溶剂热合成一维ZnO纳米线及其光学性质

采用简单的溶剂热法合成了超长的一维2nO纳米线.应用X-射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和荧光光谱(PL)对所得材料的结构和光学性质进行表征分析;并对其生长机理进行了探讨.     

Templated Synthesis of Gold Nanorods (NRs): The Effects of Cosurfactants and Electrolytes on the Shape and Optical Properties

Seeded growth of gold nanorods (NRs) has been accomplished in a micellar medium containing mixed surfactants or a high salt concentration. Cetyl trimethylamoniumbromide (CTAB) forms micelles upon which the growth of rod shaped gold nanoparticles occurs. AgNO₃ is introduced into the growth solution to enhance the formation of NRs. The roles of non-ionic surfactants such as Tween and Triton, and of electrolytes such as sodium chloride and potassium chloride have been examined. As the concentration of these additives in the growth solution is increased, the aspect ratio of the NRs increases to a critical limit, after which it decreases again. Upon carefully controlling the content of Triton X-100 or Tween 20 in the growth solution, these non-ionic surfactants assisted in fine-tuning the shape of gold NRs (e.g. rectangular or “dogbone”). The growth pattern of the NRs fits into the model of a soft template formed by the mixture of CTAB and non-ionic surfactants.     

Tunable surface plasmon resonance frequencies of monodisperse indium tin oxide nanoparticles by controlling composition,size, and morphology

Monodisperse indium tin oxide nanoparticles (ITO NPs) with high crystallinity have been synthesized by the rapid thermal injection method and the seed-mediated growth method. We demonstrate that the surface plasmon resonance (SPR) frequencies of ITO NPs can be manipulated from 1,600 to 1,993 nm in near-infrared band by controlling the composition, size, and morphology. The doping Sn concentration in ITO NPs could be controlled via changing the %Sn in the initial feed from 0% to 30%. The shortest SPR wavelength at 1,600 nm with 10% Sn doping concentration indicates highest free electron carrier concentration in ITO NPs, which has direct relationship with doping Sn⁴⁺ ions. Furthermore, we demonstrate that the SPR peaks can also be tuned by the size of ITO NPs in the case of uniform doping. Besides, compared with the ITO NPs, single crystalline ITO with nanoflower morphology synthesized through the one-pot method exhibit SPR absorption peak features of red-shifting and broadening.     

Synthesis and Optical Properties of Mullite Nanowires

Single-crystalline mullite (3Al₂O₃·2SiO₂) nanowires have been synthesized on silicon substrates by forcing aluminum and chromium chloride powders to react under an ammonia gas flow. The diameter and length of the nanowires have uniform diameters of <100 nm and several micrometers, respectively. High-resolution transmission electron microscope and selected-area electron diffraction analyses indicated that the nanowires were almost structural defect free and had a single-crystalline phase with a 〈0001〉 growth direction. The photoluminescence spectra showed that the mullite nanowires reached an emission peak at the center wavelength of 442 nm originating from the Al–O bonds in preference to the Al–O and Si–O bonds in the mullite bonding structure. Comparison of the photoluminescence between as-synthesized, oxygen–annealed, and plasma-etched nanowires indicates that the nanowires have few defects (i.e., oxygen vacancies).     

铟的希夫碱配合物的合成及表征

研究合成了邻香草醛缩邻苯二胺配体,用此配体与无水三氯化铟反应,制得了未见报道的铟金属有机配合物。采用元素分析、核磁共振光谱、红外光谱、X-射线粉末衍射等分析手段对配体、配合物进行表征,推断配合物的结构。     

Synthesis of tellurium nanotubes by galvanic displacement

Tellurium nanotubes with controlled diameter and wall thickness were synthesized by galvanic displacement of cobalt nanowires and their temperature dependent field effect transistor and magnetoresistance properties were systematically investigated. The nanotube diameter was slightly larger than the sacrificial cobalt nanowire diameter with a wall thickness of range from 15 to 30 nm depending on the diameter of cobalt nanowires. Te nanotubes show p-type semiconducting property with the field effect carrier mobility of approx. 0.01 cm²/V s which is relatively lower than other 1D nanostructure. Low mobility might be attributed to porous morphology with small grain size (<10 nm). Temperature dependent mobility also exhibiting a Conwell-Weisskopf relationship to temperatures below 250 K, indicating that the dominant scattering sites are ionized impurity centers. Unique MR behavior was observed from nanotube with a maximum magnetoresistance ratio of 37% at 260 K.     

银/铂双金属中空纳米颗粒的制备及光学性质研究

通过以Ag纳米颗粒为模板的置换和沉积反应，制备了Ag／Pt双金属复合纳米颗粒、用透射电子显微镜（TEM）对颗粒的形貌、尺寸和结构进行了表征，发现复合颗粒具有中空结构．紫外可见吸收光谱（UV-Vis）研究表明，Ag／Pt双金属中空复合纳米颗粒具有单峰的表面等离子共振吸收特征，随着反应溶液中氯铂酸和硝酸银摩尔比的增加，吸收峰先红移后蓝移．表面增强拉曼光谱实验结果表明，Ag／Pt双金属复合纳米颗粒对吡啶分子具有较好的增强效果．     

Synthesis of Fe3O4 nanowire@CeO2/Ag nanocomposites with enhanced photocatalytic activity under sunlight exposure

Ternary magnetic Fe₃O₄ nanowire@CeO₂/Ag nanocomposites have been firstly synthesized by means of hydrothermal and co–precipitation techniques, and their ability to adsorb, photocatalytic degradation organic pollutants, methylene blue present in water, and separate, has been demonstrated. The results show that CeO₂ and Ag nanoparticles are uniformly deposited on the surface of Fe₃O₄ nanowires. The photocatalytic experiments demonstrate that the Fe₃O₄@CeO₂/Ag nanocomposites exhibit remarkably enhanced photocatalytic properties and stability compared to CeO₂, CeO₂/Ag, Fe₃O₄@CeO₂, Fe₃O₄ under natural sunlight exposure. Moreover, excellent photocatalytic degradation efficiency for phenol and MO are also observed. The enhanced photocatalytic performance may be attributed to the synergetic effect of Fe₃O₄ nanowire, CeO₂ and Ag nanoparticles, which lead to the enhanced light harvesting, the promoted charge separation and enhanced adsorption capacity. In addition, the Fe₃O₄@CeO₂/Ag photocatalyst can be easily collected and separated by an external magnet. These results suggest that the nanocomposites could be exploited as potential candidates for solar photocatalysis.     

碳酸钙表面改性剂磷酸酯的合成及其在塑料体系中的应用

本文在较佳合成条件下合成了不同碳链长度的烷基磷酸酯表面活性剂，并对产物进行了表征。该产品用于轻质碳酸钙的改性，当用量为2．5％（改性剂／碳酸钙质量比）时，可明显改善塑料填料CaCO3的表面性能及填充性能，对软PVC体系的加工性能及力学性能有明显的改善作用。且单酯改性的加工性能优于相同碳链长度的双酯。     

Synthesis and Characterization of Tin Disulfide (SnS2) Nanowires

The ordered tin disulfide (SnS₂) nanowire arrays were first fabricated by sulfurizing the Sn nanowires, which are embedded in the nanochannels of anodic aluminum oxide (AAO) template. SnS₂ nanowire arrays are highly ordered and highly dense. X-ray diffraction (XRD) and corresponding selected area electron diffraction (SAED) patterns demonstrate the SnS₂ nanowire is hexagonal polycrystalline. The study of UV/Visible/NIR absorption shows the SnS₂ nanowire is a wide-band semiconductor with three band gap energies (3.3, 4.4, and 5.8 eV).     

Optical properties of Ag nanoparticle-polymer composite film based on two-dimensional Au nanoparticle array film

The nanocomposite polyvinyl pyrrolidone (PVP) films containing Ag nanoparticles and Rhodamine 6G are prepared on the two-dimensional distinctive continuous ultrathin gold nanofilms. We investigate the optical properties and the fluorescence properties of silver nanoparticles-PVP polymer composite films influenced by Ag nanoparticles and Au nanoparticles. Absorption spectral analysis suggests that the prominently light absorption in Ag nanowire/PVP and Ag nanowire/PVP/Au film arises from the localized surface plasmon resonance of Ag nanowire and Au nanofilm. The enhanced fluorescence is observed in the presence of Ag nanowire and Au nanofilm, which is attributed to the excitation of surface plasmon polariton resonance of Ag nanowire and Au nanofilm. The gold nanofilm is proven to be very effective fluorescence resonance energy transfer donors. The fabricated novel structure, gold ultrathin continuous nanofilm, possesses high surface plasmon resonance properties and prominent fluorescence enhancement effect. Therefore, the ultrathin continuous gold nanofilm is an active substrate on nanoparticle-enhanced fluorescence.     

无机液相源模板法制备TiO_2纳米线及光催化性能

以无机盐TiOSO4为原料,采用多孔氧化铝模板技术,通过液相的溶胶-电泳法,制备出直径为30～70nm的TiO2纳米线。试验发现,通过对多孔氧化铝模板孔径形貌的设计,可以对纳米线的结构进行调控。由无机盐原料制备出的纳米线与有机盐原料不同,以硫酸氧钛为原料制备的无机溶胶纳米线,纯TiO2就表现出较高的可见光催化性能,这是锐钛矿纳米晶的表面分布着部分未分解结晶的过氧钛酸黄色络合物所致,它可以吸收可见光使TiO2光敏化而具有可见光活性。     

Gemini Pyridinium Surfactants: Synthesis and Their Surface Active Properties

New pyridinium Gemini surfactants have been synthesized by esterification of renewable fatty acids with halogenated alcohols furnishing respective esters (2‐chloroethyl hexadecanoate, 2‐chloroethyl tetradecanoate, 2‐chloroethyl dodecanoate, 2‐bromoethyl hexadecanoate, 2‐bromoethyl tetradecanoate and 2‐bromoethyl dodecanoate) followed by their subsequent treatment with 4,4′‐trimethylenedipyridine resulting into the formation of title Gemini surfactants: (4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(hexadecanoyl oxy) ethyl) dipyridinium chloride(7), (4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(tetradecanoyl oxy) ethyl) dipyridinium chloride (8), 4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(dodecanoyl oxy) ethyl) dipyridinium chloride (9), (4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(hexadecanoyl oxy) ethyl) dipyridinium bromide (10), (4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(tetradecanoyl oxy) ethyl) dipyridinium bromide (11), 4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(dodecanoyl oxy) ethyl) dipyridinium bromide (12). Their identifications are based on IR, ¹H‐, ¹³C‐NMR, DEPT, COSY and mass spectral studies. Their surface active properties are also evaluated on the basis of surface tension and conductivity measurements and thermal stability of these long chain cationics Gemini surfactants have been measured by thermal gravimetric analysis under nitrogen atmosphere.     

氮化铝纳米线的气–固法制备及光学性能

以三氯化铝和叠氮化钠为原料,用复分解反应制备单晶氮化铝（AlN）纳米线。样品呈灰白色粉末,反应温度为650℃,反应时间为3h,并对该样品进行X射线衍射、透射电镜和选区电子衍射测试分析。结果表明：样品为六方相氮化铝且为表面光滑的长直形圆柱状,直径为50nm左右,长度均在10μm以上,晶格常数分别为a=0.268nm、c=...     

Chiral induction enhanced photocatalytic degradation of methyl orange by Ag@Ag3PO4 and the reaction mechanism

A novel chiral Ag@Ag₃PO₄-NaDC composite was synthesized by chiral induction. SEM, XRD, CD spectrum, FTIR, UV–vis and XPS were used to study the physical and chemical properties of the materials, and the photocatalytic oxidation ability was evaluated with methyl orange as the target pollutant. The results show that the introduction of chirality can obviously promote the light absorption ability, broaden the band gap, enhance the oxidation ability, promote the separation of electrons and holes, greatly enhance the plasma resonance effect of silver nanoparticles, and promote the synergistic effect between silver nanoparticles and silver phosphate. Compared with Ag@Ag₃PO₄, the catalytic degradation ability of chiral Ag@Ag₃PO₄-NaDC is improved by more than 60%. Therefore, the chiral Ag@Ag₃PO₄-NaDC composite exhibits excellent photocatalytic performance. In the degradation of methyl orange by Ag@Ag₃PO₄-NaDC, a large amount of ·O₂^- and h⁺ were formed on the surface, which was the main reason for the oxidation ability.     

弯曲状GaN纳米线的制备及光学性质研究

采用Ga2O3为Ga源,氨气为N源,通过高温化学气相沉积法制备了新颖的弯曲状Ga N纳米线,六方纤锌矿结构,直径约70~100 nm,长度最长可达几十微米,大部分纳米线呈链状,其生长机制呈VLS生长模式。拉曼光谱表明声子振动带有变宽的特征,基于浅施主态向浅受主态的跃迁包括缺陷层、表面态或残留杂质的影响,PL发光在436 nm和467 nm的出现宽峰。     

Unobstructed electron transfer on porous polyelectrolyte nanostructures and its characterization by electrochemical surface plasmon resonance

Thin organic films with desirable redox properties have long been sought in biosensor research. We report here the development of a polymer thin film interface with well-defined hierarchical nanostructure and electrochemical behavior, and its characterization by electrochemical surface plasmon resonance (ESPR) spectroscopy. The nano-architecture build-up is monitored in real time with SPR, while the redox response is characterized by cyclic voltammetry in the same flow cell. The multilayer assembly is built on a self-assembled monolayer (SAM) of 1:1 (molar ratio) 11-ferrocenyl-1-undecanethiolate (FUT) and mercaptoundecanoic acid (MUA), and constructed using a layer-by-layer deposition of cationic poly(allylamine hydrochloride) (PAH) and anionic poly(sodium 4-styrenesulfonate) (PSS). Electron transfer (ET) on the mixed surface and the effect of the layer structures on ET are systematically studied. Under careful control, multiple layers can be deposited onto the 1:1 FUT/MUA SAM that presents unobstructed redox chemistry, indicating a highly ordered, extensively porous structure obtained under this condition. The use of SPR to trace the minute change during the electrochemical process offers neat characterization of local environment at the interface, in particular double layer region, allowing for better control over the redox functionality of the multilayers. The 1:1 SAM has a surface coverage of 4.1 ± 0.3 × 10⁻¹⁰ mol cm⁻² for ferrocene molecules and demonstrates unperturbed electrochemistry activity even in the presence of a 13 nm polymer film adhered to the electrode surface. This thin layer possesses some desirable properties similar to those on a SAM while presenting ∼15 nm exceedingly porous structure for high loading capacity. The high porosity allows perchlorate to freely partition into the film, leading to high current density that is useful for sensitive electrochemical measurements.     

Laser Ablation Synthesis and Optical Characterization of Silicon Carbide Nanowires

Silicon carbide (SiC) nanowires were synthesized at 900°C by the laser ablation technique. The growth morphology, microstructure, and defects in SiC nanowires were characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The Raman scattering study indicated that the Raman peaks corresponding to the TO and LO phonon modes of the SiC nanowires had larger red shifts compared to those of bulk SiC material. The red shift, broadening peak, and the asymmetry of the Raman peak could be explained by the size confinement effect in the radial and growth directions. The growth mechanism of SiC nano-wires was discussed based on the vapor–liquid–solid reaction.     

Synthesis,Magnetic Anisotropy and Optical Properties of Preferred Oriented Zinc Ferrite Nanowire Arrays

Preferred oriented ZnFe₂O₄ nanowire arrays with an average diameter of 16 nm were fabricated by post-annealing of ZnFe₂ nanowires within anodic aluminum oxide templates in atmosphere. Selected area electron diffraction and X-ray diffraction exhibit that the nanowires are in cubic spinel-type structure with a [110] preferred crystallite orientation. Magnetic measurement indicates that the as-prepared ZnFe₂O₄ nanowire arrays reveal uniaxial magnetic anisotropy, and the easy magnetization direction is parallel to the axis of nanowire. The optical properties show the ZnFe₂O₄ nanowire arrays give out 370–520 nm blue-violet light, and their UV absorption edge is around 700 nm. The estimated values of direct and indirect band gaps for the nanowires are 2.23 and 1.73 eV, respectively.     

Synthesis and Optical Properties of Nonlinear Optical Polyarylates

Several polyarylates based on bisbenzylidenoketones have been synthesized by interfacial polycondensation. Two distinct types of polymers have been obtained: guest-host systems and polyarylates with NLO (nonlinear optical) side chains. The dispersion of the linear refractive index (n ₀) is measured over the wavelength range from 800 to 2000 nm. The Holing formula, based on a semiclassical model of a simple harmonic oscillator, is used to calculate the NLO susceptibility X⁽³⁾.