a composite made of chitosan‐stabilized silver nanoparticles and p‐toluene sulfonic acid‐doped ultrathin polypyrrole film. Studies included cyclic voltammogram, amperometry, differential pulse voltammetry and also investigation by electrochemical impedance spectroscopy. A detection limit of 0.58 nM was achieved in the linear range 1×10^?9 M to 1.2×10^?7 M. High sensitivity towards DA, good reproducibility and long‐term stability have been demonstrated without interference from ascorbic acid, uric acid, epinephrine, L ‐dopa, glucose. The sensing system was successfully applied for quantitative determination of dopamine in commercially available human blood serum.     

Voltammetric Determination of N,N‐Dimethyl‐4‐amine‐carboxyazobenzene at a Silver Solid Amalgam Electrode

The voltammetric behavior of N,N‐dimethyl‐4‐amino‐2′‐carboxyazobenzene was investigated by differential pulse voltammetry (DPV) at a mercury meniscus‐modified silver solid amalgam electrode (m‐AgSAE). Conditions have been found for its determination by DPV at m‐AgSAE in the concentration range of 0.4 to 15 μmol L^?1.     

Ultrafast Preparation of AIE‐Active Fluorescent Organic Nanoparticles via a “One‐Pot” Microwave‐Assisted Kabachnik–Fields Reaction

The development of effective strategies for fabrication of fluorescent organic nanoparticles (FONs) with an aggregation‐induced emission (AIE) feature has an important impact on the biomedical applications of these AIE‐active FONs. In the current work, an ultrafast strategy for fabricating AIE‐active FONs is developed through a “one‐pot” microwave‐assisted, catalysts‐free, and solvent‐free Kabachnik–Fields (KF) reaction for the first time. It is demonstrated that such organophosphorous‐containing AIE‐active block polymers can be synthesized within 2 min under air atmosphere through the microwave‐assisted KF reaction. These polymers show amphiphilic properties and can self‐assemble into mPEG‐CHO‐Phe‐NH₂‐DEP FONs, which display high water dispersibility and desirable optical properties. Biological evaluation results suggest that the mPEG‐CHO‐Phe‐NH₂‐DEP FONs exhibit low toxicity and are potential for biological imaging applications. More importantly, many other multifunctional AIE‐active FONs can also be fabricated through the strategy described in this work owing to the universality of KF reaction. Besides, combined with the excellent properties of mPEG‐CHO‐Phe‐NH₂‐DEP FONs, it is believed that such microwave‐assisted KF reaction shall be an effective route for designing various AIE‐active nanomaterials for different biomedical applications.

     

Synthesis of Layered Sodium Manganese Phosphate via Low-heating Solid State Reaction and Its Properties

The layered nanocrystalline sodium manganese phosphate was synthesized by low‐heating solid state reaction using MnSO₄·H₂O and Na₃PO₄·12H₂O as raw materials. The resulting sodium manganese phosphate and its calcined products were characterized using element analysis, thermogravimetry and differential thermal analyses (TG/DTA), Fourier transform IR (FT‐IR), X‐ray powder diffraction (XRD), scanning electron microscopy (SEM), ultraviolet‐visible (UV‐Vis) absorption spectroscopy, and magnetic susceptibility. The results showed that the product obtained at 70°C for 3 h, NaMnPO₄·3H₂O, was a layered compound, and its crystallite size and interlayer distance were 27 nm and 1.124 nm, respectively. The thermal process of NaMnPO₄·3H₂O between room temperature and 700°C experienced three steps, the dehydration of the one adsorption water at first, and then dehydration of the two crystal waters, at last crystallization of NaMnPO₄. Magnetic susceptibility measurements of NaMnPO₄· 3H₂O from room temperature to 2.5 K point to ferrimagnetic ordering at T_N‐35 K.     

Co3O4纳米粒子的固相合成及磁性研究

以Co(NO3)2.6H2O和NaOH为原料,用固相法合成了Co3O4纳米微粒。用XRD和FT-IR研究了反应进程,证明Co3O4在焙烧阶段形成。用TEM观察了Co3O4纳米微粒的形貌,用磁天平测试了其磁性。结果表明,固相法可以制得平均粒径为22 nm的铁磁性Co3O4纳米微粒,属立方晶系,形状为多角形。400℃焙烧2 h所得纳米Co3O4的磁性强度为1.7922×10-2mT-1。