电子显微镜技术表征聚乙二醇包覆的银纳米线的显微结构特征

以缓慢的水热合成法制备聚乙二醇(PEG)包覆的银纳米线,并用电子显微镜对其微观形貌和结构进行了表征。PEG是一种对银表面呈弱亲和性的水溶性聚合物,它在银纳米线合成中既作为Ag+的还原剂,又作为银线的包覆剂。扫描电镜和透射电镜表征显示,这种银纳米线的直径为80～300 nm,长度大于100μm;并且其中一部分银纳米线首尾相接形成了闭合纳米线圈,是首例以化学法制取的金属闭合纳米线圈。闭合环状纳米线的形成进一步支持了金属纳米线的融合生长机制。透射电镜和选区电子衍射以及银纳米线横截面切片的透射电镜表征显示,这种PEG包覆的银纳米线具有轴对称的五重挛晶结构。银纳米线经过长时间的水热孵化而保持其五重挛晶结构,这一点与某些文献报道的情况有所不同,说明银纳米线结构及其演化具有一定的复杂性。     

柔性硅纳米线阵列的制备及光催化性能研究

硅纳米线阵列是利用太阳能解决能源和环境问题的重要材料,然而,可用于柔性器件和生物相容性器件的柔性硅纳米线阵列的制备方法非常有限。本文通过化学气相沉积,以及高分子转移的方法,成功制备了具有不同高分子层厚度的柔性硅纳米线阵列,并研究了高分子层厚度对柔性硅纳米线阵列光催化性能的影响。结果表明,高分子层厚度越小,柔性硅纳米线阵列的光催化性能越强。因此,利用本文提出的制备方法得到的高分子层厚度低至5 μm的柔性硅纳米线阵列,具有作为高效柔性太阳能电池和全光解水系统光电极的潜力。同时,该研究结果也为设计具有高效光能转换能力的柔性纳米线阵列提供了重要依据。     

[NiFe/Cu/Co/Cu]n纳米多层线的电化学制备及表征

采用电沉积法,在阳极氧化铝(AAO)模板中制备了[NiFe/Cu/Co/Cu]_n多层纳米线.利用扫描电子显微镜(SEM)及透射电子显微镜(TEM)对纳米多层线的表面形貌及结构进行了表征,纳米线阵列高度有序、直径均一、层状结构清晰,NiFe层厚度约40 nm,Cu层厚度约60 nm,Co层厚度约15 nm,各子层厚度可控.利用X射线能谱分析仪(EDS)对纳米多层线NiFe层的成分进行了测试,Ni,Fe的原子比为4:1.利用X射线衍射仪(XRD)对[NiFe/Cu/Co/Cu]_n纳米多层膜和多层线结构进行了测试,多层膜为面心立方(fcc)结构,多层线NiFe层为面心立方(fcc)结构,Cu层为六方密排hcp(100),Co层为面心立方(fcc)结构.与组成、结构完全相同的多层膜相比,[NiFe/Cu/Co/Cu]_n多层纳米线具有更优越的巨磁电阻性能.     

利用牛血清蛋白合成CdS纳米棒和网状纳米线

采用简单易控、对环境友好的矿化方法, 利用牛血清蛋白(BSA)做模板, 通过Cd2+与硫代乙酰胺(TAA)反应制备了形貌均一的CdS纳米棒和网状纳米线. 分别采用透射电子显微镜(TEM)、X射线能谱(EDS)、X射线衍射(XRD)、荧光(PL)发射谱和导电原子力显微镜(C-AFM)等方法对不同实验温度下制备的CdS样品的结构形貌、成分组成和光学性质及微区电子传输行为进行了表征. 结果表明: 在实验反应温度为20 ℃时, 得到的产物为单分散性好的CdS 纳米棒, 长度为250 nm, 直径为30 nm; 在50 ℃时, 得到网状CdS纳米线, 其长度为2-3 μm; CdS纳米棒和网状纳米线均为立方相闪锌矿结构. 荧光性质的测试表明, CdS纳米棒和网状纳米线具有优良的荧光性能, 电流-电压(I-V)特性的表征表明CdS纳米线具有很好的电导特性.     

有序CdS纳米线阵列的制备和光学特性

应用直流电沉积法在多孔氧化铝模板中制备了高度有序的CdS纳米线阵列,并由XRD、Raman、SEM、TEM和HRTEM等进行物理化学表征.结果表明,沉积在多孔氧化铝模板中的CdS呈六角结构,c轴沿孔长度方向定向生长.紫外吸收光谱研究表明,随着纳米线尺寸的减小,纳米线阵列的吸收边向短波长方向移动,荧光光谱测量显示,CdS纳米线阵列的荧光强度高于氧化铝模板,而且在可见光区的荧光特性与激发波长无关.     

Transmission electron microscopy study of pseudoperiodically twinned Zn2SnO4 nanowires

The ternary oxide functional nanomaterial Zn2SnO4 has been synthesized by the thermal evaporation method. The products in general contain numerous kinds of nanowires. In the present work, a remarkable type of Zn2SnO4 nanowires with a pseudoperiodical twinning structure has been investigated by transmission electron microscopy (TEM). These nanowires with a diameter of about 100 nm grow along the 111 direction. High-resolution TEM examinations suggest that a large fraction of the (111) twin boundaries are extended to a thickness of a few nanometers. The twining plane for the perfect case is localized on the Zn atom layer.     

Synthesis,Physical Properties,and Self‐Assembly of A Novel Asymmetric Aroyleneimidazophenazine

The synthesis, physical properties, and self‐assembly of a novel asymmetric aroyleneimidazophenazine (IZ1) is reported. The as‐prepared IZ1 nanowires display an obvious red fluorescence. A heterojunction light‐emitting diode (LED) device with the structure ITO/IZ1 nanowires/p‐SiC/Al (10 nm)/Ti (80 nm)/Al (380 nm)/ITO was fabricated, and electroluminescence emission with two peaks at about 412 nm and 613 nm was detected with a forward bias ranging from 5 to 10 V.     

Study on morphology of LaFeO3 nanofibers under different voltage connections

Continuous LaFeO₃ nanowires and nanobelts were successfully synthesized using a sol–gel assisted electrospinning method followed by calcination at 500°C in air. The thermal decomposition processes of LaFeO₃ are carefully investigated and the best calcining temperature was found to be 500°C. The two nanofibers obtained were characterized using X‐ray diffraction analysis, which shows single phase and the structure of nanobelts has higher crystallinity than that of the nanowires. The scanning electron microscopy reveals that the diameter of the obtained LaFeO₃ nanowires is 139.3 nm. And the thickness and width of the nanobelts are 80 and 459 nm. Moreover, the electrospun LaFeO₃ nanobelts are endowed with a higher specific surface area compared with the nanowires, which results from the regular one dimensional morphology without any detectable agglomeration and a rough surface.     

Synthesis and Characterization of ZnO Nanowires

Zinc oxide is a wide bandgap (3.37 eV) semiconductor with a hexagonal wurtzite crystal structure. ZnO prepared in nanowire form may be used as a nanosized ultraviolet light-emitting source. In this study, ZnO nanowires were prepared by vapor-phase transport of Zn vapor onto gold-coated silicon substrates in a tube furnace heated to 900 ?C. Gold serves as a catalyst to capture Zn vapor during nanowire growth. Size control of ZnO nanowires has been achieved by varying the gold film thickness…     

双槽法电沉积Cu/Ni多层纳米线有序阵列

以多孔阳极氧化铝（AAO）为模板，采用双槽法电沉积工艺制得高度有序的Cu/Ni多层纳米线阵列。利用扫描电镜（SEM）和透射电镜（TEM）对Cu/Ni多层纳米线进行了表征，观察到纳米线表面平滑，多层结构清晰，各子层厚度均匀，直径约为 100 nm，与AAO模板孔径基本一致。由选区电子衍射（SAED）照片可知，多层纳米线中Cu层和Ni层均为单晶结构。振动样品磁强计（VSM）测试结果表明，Cu/Ni多层纳米线阵列具有明显的垂直磁各向异性，外加磁场垂直和平行于AAO模板表面时，磁滞回线的矩形比分别为 0.701 和 0.101 ，矫顽力分别为 589 Oe和 202 Oe。通过控制铝阳极氧化工艺及电沉积时间，可获得不同直径、不同子层厚度的Cu/Ni多层纳米线阵列。     

Ag核Au壳双金属复合纳米线的制备及其表面增强拉曼光谱研究

采用氧化铝模板结合交流电沉积技术制备纯银纳米线, 然后通过化学还原方法, 并控制加入的金盐的量, 在已制备好的银线表面包裹不同厚度的金壳层, 得到具有核壳结构的Ag_核Au_壳复合纳米线. 采用电子显微镜(SEM, TEM)和表面增强拉曼光谱对该复合结构纳米线进行相关表征, 纳米线的表面形貌与加入的金盐的量有关. 以苯硫酚(TP)和对巯基苯胺(PATP)为探针分子, 研究了此类复合纳米线的表面增强拉曼散射效应. 并以PATP在金银纳米线表面吸附的表面增强拉曼光谱的差别为探针, 表征了复合纳米线表面金的包裹程度, 结果表明一定厚度的包裹程度可制备无针孔效应的核壳结构金银复合纳米线.     

Large-scale preparation of aluminum borate-coated aluminum oxide nanowires

Single-crystal and uniform aluminum borate (Al₄B₂O₉)-coated aluminum oxide nanowires have been synthesized in high purity and in large yield via a reaction of metal aluminum with boron oxide in the presence of carbon nanotubes (CNTs). The aluminum oxide nanowires exhibit a well-crystallized one-dimensional structure with diameters ranging from 50 to 70 nm, and the Al₄B₂O₉ have a coating thickness of about 1-5 nm. CNTs play a crucial role in the formation of the important ceramic nanowires, by providing a platform to grow the composite structure. The growth mechanism was proposed by the detailed microscopy observations.     

Single unit cell thick samaria nanowires and nanoplates

We report on the synthesis of samaria nanowires and nanoplates with a thickness of 1.1 nm. The cross-section of the nanowires is a rectangular shape with dimensions of 1.1 nm x 2.2 nm, which corresponded to the size of two unit cells of samaria. Under optimized conditions, we were able to synthesize as much as 10 g of the nanowires.     

Characterization and field emission properties of ZnMgO nanowires fabricated by thermal evaporation process

In this paper, we investigate the roles of gold catalyst using modified thermal evaporation set-up in the growth process of ZnMgO nanowires. ZnMgO nanowires are fabricated on silicon substrates using different thickness of gold catalyst. A simple horizontal double-tube system along with chemical vapor diffusion of the precursors, based on Fick’s first law, is used to grow the ZnMgO nanowires. Field emission scanning electron microscopy images show that the ZnMgO nanowires are tapered. The optical properties of the ZnMgO nanowires are characterized by room temperature photoluminescence (PL) measurements. The PL studies demonstrate that the ZnMgO nanowires grown using this method have good crystallinity with excellent optical properties and have a larger band-gap in comparison to the pure ZnO nanowires. Field emission characterization shows that the turn-on field for the nanowires grown on the thinner gold film is lower than those grown on the thicker gold film.     

Dye-sensitized solar cells based on anatase TiO2 nanoparticle/nanowire composites

Dye-sensitized solar cells were fabricated based on the composites of anatase TiO2 nanoparticles and single crystalline anatase TiO2 nanowires. Nanoparticle/nanowire composites can possess the advantages of both building blocks, i.e., the high surface area of nanoparticle aggregates and the rapid electron transport rate and the light scattering effect of single-crystalline nanowires. Three different composites were prepared with 5 wt %, 20 wt %, and 77 wt % nanowires, respectively. The performances of composite solar cells were compared with pure nanoparticle cells at a series of film thickness. With low nanowire concentrations (5 wt % and 20 wt %), the composite films maintain similar specific surface area as the pure nanoparticle films, while the composite cells show higher short-circuit current density and open-circuit voltage. An enhancement of power efficiency from 6.7% for pure nanoparticle cells to 8.6% for the composite cell with 20 wt % nanowires has been achieved under 1 Sun AM1.5 illumination (100 mW/cm2). For the composite film with 77 wt % nanowires, the nanowires became the major phase. Their less compact packing resulted in significant decrease of the specific surface area, and thus the current density. However, with the increase of film thickness, the current density showed a continuous increase in the whole thickness range up to 17 microm, indicating the improved electron diffusion length due to the formed nanowire network. The nanowires also helped to preserve crack-free thick films. These results show that employing nanoparticle/nanowire composites represents a promising approach for further improving the efficiencies of sensitized solar cells.     

Preparation of Ag Nanowire @ Au Nanoparticle Hybrid Nanowires and their Influence on the Fluorescence Properties of P3HT

In this study, the galvanic displacement reaction between silver and AuCl₄⁻ was carried out to synthesize a series of silver nanowire (Ag NW) @ gold nanoparticle (Au NP) hybrid nanowires. The influence of Ag NW @ Au NP hybrid nanowires on the fluorescence properties of the poly (3‐hexylthiophene) (P3HT) was investigated. The particle sizes of Au NPs on the hybrid nanowires could be adjusted by varying the reaction time and the concentration of the HAuCl₄ solution. Furthermore, steady‐state fluorescence measurements showed that the fluorescence intensity of the P3HT films was higher on various Ag NW @ Au NP hybrid nanowires compared to that on a bare silicon substrate. This was due to the increase in the intensity of electromagnetic field by the localized surface plasmon resonances of Au NPs and surface plasmon polaritons of Ag NWs from the hybrid nanowires. The results were further confirmed by the Raman spectra of the P3HT films on different substrates.     

Fabrication of semiconductor nanowires by conjugation of quantum dots to actin filaments

We demonstrate the feasibility of fabrication of semiconducting nanowires (quantum dots) using F-actin as a template. Three different approaches of assembling quantum dots into nanowires are described. The nanowires were characterized by fluorescence microscopy.     

基于铜纳米线放大的汞离子高灵敏比色检测法

将滚环扩增技术与铜纳米线相结合进行信号放大,建立高选择性、高灵敏的汞离子比色检测新方法。以链霉亲和素修饰的磁珠为探针捕获和分离基质,将生物素修饰的引物链固定到其表面。汞离子存在时,模板链将通过T-Hg^2+-T作用与引物链结合。加入T4连接酶及DNA聚合酶引发滚环扩增反应形成超长单链DNA。与短单链DNA互补形成的长双链DNA可作为铜纳米线沉积模板,加入盐酸释放出大量铜离子催化底物氧化显色。在0.005~1.0 nmol/L范围,汞离子浓度与吸收信号呈良好线性关系,检出限低至3.7 pmol/L。     

Amorphous feather-like boron nanowires

Large-scale arrays of feather-like boron nanowires have been successfully prepared using magnetron sputtering with a target of highly pure boron and boron oxide mixture. The morphology, microstructure and composition of the feather-like boron nanowires are characterized in detail using scanning electron microscopy, transmission electron microscopy, and electron energy-loss spectroscopy. Elemental mapping has been used to investigate the distribution of boron and oxygen in the boron nanowires. It is revealed that the feather-like boron nanowires possess the microstructure of outer oxidized coating layer and inner pure boron. The thickness of the outer oxidized layer is about 1–2 nm. Our results may provide opportunities to understand the fundamentals of boron chemistry and to fabricate new nanodevices.     

Nanowires Formed by the Co‐Assembly of a Negatively Charged Low‐Molecular Weight Gelator and a Zwitterionic Polythiophene

Conjugated organic nanowires have been prepared by co‐assembling a carboxylate containing low‐molecular weight gelator (LMWG) and an amino acid substituted polythiophene derivative (PTT). Upon introducing the zwitterionic polyelectrolyte PTT to a basic molecular solution of the organogelator, the negative charges on the LMWG are compensated by the positive charges of the PTT. As a result, nanowires form through co‐assembly. These nanowires are visualized by both transmission electron microscopy (TEM) and atomic force microscopy (AFM). Depending on the concentration and ratio of the components these nanowires can be micrometers long. These measurements further suggest that the aggregates adopt a helical conformation. The morphology of these nanowires are studied with fluorescent confocal laser scanning microscopy (CLSM). The interactions between LMWG and PTT are characterized by steady‐state and time‐resolved fluorescence spectroscopy studies. The steady‐state spectra indicate that the backbone of the PTT adopts a more planar and more aggregated conformation when interacting with LMWG. The time‐ resolved fluorescence decay studies confirm this interpretation.