Production of nanoparticles of copper compounds by anodic dissolution of copper in organic solvents

The anodic behaviour of copper was investigated in ethanol solution containing LiClO₄, LiCl electrolyte and water. The type of electrolyte and the water content influences the mechanism of the anodic process and the formation of anodic products. In LiClO₄ electrolyte the dissolution of copper is related to the oxidation of Cu(I) to Cu(II). In solutions of LiCl the etching of copper begins with the creation of soluble complexes of Cu(I) with chloride ions and solvent molecules. At potentials above 0.4 V the formation of alkoxides was observed in both solutions, characterized by a yellow tint. On the other hand, above 0.8 V (i.e. above the equilibrium potential of alcohol oxidation) copper dissolution is accompanied by the formation of a blue colloidal suspension of Cu (II) copper salt. Anodic etching of copper in solutions containing 3% H₂O at potentials higher than 0.4 V leads to the formation of colloidal suspension of copper oxide nanoparticles.     

导电高分子PEDOT／PSS保护银纳米颗粒的制备与表征

利用导电高分子聚（3，4-二氧乙基噻吩）／聚（对苯乙烯磺酸）（PEDOT／PSS）作保护剂，制备了银纳米颗粒，用UV-Vis和TEM对其进行了表征．结果表明，选择合适量的PEDOT／PSS保护剂可以得到大小分布较窄银纳米颗粒．     

(Ag)_核·(Au)_壳复合纳米粒子的制备

以银原子团簇作晶种,采用微波高压液相合成法制备了分散性好、规则球形的(Ag)核·(Au)壳复合纳米粒子。研究了(Ag)核·(Au)壳复合纳米粒子的紫外可见吸收光谱和共振散射光谱特性。结果表明,液相(Ag)核·(Au)壳复合纳米粒子和高压微波合成的液相金纳米粒子的最强共振散射峰均在580nm处,它们的吸收光谱图相似,最大吸收分别在518.5nm和524.8nm。     

Preparation of methanol oxidation electrocatalysts: ruthenium deposition on carbon-supported platinum nanoparticles

Methanol oxidation electrocatalysts were prepared from Ru electrochemical or spontaneous deposition on commercial-grade carbon-supported Pt nanoparticles (Pt-Vulcan XC72, E-TEK). The resulting Ru coverage was estimated by cyclic voltammetry in supporting electrolyte. The maximum electrocatalytic activity for methanol oxidation at room temperature was observed at lower Ru coverage for spontaneous deposition than for electrodeposition; _Ru 10% vs 20%, respectively. On the other hand, higher current densities for methanol oxidation were obtained in the case of electrodeposited Ru. These two results were related to the presence of non-reducible ruthenium oxides in the spontaneous deposit. The present work provides evidence that (i) efficient DMFC electrocatalysts can be achieved by Ru deposition on Pt nanoparticles, and (ii) formation of a PtRu alloy is not a required condition for effective methanol electrooxidation.     

Structural characteristics of oxide nanosphere supported metal nanoparticles

Structural characterization by transmission electron microscopy of metal nanoparticle coatings on oxide nanospheres has been employed to point out the potential of such materials for use as porous support model catalysts. On silica and titania nanospheres of various origins surface-mediated metal deposition at mild temperature conditions has been utilized to fabricate Pt, Pd, Ag, and Au nanoparticle coatings on the oxide supports. Promising coating characteristics have been achieved for Ag and Au nanoparticles by direct reduction on terminating hydroxyl-rich St?ber silica. A high-resolution electron microscopy analysis directed to surface stress, lattice contraction and planar lattice defects of the latter particles revealed no strong metal-support interaction.     

Morphology and activity of nanosized NdCl3 catalyst for 1,3‐butadiene polymerization

The binary lanthanide catalyst for 1,3‐butadiene was invented for 40 years ago. However, it has not been employed in commercial application due to its poor solubility and low activity. Nanosized neodymium chloride (NdCl₃) was prepared in tetrahydrofuran (THF) medium through dissolution, chelation, and colloidal formation steps. Anhydrous NdCl₃ was dissolved in THF, and ca. 1.5 THF molecules were coordinated. In the colloidal formation step, THF was slowly replaced with the addition of cyclohexane, and pale blue nuclei, nanosize below 200 nm, were formed. The structural studies for NdCl₃ · xTHF using X‐ray powder diffraction (XRD) and scanning electron microscope (SEM) indicate that high ordered crystallinity is decreased with reduced particle size from trigonal prismatic to porous sphere structure. Nano NdCl₃, obtained as colloidal state in cyclohexane, was activated with Al(iBu)₃ and Al(iBu)₂H at room temperature and employed for 1,3‐butadiene solution polymerization. The nanosized Nd catalysts showed high activity (1.0 ～ 1.3 × 10⁵ g/Nd mol · h), which is comparable to that of the ternary neodymium catalyst Nd(neodecanoate)₃/AlEt₂Cl/Al(iBu)₃. The microstructures of polybutadiene, cis, trans, and vinyl, are about 96.0, 3.5, and 0.5%, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1279–1283, 2005     

The flexible surface or the rigid surface?

In this paper we discuss aspects of the concept described by Somorjai as the flexible surface, and whether some surfaces can be considered to be inflexible, or rigid. We present STM results which appear to manifest both types of behaviour for surfaces, depending on their oxidation state. Copper metal surfaces can be classed as flexible, showing facile reconstruction in the presence of oxygen, whereas an oxidised Pd(110) surface shows no apparent diffusivity, even at 500 K. We go on to show data for a bulk oxide which indicates that sub-stoichiometry in the sample induces an element of flexibility in the surface, especially during reaction with oxygen. Finally, this is related to the direct observation of spillover on model catalysts of Pd nanoparticles supported on TiO₂. It must be recognised that flexibility relates to surface diffusivity and hence length- and time-scales. Surfaces which appear inflexible at short times may be flexible at long times. In relation to catalysis then, surface flexibility depends on the relationship between the time-scale of diffusive events on the surface and the catalytic turnover number.     

利用SPR生物传感器检测缺血修饰白蛋白

缺血修饰白蛋白(IMA)的检测对心肌缺血的早期诊断和治疗具有重要意义。利用纳米金颗粒和混合巯基自组装于金膜表面上,研制了一种快速检测IMA的表面等离子体共振(SPR)生物传感器。同时比较了直接法和抑制法的检测下限。结果表明:直接检测法可以检测到393ng/L的IMA,而抑制检测法检测限小于5.0 ng/L。与现有的IMA检测方法相比,SPR生物传感器具有特异性好、检测下限低以及检测耗时短等优点。     

基于表面等离子体共振传感器的尿微量白蛋白检测

检测尿微量白蛋白(MAU)可对轻微肾脏损害进行早期诊断,也可对高血压患者可能发生的心脑血管事件进行预测。实验将抗体通过巯基自组装固定于Au膜表面,研制了一种快速检测MAU的表面等离子体共振(SPR)生物传感器。结果表明:直接检测法可以检测到0.3μg/L的MAU,而纳米Au放大法检测限可以低至0.03μg/L。     

Preparation and characterization of TiO2 and polymer nanocomposite films with high refractive index

Novel nanocomposite films of TiO₂ nanoparticles and hydrophobic polymers having polar groups, poly (bisphenol‐A and epichlorohydrin) or copolymer of styrene and maleic anhydride, with high refractive indices, high transparency, no color, solvent‐resistance, good thermal stability, and mechanical properties were prepared by incorporating surface‐modified TiO₂ nanoparticles into polymer matrices. In the process of preparing colloidal solution of TiO₂ nanoparticles, severe aggregation of particles can be reduced by surface modification using carboxylic acids and long‐chain alkyl amines. These TiO₂ nanoparticles dispersed in solvents were found not to aggregate after mixing with polymer solutions. Transparent colorless free‐standing films were obtained by drying a mixture of TiO₂ nanoparticles colloidal solution and polymer solutions in vacuum. Transmission electronic microscopic studies of the films suggest that the TiO₂ nanoparticles of 3–6 nm in diameter were dispersed in polymer matrices while maintaining their original size. Thermogravimetric analysis results indicate that the nanocomposite film has good thermal stability and the weight fraction of observed TiO₂ nanoparticles in the film is in good accordance with that of theoretical calculations. The refractive index of nanocomposite films of TiO₂ and poly(bisphenol‐A and epichlorohydrin) was in the range of 1.58–1.81 at 589 nm, which linearly increased with the content of TiO₂ nanoparticles from 0 to 80 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007