Au/Ag核-壳结构纳米粒子的制备及其SERS效应

随着大量有关表面增强拉曼散射 (SERS)的实验和理论研究的开展 ,金属纳米粒子作为一类重要的 SERS增强介质 ,已引起了人们浓厚的研究兴趣 [1] .而 Au和 Ag作为最常用的活性基底物质 ,更是研究的热点 [2 ,3 ] .最近 ,美国印第安那大学的 Nie等 [4 ] 在单个银纳米粒子上 ,观察到高达 1 0 14 ～ 1 0 15的SERS因子 .同时 ,他们的另外一项工作表明银纳米粒子的形状和大小对 SERS活性有很大影响 [5] .但是 ,由于 Ag溶胶制备的重复性较差 ,且粒度分布不均匀 ,通过控制银颗粒大小而调控 SERS活性是相当困难的[6] .与 Ag相比 ,Au在可见光…     

Fluorescent Property of Gold Nanoparticles with Different Surface Structures

"?Fluorescence spectra of naked gold nanoparticles, triphenylphosphine stabled gold nanoparticles, and 3-mercaptopropionic acid substituted gold nanoparticles were studied. It was found that fluorescence intensities of gold nanoparticles were highly sensitive to surface molecules. The fluorescence quenching effect of these gold nanoparticles on CdSe nanoparticles was also investigated. This quenching effect was related to the overlap degree between the absorption spectra of gold nanoparticles and the emission spectrum of CdSe nanoparticles, and was surface-dependent as well. "     

金纳米粒子与聚吡咯纳米管的复合及其SERS效应研究

通过柠檬酸盐与HAuCl4水溶液在微沸状态下反应制备的金纳米粒子因其特殊的表面与界面效应在光学、生物学和催化化学领域得到了广泛应用,而聚吡咯(PPy)具有环境稳定性好、电导率高且变化范围大、容易合成等优点,聚吡咯纳米管可用作导电材料、酶封装材料、抗静电材料,也可用于制备传感器、传动器、固体电解质电容器等。     

纳米金-蛋白A介导抗体定向固定的压电传感及电化学特性研究

以纳米金为载体标记蛋白A(PA),用于介导抗体在压电石英晶体金电极表面的定向固定化.以补体C_1q抗体为模型,采用压电传感技术实时监察了此敏感界面的免疫反应过程,并考察了与补体C_1q免疫反应的压电响应性能.金标PA固定抗体的方法与传统的直接PA固定化方法相比较,具有传感界面无需活化,固定抗体的免疫活性高等优点,可对相应抗原进行高灵敏的压电免疫检测.分别利用循环伏安和电化学交流阻抗技术对金标PA固定抗体及其免疫反应的动力学过程进行了表征.     

聚乙二醇光化学法制备金纳米微粒及共振散射光谱研究

采用共振散射光谱、紫外-可见吸收光谱、透射电镜对聚乙二醇(PEG)-Au3+纳米光化学反应进行了研究。讨论了金纳米粒子合成条件的影响,发现金纳米粒子的尺寸与PEG分子量大小有关。建立了一个利用不同分子量PEG制备一系列粒径为6～60 nm金纳米粒子的光化学合成新方法。根据PEG分子的空间位阻、疏水性等解释了PEG分子量不同而获得不同粒径金纳米粒子的原因。提出了一个合理的纳米光化学反应机理。     

钯纳米粒子在电极表面的制备及其对氧的催化还原

纳米微粒的体积效应使其成为表面纳米工程及功能化纳米结构材料制备的理想研究对象 [1～ 3] .纳米粒子具有独特的电子、催化及光学特性[4 ] ,近年来关于纳米粒子的制备及其在材料科学领域中的应用受到研究者的极大关注 .而贵金属纳米粒子由于其在催化领域中的广泛应用而成为最重要的研究对象之一[5,6 ] .电催化氧还原是一直为化学家瞩目的研究领域[7～ 9] .研究主要目的之一是寻找合适的氧电极反应催化剂 ,并使之能够应用于燃料电池中 .其中催化氧电极材料研究得最多的是贵金属 Pt[10 ,11] .贵金属 Pd对氧催化还原的研究工作很少 .我们首次…     

Change Color Effect and Spectral Properties of Gold Nanoparticle-cationic Surfactants System

The change color effect of gold nanoparticle solutions was studied by means of resonance scattering and absorption spectrometry and scan electron microscopy. The red Au nanoparticles with a size of 10 nm exhibit a resonance absorption peak and a resonance scattering peak all at 525 nm. After some inorganic electrolyte was added to a red Au nanoparticles solution, the color of the solution became blue and the absorbance at 600-700 nm was significantly increased. The ratio of the concentration of rnonovalent cations, at which the resonance scattering of the system at 525 nm is maximal to that of divalent cations, is in the range of 100 : 1--100 ; 1. 8. It is in good agreement with the Schulze-Hardy rule of the coagulation value of electrolyte. After adding some cationic surfactants to the above solution, the color of the solution is in deep blue, with two resonance absorption peaks at 550 and 680 nm, and a greatly enhanced resonance scattering peak at 525 nm. The experiments demonstrate that the stronger the hydrophobicity of the cationic surfactant is, the stronger the change color effect of the Au nanoparticle solution promoted by cationic surfactant is. The change color effect of Au nanoparticle solution is resulted from the increased diameter of Au nanoparticles, and the changes of resonance absorotion DeaR and resonance scattering.     

金纳米粒子在平整硅基表面上的组装

采用水相硅烷化方法,将３－氨基丙基－三甲氧基硅烷（ＡＰＳ）组装在湿化学法处理的单晶硅表面上。接触角、原子力显微镜（ＡＦＭ）、Ｘ射线光电子能谱（ＸＰＳ）表征结果显示得到了平整均匀的具有氨基表面的自组装膜。ＳＥＭ观察表明,１６ｎｍ的金纳米粒子可以在上述氨基表面上形成均匀的亚单层排布,得到了具有Ａｕ纳米粒子／ＡＰＳ／Ｓｉ形成的纳米复合结构,进一步的处理可以使金纳米粒子在表面上的排列由随机趋于有序化。     

Experimental and theoretical studies of reaction pathways of direct propylene epoxidation on model catalyst surfaces

The direct epoxidation of propylene to propylene oxide (PO) using molecular oxygen is an attractive alternative to current production methods using chlorohydrin or hydroperoxide-mediated processes, which are environmentally harmful and expensive. Although direct ethylene epoxidation using Ag-based catalysts has been practiced industrially for decades, due to the presence of allylic hydrogen in propylene the selectivity toward epoxide is generally much lower for propylene than for ethylene. Mechanistic understanding on well-characterized surfaces of model catalysts can potentially provide guidance to effectively alter the electronic properties of the catalyst in order to increase PO selectivity. This review summarizes both experimental and theoretical studies on model catalysts for propylene epoxidation and their contributions to elucidating the reaction mechanism, intermediates, and active sites. We first show examples of experimental studies on Cu, Ag, and Au surfaces, and compare the reaction pathways and intermediates on these surfaces. Novel approaches including plasmon-mediated catalysis and utilization of shape-controlled crystal facets that open new opportunities for improving PO selectivity will also be discussed. We then describe how density functional theory (DFT) calculations have provided important insights into the reaction mechanism and active sites on Cu, Ag, and Au surfaces and clusters. Propylene oxidation pathways on other relevant metal surfaces will also be discussed. The combined experimental and computational studies elucidate the nature of surface oxygen species and the role of the oxametallacycle intermediate. We conclude by highlighting design principles and insights for guiding further development of active and selective propylene epoxidation catalysts.     

Intense laser induced shock generation in gold targets

Abstract

Experiments carried out demonstrate the production due tosoft X-rays of enhanced ablation pressure. The targets used were planar gold foils. Aluminium targets were also used to demonstrate the relative effect.