帽状锑纳米粒子的制备及表面等离子共振特性的研究

采用热蒸发法在SiO₂自组装单层膜上制备了帽状锑纳米粒子,通过扫描电镜(SEM)、原子力显微镜(AFM)、X射线衍射仪(XRD)和紫外-可见-近红外(UV-Vis-NIR)分光光度计对帽状复合纳米粒子的表面形貌、结构以及表面等离子共振特性进行了研究和表征。结果表明,制备的复合纳米粒子呈帽状,表面等离子共振峰具有明显的可调谐性,当二氧化硅粒径增大或锑帽层厚度增加时,等离子共振吸收峰位置红移。     

对称性降低的SiO2/Ag核壳结构纳米粒子的制备及表面增强拉曼活性研究

采用湿化学还原法在自组装的单层阵列二氧化硅纳米粒子表面沉积银膜制备了SiO2核/Ag帽复合纳米结构。通过透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)和紫外-可见分光光度计(UV/Vis)研究和表征了该复合纳米结构的表面形貌、结构及光学性质。所制备的复合纳米粒子表面粗糙,其表面呈现无数纳米级谷粒状结构,SiO2内核粒径为350nm的银纳米帽的表面等离子共振吸收的2个共振峰分别位于382和689nm处。以亚甲基蓝作为探测分子研究了SiO2粒径为350和450nm的SiO2/Ag帽状复合纳米粒子的表面增强拉曼散射(SERS)活性,增强因子分别为3.6×109和3.9×109。结果表明,湿化学还原法制备的SiO2核/Ag帽复合纳米结构是很好的拉曼活性基底。     

帽状锌纳米结构的制备及其表面等离子体共振特性

利用真空热蒸发法在二氧化硅纳米粒子单层膜上沉积锌薄膜制备了帽状锌纳米结构. 采用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)和紫外-可见吸收光谱(UV-Vis)对样品的形貌、结构和光学特性进行了表征和研究. SEM照片表明所得到的复合纳米粒子为不完全包裹的帽状结构, 且其表面较粗糙. XRD分析结果显示在二氧化硅纳米粒子上沉积的锌膜呈多晶六角密堆结构. 吸收光谱研究表明, 帽状锌纳米结构在570～760 nm范围内具有明显的由纵向双极子表面等离子体共振引起的吸收峰, 且随着锌帽层厚度的增加或二氧化硅内核粒径的增大, 该吸收峰逐渐红移; 当内核粒径增大到500 nm时, 帽状锌纳米结构在412 nm附近还出现了一个四极子共振峰.     

帽状银纳米粒子的制备及表面增强拉曼活性研究

采用真空热蒸发法在自组装的单层阵列二氧化硅纳米粒子表面沉积银膜制备了帽状银纳米粒子。通过透射电镜(TEM)、扫描电镜(SEM)和紫外-可见-近红外分光光度计 (UV-Vis-NIR)对其表面形貌及光学性质进行了表征。以吡啶-(2-偶氮-4)间苯二酚作为探针分子，研究了该复合纳米粒子的表面增强拉曼散射 (SERS) 活性，增强因子高达2.88×10⁶。结果表明在二氧化硅纳米粒子表面制备的帽状银纳米粒子是很好的表面增强拉曼散射活性基底。     

帽状铜纳米粒子的制备及表面增强拉曼散射活性研究

采用真空热蒸发法在SiO₂纳米粒子自组装单层膜上沉积铜薄膜制备了帽状铜纳米粒子。用扫描电镜、原子力显微镜和紫外-可见-近红外分光光度计对帽状复合纳米粒子的表面形貌和光学性质进行了表征。以亚甲基蓝和吡啶-(2-偶氮-4)间苯二酚为探针分子,研究了该复合纳米粒子的表面增强拉曼散射(SERS)活性。通过比较吸附在不同基底上的吡啶-(2-偶氮-4)间苯二酚的谱峰强度,探讨了SERS效应与表面等离子体共振(SPR)的关系。     

帽状金纳米结构的制备、表征及表面增强拉曼散射活性

采用真空离子溅射法在自组装的单层阵列二氧化硅纳米粒子表面沉积金薄膜, 制备了以SiO₂为核的帽状金纳米结构. 用透射电镜、扫描电镜、原子力显微镜、X 射线衍射仪和紫外-可见-近红外分光光度计对样品的表面形貌、结构及光学性质进行了表征. 以亚甲基蓝作为探针分子, 对金纳米帽的表面增强拉曼散射活性进行了研究, 结果显示, 吸附在金纳米帽上的分子拉曼散射信号得到显著增强, 增强因子达到10⁷数量级. 该基底在超灵敏生物和化学检测方面具有潜在的应用前景.     

非晶SiO2纳米灯笼的制备和表征

在1000 ℃用活性炭把二氧化锡粉末还原成单质锡, 锡作为催化剂, 硅片作为硅源同时作为收集衬底, 在硅片上制备出了非晶SiO2纳米灯笼. 灯笼的一端连在硅片上, 另一端为一个锡球, 中间是一些圆弧状的SiO2纳米线把两端相连. 纳米灯笼具有良好的对称性. 利用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED) 和HRTEM自带的能谱分析仪(EDS)对样品的表面形貌、微观结构和成分进行了分析研究. 结果表明, 灯笼中SiO2纳米线为非晶态, 结点是晶态锡, 结点表面覆盖一层非晶态的硅的氧化物. 结合实验条件对纳米灯笼的生长机理进行了讨论, 提出了纳米灯笼生长的一个模型.     

二维纳米金单层膜的构建及其生物电化学应用

利用Langmuir-Blodgett (LB)技术在氧化铟锡(ITO)电极上制备了二维纳米金(nano-Au)单层膜,采用扫描电子显微镜表征了二维纳米金单层膜.实验结果表明:表面压为28 mN/m时,可获得分散性好、形状规则且分布均匀的二维球形纳米金单层膜.利用LB技术制备了肌红蛋白(Mb)薄膜,并将其固定在二维纳米金单层膜修饰的电极表面,研究了肌红蛋白LB膜的直接电化学行为.结果表明:纳米金粒子能够有效地加速肌红蛋白的电子转移,其电子转移速率为1.415 s-1.     

帽状铝纳米粒子的制备及表面等离子共振特性

金属纳米材料具有许多独特的物理和化学性质,其中一个重要的光学性质就是表面等离子共振,然而在大多数情况下,金属纳米粒子表面等离子共振所产生的吸收峰被限制在相对狭小的范围内,很难进行调谐。近年来,以电介质为核金属为壳的核壳结构复合纳米材料成功的解决了这一问题,通过设计和剪裁内核的直径与外壳层厚度的比值,可以实现光学性质可调的特性[1～5]。此类复合材料可被广泛应用于光催化、传感器、光信息存储、生物光子学、生物医学等领域[6～11]。美国莱斯大学及德州的研究人员利用这类核壳结构纳米材料成功地实现了对体外乳腺肿瘤的杀灭实验[12]。在这种类型的材料中,对称性降低的即不完全包裹的纳米粒子如杯状[13]、帽状[13,14]、半球壳状[15]、月牙状[16]等核壳结构复合粒子由     

纳米岛状银膜@金纳米针尖表面增强拉曼散射传感界面及多巴胺分子的传感分析

多巴胺缺乏是导致帕金森疾病临床症状的主要原因.为有效检测分析多巴胺分子,本文通过磁控溅射技术制备了一种具有纳米岛状结构的银薄膜,使用无机碱性双氧水作为清洁还原剂,还原制备了一种毛胆状多纳米针尖的金纳米结构,并将纳米岛状结构的银薄膜和毛胆状多纳米针尖的金纳米结构作为表面增强拉曼散射(SERS)基底.通过银膜承载多巴胺分子...     

Fine-tuning of catalytic tin nanoparticles by the reverse micelle method for direct deposition of silicon nanowires by a plasma-enhanced chemical vapour technique

The reverse micelle method was used for the reduction of a tin (Sn) salt solution to produce metallic Sn nanoparticles ranging from 85 nm to 140 nm in diameter. The reverse micellar system used in this process was hexane-butanol-cetyl trimethylammonium bromide (CTAB). The diameters of the Sn nanoparticles were proportional to the concentration of the aqueous Sn salt solution. Thus, the size of the Sn nanoparticles can easily be controlled, enabling a simple, reproducible mechanism for the growth of silicon nanowires (SiNWs) using plasma-enhanced chemical vapour deposition (PECVD). Both the Sn nanoparticles and silicon nanowires were characterised using field-emission scanning electron microscopy (FE-SEM). Further characterisations of the SiNW's were made using transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. In addition, dynamic light scattering (DLS) was used to investigate particle size distributions. This procedure demonstrates an economical route for manufacturing reproducible silicon nanowires using fine-tuned Sn nanoparticles for possible solar cell applications.     

Effects of Cr2O3 modification on the performance of SnO2 electrodes in DSSCs

In this paper, we demonstrate that Cr(2)O(3), a visible absorbing insulator, can be used as an efficient blocking layer material for the anode of dye-sensitized solar cells (DSSCs). We prepared SnO(2) electrodes surface-modified with Cr(2)O(3) with various Cr/Sn ratios and studied the effect of the modification on the performance of DSSCs. DSSCs with Cr/Sn ratios 0.02, 0.05, and 0.10 showed increased overall photon-to-electricity conversion efficiency from that of pure SnO(2). Especially, the DSSC with the Cr/Sn ratio 0.02 showed a remarkably large increase by 55%. The electrode materials were analyzed by powder X-ray diffraction, transmission electron microscopy, N(2) adsorption studies, and UV-Vis diffuse reflectance spectroscopy. The Cr-containing species appears to be Cr(2)O(3) nanoparticles, spread evenly on the SnO(2) nanoparticles and filling the gap space between SnO(2) particles. The electrochemical properties of the electrodes were characterized by Mott-Schottky plots and electrochemical impedance spectroscopy. As the Cr-content increases, the flat-band potential is negatively shifted. The impedance spectroscopy data show that Cr/Sn = 0.02 and 0.05 samples have lower charge transport resistance at the electrode, which can be explained by the rise of the conduction level due to the charge transfer from the more basic Cr(2)O(3) nanoparticles to SnO(2) nanoparticles. These observations corroborate with the trends of the short-circuit current and the open-circuit voltage of the DSSCs.     

Tin/polypyrrole composite anode using sodium carboxymethyl cellulose binder for lithium-ion batteries

A tin nanoparticle/polypyrrole (nano-Sn/PPy) composite was prepared by chemically reducing and coating Sn nanoparticles onto the PPy surface. The composite shows a much higher surface area than the pure nano-Sn reference sample, due to the porous higher surface area of PPy and the much smaller size of Sn in the nano-Sn/PPy composite than in the pure tin nanoparticle sample. Poly(vinylidene fluoride) (PVDF) and sodium carboxymethyl cellulose (CMC) were also used as binders, and the electrochemical performance was investigated. The electrochemical results show that both the capacity retention and the rate capability are in the same order of nano-Sn/PPy-CMC > nano-Sn/PPy-PVDF > nano-Sn-CMC > nano-Sn-PVDF. Scanning electronic microscopy (SEM) and electrochemical impedance spectroscopy (EIS) results show that CMC can prevent the formation of cracks in electrodes caused by the big volume changes during the charge-discharge process, and the PPy in the composite can provide a conducting matrix and alleviate the agglomeration of Sn nanoparticles. The present results indicate that the nano-Sn/PPy composite could be suitable for the next generation of anode materials with relatively good capacity retention and rate capability.     

Self-assembly of disk-like multiring ZnO-SnO2 colloidal nanoparticles

ZnO-SnO(2) colloidal nanoparticles have been successfully synthesized by using the composite of ZnCl(2) and Sn(OC(4)H(9))(4) as inorganic precursor and dodecylbenzenesulfonic acid (DBSA) as an organic template. The assembled nanostructures of ZnO-SnO(2) products have been carefully investigated by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). It is found that ZnO-SnO(2) colloidal nanoparticles take a disk-like multiring nanostructure. This interesting structure is predominantly determined by the tenacity for ZnO-SnO(2) mixtures to stabilize lamellae. A mechanism based on electrostatic interactions between the precursor and template has been proposed to illustrate the resulting nanoparticle structure.     

Preparation of Ni/TiO2 Nanoparticles and Their Catalytic Performance on the Thermal Decomposition of Ammonium Perchlorate

Metal/oxide nanoparticles are attractive because of their special structure and better properties. The Ni/TiO₂ nanoparticles were prepared by a liquid phase chemical reduction method in this paper. The obtained‐products were characterized by inductively coupled plasma (ICP), X‐ray diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The results show that Ni particles in Ni/TiO₂ nanoparticles exhibit better dispersion and the size of most Ni particles is 10 nm or so. The catalytic activity of Ni/TiO₂ nanoparticles on the thermal decomposition of ammonium perchlorate (AP) was investigated by simultaneous thermogravimetry and differential thermal analysis (TG‐DTA). Results show that composite process of Ni and TiO₂ can improve the catalytic activity of Ni nanoparticles on the thermal decomposition of AP, which is mainly attributed to the improvement of Ni dispersion in Ni/TiO₂ nanoparticles. The catalytic activity of Ni/TiO₂ nanoparticles increases with increasing the weight ratio of Ni to AP.     

Nanocrystalline tin as a preparative tool: synthesis of unprotected nanoparticles of SnTe and SnSe and a new route to (PhSe)4Sn

The reactions of nanocrystalline tin metal (Sn*) with elemental selenium and tellurium and with the diaryldichalcogenides Ph2Se2 and Ph2Te2 have been investigated. Reaction of Sn* with the soluble tellurium source Ph2Te2 led to a clean formation of nanoparticles of cubic SnTe. Dependent on the concentration of Ph2Te2, the particles sizes could be varied between 15 and 60 nm in average, whereas the reaction of Sn* with Ph2Se2 formed molecular Sn(SePh)4 in high yield. The latter molecular compound was thermolyzed at 300 degrees C, yielding nanocrystalline SnSe with a broader distribution of size. The nanoparticles of SnTe were thoroughly investigated by transmission electron microscopy (TEM) and powder X-ray diffraction. The reactions of Sn* with elemental selenium and tellurium gave single- phase but microcrystalline SnSe and SnTe.     

经不同浓度FeCl_2溶液处理的γ-Fe_2O_3/Ni_2O_3复合纳米微粒的结构及磁性研究

使用化学共沉淀法制备FeOOH/Ni(OH)_2前躯体,经FeCl_2溶液处理后得到表面包裹2FeCl_3·5H_2O层的γ-Fe_2O_3/Ni_2O_3复合磁性纳米微粒。分别制备了经不同浓度FeCl2溶液处理后的复合磁性纳米微粒,并通过振动样品磁强计(VSM)、X射线衍射仪(XRD)、透射电子显微镜(TEM)和X射线光电子能谱仪(XPS)对样品的结构和磁性能进行分析。实验结果表明,微粒的磁性并不随FeCl_2处理液浓度的增加而单调变化。文中系统分析了FeCl_2溶液浓度对所制备微粒的磁化性质、形态及化学成分的影响。     

核/壳型CdTe@SiO2荧光纳米复合粒子的制备与表征

利用反相微乳法, 以巯基乙酸修饰的水溶性CdTe量子点为核, 包覆SiO₂, 制备得到核壳型CdTe@SiO₂荧光纳米复合粒子. 用紫外-可见(UV-vis)分光光度计, 荧光(PL)分光光度计, 红外(FT-IR)光谱仪, 透射电子显微镜(TEM)等分析测试手段, 对得到的荧光纳米复合粒子的性能进行表征, 结果表明: 得到的CdTe@SiO₂纳米复合粒子是核壳型结构, 由SiO₂壳层包覆多个量子点, 其大小均匀, 水溶性好, 有效地提高了量子点的稳定性, 大大增强了其抗光漂白性能, 为该材料的进一步生物应用打下了良好的基础.     

Effect of Nanoparticle Size on Gas-sensing Properties of Tin Dioxide Sensors

Sn(OH)₄ was prepared by the conventional solution precipitate method, followed by supercritical CO₂ drying. The resultant Sn(OH)₄ was divided into three aliquots and calcined at 400, 600 and 800℃, respectively, thus SnO₂ nanoparticles with average crystallite sizes of 5, 10 and 25 nm were obtained. Furthermore, three SnO₂ thick film gas sensors(denoted as sensors S-400, S-600 and S-800) were fabricated from the above SnO₂ nanoparticles. The adhesion of sensing materials on the surface of alumina tube is good. Compared to the sensors S-600 and S-800, sensor S-400 showed a much higher sensitivity to 1000 μL/L ethanol. On the other hand, sensor S-800 showed a much lower intrinsic resistance and improved selectivity to ethanol than sensors S-400 and S-600. X-Ray diffraction(XRD), transmission electron microscopy(TEM) and selective area electron diffraction(SAED) measurements were used to characterize the SnO₂ nanoparticles calcined at different temperatures. The differences in the gas sensing performance of these sensors were analyzed on the basis of scanning electron microscopy(SEM).