电感耦合等离子体原子发射光谱（ICP-AES）法测定高镍铜液体样品中金、钯、铂

为实现中控液体物料中金、钯、铂元素的精准定量分析,为工艺生产定向富集和高效提取提供数据支持,本文建立了ICP—AES法测定中控冶炼系统中高镍铜液体样品中金、铂和钯3种元素含量的测定方法。确定了试液用碲共沉淀,贵金属进入滤渣,经火试金分离富集得到贵金属合粒,合粒经王水溶解后,于王水介质中在电感耦合等离子光谱仪上同时测定金钯铂的量。该方法金、铂、钯的测定范围为 0.014mg/L～5mg/L,回收率为92.2%～104.4%, RSD为3.21%～10.58%,方法满足高镍、铜液体样品中金、钯、铂元素的测定。     

Ultrafast laser studies of the photothermal properties of gold nanocages

Au nanocages were synthesized via a galvanic replacement reaction. The extinction peak of these hollow structured particles is shifted into the near-IR compared with the Ag nanocube templates. Energy transfer from the Au nanocages into the surrounding environment (water) as well as the coherently excited vibrational modes of the nanocages were studied by femtosecond pump-probe spectroscopy. The time scale for energy relaxation was found to increase with the size of the particles, with the relaxation time being independent of the laser intensity. The time scales for relaxation are comparable to those for solid spherical gold particles and are consistent with energy relaxation being controlled by heat dissipation in the solvent. The period of the coherently excited vibrational mode is proportional to the dimensions of the nanocages. Intensity-dependent measurements show that in solution the nanocages maintain their integrity up to lattice temperatures of 1100 +/- 100 K.     

Flame atomic absorption spectrometric determination of trace amounts of palladium,gold and nickel after cloud point extraction

In this article, a sensitive cloud point extraction procedure for the preconcentration of trace amounts of palladium, gold and nickel prior to their determination by flame atomic absorption spectrometry has been developed. The cloud point extraction method is based on the complexation of Pd(II), Au(II), and Ni(II) ions with 1-(2-pyridylazo)-2-naphthol and entrapping in non-ionic surfactant Triton X-114. The main factors affecting cloud point extraction efficiency, such as pH of sample solution, concentration of 1-(2-pyridylazo)-2-naphthol and Triton X-114, equilibration temperature and time, were investigated in detail. Under the optimized conditions, calibration curves were constructed for the determination of palladium, gold and nickel according to the general procedure. Linearity was maintained from 0.01 to 1.0 μg/mL for palladium, 10.0 μg/mL to 1.5 μg/mL for gold, and 10.0 μg/mL to 0.5 μg/mL for nickel. Detection limits based on three times the standard deviation of the blank divided by the slope of analytical curve (3Sb/m) for Pd(II), Au(III), and Ni(11) ions were 3.4, 3.9, and 2.4 μg/mL, respectively. Seven replicate determination of a mixture of 0.5 μg/mL palladium and gold and 0.2 μg/mL nickel gave a mean absorbance of 0.174, 0.150, and 0.201 with relative standard deviation ±1.5, ±1.3, and ±1.8%, respectively. The high efficiency of cloud point extraction to carry out the determination of analytes in complex matrices was demonstrated. The proposed method has been applied for determination of trace amount of palladium, gold and nickel in certified reference material and water samples with satisfactory results.     

Halo-carbonyl complexes of palladium,platinum and gold

In this review we summarize some recent literature data concerning synthetic procedures, properties, structure, reactivity and applications of halo-carbonyl complexes of palladium, platinum and gold, taking into consideration that the organometallic chemistry of these metals, with a particular attention to the halo-carbonyls, has been reviewed 20 years ago [F. Calderazzo, J. Organomet. Chem. 400 (1990) 303]. A brief overview of the early studies is provided.     

Dithizonates of gold and palladium

Contrary to some previous reports, it has been found that gold reacts with dithizone in the ratio 1:1 forming a red-brown complex, and in the ratio 2:1 forming a yellow complex, both extractable into chloroform. The proportion of these two complexes in the organic extract depends critically on several factors. Therefore, the use of dithizone as a spectrophotometric reagent and especially as an extractive titrant for gold cannot be recommended. Previous reports on the composition and colour of the dithizonates of palladium are confirmed, except that PdDz is soluble in carbon tetrachloride and in chloroform.     

Pincer-like amido complexes of platinum, palladium, and nickel

The ligands bis(8-quinolinyl)amine (BQAH, 1), (2-pyridin-2-yl-ethyl)-(8-quinolinyl)amine (2-pyridin-2-yl-ethyl-QAH, 2), o-dimethylaminophenyl(8-quinolinyl)amine (o-(NMe2)Ph-QAH, 3), and 3,5-dimethylphenyl(8-quinolinyl)amine (3,5-Me2Ph-QAH, 4) have been prepared in high yield from aryl halide and amine precursors by palladium-catalyzed coupling reactions. Deprotonation of 1 with nBuLi in toluene affords the lithium amide complex [Li][BQA] (5), whose dimeric solid-state crystal structure is presented. Lithium amide 5 was transmetalated by TlOTf to afford the thallium(I) amido complex [Tl][BQA] (6). An X-ray structural study of 6 shows it to be a 1:1 complex of the BQA ligand and Tl. Entry into the group 10 chemistry of the parent ligand 1 was effected by both protolytic and metathetical strategies. Thus, the divalent chloride complexes (BQA)PtCl (7), (BQA)PdCl (8), and (BQA)NiCl (9) were prepared and fully characterized. An X-ray structural study for each of these three complexes shows them to be well-defined, square-planar complexes in which the auxiliary BQA ligand binds in a planar, eta(3)-fashion. For comparison, the reactivity of ligands 2-4 with (COD)PtCl2 was studied. While reaction with ligand 2 afforded an ill-defined product mixture, ligands 3 and 4 reacted with (COD)PtCl2 to generate the unusual alkyl complexes (o-(NMe2)Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (10) and (3,5-Me2Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (11), both of which have been structurally characterized.     

pH-triggered assembly of gold nanorods

The self-assembly of surfactant-protected gold nanorods (aspect ratio 3.3 +/- 0.3, 20.6 +/- 5.5 nm width, and 67.5 +/- 9.0 nm length) into ordered structures using adipic acid is presented. As made, the gold nanorods are coated with cationic surfactant, which gives them a net positive charge in aqueous solution. The pH-dependent assembly is directed by electrostatic interactions between the positively charged nanorods and negatively charged, deprotonated adipic acid. Absorption spectra and light scattering measurements of these nanorods suggest that aggregation is initiated in solution in the presence of adipic acid at pH 7-8, but not at pH 3, to form small assemblies of nanorods. Zeta potential measurements show that the assembly is significantly less positively charged in the presence of deprotonated adipic acid than when adipic acid is fully protonated.     

Photochemical synthesis of gold nanorods

Gold nanorods have been synthesized by photochemically reducing gold ions within a micellar solution. The aspect ratio of the rods can be controlled with the addition of silver ions. This process reported here is highly promising for producing uniform nanorods, and more importantly it will be useful in resolving the growth mechanism of anisotropic metal nanoparticles due to its simplicity and the relatively slow growth rate of the nanorods.     

Structure of supported palladium,silver and gold clusters

Clusters nucleated by inert gas aggregation have been studied by HREM. The clusters were supported by amorphous carbon films and by crystalline graphite fibres. Multiply twinned particles with 5-fold axes of symmetry were observed whose structures and orientations are discussed. It is also demonstrated that crystalline graphite substrates can be used to calibrate lattice distances and to improve the image processing. With the help of computer simulations complex structures were resolved.     

Ultrafast spectroscopy and coherent acoustic phonons of Au-Ag core-shell nanorods

We performed the first investigations of coherent acoustic phonons in Au-Ag core-shell nanorods, which were compared with the results of parental Au nanorods. Both breathing and extensional modes were observed in Au-Ag core-shell nanorods with ~11 nm Ag shell while only extensional modes were detected in other core-shell nanorods with 4-7 nm Ag shell. Young's modulus estimated from the oscillation period of extensional modes was found to be larger for Au-Ag core-shell nanorods with ~4 nm Ag shell, as compared with that of Au nanorods. The value of Young's modulus decreases with the increase of the Ag shell thickness and finally becomes smaller than that of Au nanorods. This phenomenon is interpreted in terms of the surface effects and the existence of grain boundaries in the lattice structure of Ag shell.     

Synthesis and mechanistic study of palladium nanobars and nanorods

This paper describes a simple and versatile method for growing highly anisotropic nanostructures of Pd, single-crystal nanobars bounded by {100} facets and single-crystal nanorods with their side surfaces enclosed by {100} and {110} facets. According to thermodynamic arguments, Pd atoms should nucleate and grow in a solution phase to form cuboctahedrons of spherical shape with their surfaces bounded by a mix of {111} and {100} facets. Anisotropic nanostructures can only form under kinetically controlled conditions, while the cubic symmetry is broken. In the present system, we found that one-dimensional growth could be induced and maintained through an interplay of the following processes: (i) speedy reduction of the precursor to ensure prompt addition of atoms to the seed; (ii) chemisorption of bromide on the seed to promote the formation of {100} and {110} facets; and (iii) localized oxidative etching on one specific face of the seed to initiate preferential growth on this face. Experimentally, the anisotropic growth can be achieved by varying the type and concentration of reducing agent, as well as by adjusting the reaction temperature. This methodology developed for Pd has also been extended to both Au and Pt. As expected for a kinetically controlled product, the anisotropic nanostructure evolved into the thermodynamically favored shape during an aging process.     

Organo-soluble chiral thiol-monolayer-protected gold nanorods

Here, we report the synthesis and characterization of organo-soluble chiral thiol-monolayer-protected gold nanorods. The resulting gold nanorods respectively covered with two opposite enantiomers via the strong covalent Au-S linkage were found to not only be stable in both organic media and solid state, but also show optical activity. Their circular dichroism (CD) spectra exhibited a mirror image relationship, indicating that enantiomeric thiol surfactant on gold surface can produce the corresponding enantiomeric gold nanorods. The densely packed azobenzene thiol monolayer on gold surface exhibited a photoresponsive behavior upon irradiation with 254 nm light instead of 365 nm light, which was found to have an effect on plasmonic absorption of gold nanorods.     

Fabrication and self-assembly of hydrophobic gold nanorods

Hydrophobic gold nanorods were fabricated from hydrophilic gold nanorods coated with hexadecyltrimethylammonium bromide by treating with mercaptopropyltrimethoxysilane (MPS) and subsequently octadecyltrimethoxysilane (ODS). The fabrication of the hydrophobic shell went through the process of (1) binding MPS onto the nanorods, (2) hydrolysis of methoxysilanes, and (3) immobilization of ODS by dehydration condensation. The 2- or 3-D ordered structures of hydrophobic nanorods were self-assembled by the evaporation of solvent on a substrate. The aspects of 2-D assemblies were dependent on the concentration of the nanorods, as was seen in transmission electron microscopic images. At a low concentration, the nanorods assembled parallel to the substrate, whereas they stood on the substrate at a high concentration. On the other hand, in a solid of the gold nanorods, the formation of the 3-D assembly was confirmed by small-angle X-ray scattering. The assembly consisted of hexagonal arrays of the gold nanorods and their lamellar accumulation.     

High-temperature seedless synthesis of gold nanorods

We demonstrate seedless synthesis of gold nanorods at high temperatures up to 97 degrees C. Using the correct silver nitrate concentration is crucial for formation of rod-shaped particles at all temperatures. We observed a decrease of nanorod length with increasing temperature, while the width stays constant throughout the temperature range. From kinetics studies, we show 3 orders of magnitude increase in nanorod growth rate when the temperature is raised from room temperature to 97 degrees C. From the temperature dependence of the growth rate, we obtain a average activation energy for growth on all facets of 90 +/- 10 kJ mol(-1). High-temperature synthesis of gold nanorods presents a more attractive method for scalable flow-based production of gold nanorods.     

Phase-controlled synthesis and characterization of nickel sulfides nanorods

Different one-dimensional nickel sulfides, NiS nanorods and Ni₉S₈ nanorods were synthesized in the presence (Route 1) and absence (Route 2) of gas CO₂. X-ray powder diffraction patterns, scanning electron microscopy and transmission electron microscopy images show that the product from Route 1 is NiS nanorods with a diameter of about 50-120 nm, while the product from Route 2 is Ni₉S₈ nanords about 70-200 nm in diameter. A molecular-template-like mechanism was proposed for the one-dimensional structures growth. The products were also investigated by Raman and photoluminescence (PL) spectroscopy.     

Excitation wavelength and fluence dependent femtosecond transient absorption studies on electron dynamics of gold nanorods

The electron dynamics of gold nanorods were systematically studied by using femtosecond transient absorption experiments. Two different excitation wavelengths (400 and 800 nm) have been used as the excitation sources to selectively excite transverse and longitudinal modes. The transient absorption spectra were found to be strongly dependent on the excitation wavelength and fluence. Laser pulses of 800 nm excite the longitudinal mode directly, which cause an increase in the electronic temperatures and subsequent broadening and bleaching of both the longitudinal and transverse modes. Pulses of 400 nm excite both the transverse and longitudinal modes simultaneously. At low excitation fluences, the energy is distributed into two modes according to their steady state extinction coefficients, under which the transient spectra are similar to those under excitation at 800 nm. However, as the excitation fluence exceeds a threshold, the bleaching of the longitudinal plasmon band saturates and the input energies mainly flow to the transverse mode. As a result, the bleaching of the transverse mode increases rapidly. The electron-phonon dynamics show a strong correlation with the bleaching amplitude. We have tried to explain the results with a consistent picture: the bleaching amplitude and electron-phonon relaxation time are directly related to energy distribution into different modes, which are excitation wavelength and fluence dependent. Our studies help to clarify the seemingly inconsistent results in the previous studies by different research groups.     

Crystal overgrowth on gold nanorods: tuning the shape, facet, aspect ratio, and composition of the nanorods

Electrochemically prepared Au nanorods were used as seeds for the overgrowth of thin shells of gold, silver, and palladium by using a mild reducing agent, ascorbic acid, in the presence of surfactants at ambient condition. The unique crystal facets of the starting nanorods results in anisotropic crystal overgrowth. The overgrowth rates along different crystallographical directions can be further regulated by adding foreign ions or by using different metal reduction methods. This overgrowth study provides insights on how different metal ions could be reduced preferentially on different Au nanorod surfaces, so that the composition, aspect ratio, shape, and facet of the resulting nanostructures can be rationally tuned. These surfactant-stabilized bimetallic Au(core)M(shell) (M=Au, Ag, Pd) nanorod colloids might serve as better substrates in surface-enhanced Raman spectroscopy as well as exhibiting enhanced catalytic properties.     

金纳米棒自组装的研究进展

金纳米棒具有独特的光电性能,其自组装形成的功能组装体能够展现出更加优异的整体协同性能,在纳米材料科学和生物医学领域中有广泛而重要的应用前景.本文从诱导自组装各种驱动作用力的角度,综述了金纳米棒自组装的最新研究进展,具体内容包括:表面张力引发的自组装、化学作用驱动如静电作用或氢键作用等引发的自组装以及生物分子识别作用引发的自组装.     

Controlling the length and shape of gold nanorods

In this paper, we report a new approach to fabricate gold nanowires by controlling the volume of the growth solution. The shape evolutions ranging from fusiform nanoparticles to 1-D rods were observed. Increasing the addition of the growth solution can control the length of nanorods. The length of the rods can be extended to 2 microm, and nanorods with aspect ratios of up to approximately 70 could be obtained.     

Separations involving palladium: Separation of lead,bismuth, cadmium,thallium, copper,cobalt and nickel from palladium

It has been shown that 1% dimethylglyoxime solution in alcohol can be efficiently used to separate quantitatively palladium from other metals of the copper group, as indicated in the new and more comprehensive scheme of qualitative analysis.