自组装金纳米粒子及其SERS应用

利用柠檬酸钠还原法制备了粒径均匀的AuNPs,并成功实现了其在APTMS修饰的玻璃表面的自组装,得到表面增强拉曼(SERS)基底。以R6G为探针分子检验了SERS基底的活性,其具有较强的增强性能。探讨了不同粒径AuNPs对SERS基底性能的影响,结果表明SERS基底的增强因子随着粒径的增大而增强。这种自组装策略为低浓度有机污染物的探测提供了一种有效的方法。     

蒸气氧化法制备掺锑氧化锌纳米颗粒的研究

以不同摩尔比的Zn-Sb合金为原料,采用加热蒸发氧化-冷凝的方法在相同的试验条件下获得了纯的和Sb掺杂的ZnO纳米颗粒.纳米颗粒的形貌、结构和化学状态分别通过TEM、HRTEM、XRD和XPS进行了表征.通过TEM观察发现:随原料中Sb量的增加,颗粒形貌由纯ZnO的四针状纳米晶须逐渐变化为棒状、四方形和六方形的颗粒状.六方形纳米颗粒的HRTEM分析表明:颗粒是结晶完好的纤锌矿结构的单晶,(1100)晶面间距比文献报道的纯ZnO的数值大.XRD没有检测到Sb掺杂ZnO纳米颗粒除ZnO外的其它物相,但XPS分析确定了Sb元素存在于纳米颗粒中.讨论了四针状纳米ZnO的形成及Sb的存在对颗粒形态的影响.     

Hierarchical Metal/Semiconductor Nanostructure for Efficient Water Splitting

A hierarchically patterned metal/semiconductor (gold nanoparticles/ZnO nanowires) nanostructure with maximized photon trapping effects is fabricated via interference lithography (IL) for plasmon enhanced photo‐electrochemical water splitting in the visible region of light. Compared with unpatterned (plain) gold nanoparticles‐coated ZnO NWs (Au NPs/ZnO NWs), the hierarchically patterned Au NPs/ZnO NWs hybrid structures demonstrate higher and wider absorption bands of light leading to increased surface enhanced Raman scattering due to the light trapping effects achieved by the combination of two different nanostructure dimensions; furthermore, pronounced plasmonic enhancement of water splitting is verified in the hierarchically patterned Au NPs/ZnO NWs structures in the visible region. The excellent performance of the hierarchically patterned Au NPs/ZnO NWs indicates that the combination of pre‐determined two different dimensions has great potential for application in solar energy conversion, light emitting diodes, as well as SERS substrates and photoelectrodes for water splitting.     

Corona Generation and Deposition of Metal Nanoparticles on Conductive Surfaces and Their Effects on the Substrate Surface Texture and Chemistry

A corona discharge ion bombardment technique was used successfully to generate gold particles of submicron diameters. In a negative corona discharge, the glow region contains electrons, negative ions, and positive ions. Positive ions collided with the negative corona tip electrode, causing it to sputter and emit fine particles of the electrode material. These nanoparticles were deposited on grounded metal substrates or thin mica sheets supported by grounded metal substrates. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the size distribution and deposition pattern of the metal nanoparticles. The diameter of these nanoparticles was dependent upon the material of the electrode and ranged from 20 to 450 nm for gold and from 15 to 240 nm for tungsten. The nanoparticles were deposited on aluminum, mica, and carbon steel test panels for different amounts of time. The electrochemical response of the carbon steel panels exposed to aerated salt solution was measured by direct current (DC) polarization technique before and after the gold nanoparticles were deposited. This technique was employed to determine the changes in the surface chemistry because of the presence of gold nanoparticles, and it proved to be a sensible method for detecting the presence of fine layers of nanoparticles on the metallic substrate. The presence of the gold nanoparticles increased the electrochemical potential E_corr from -0.640 V to -0.211 V, compared with the value for a noncorrosive surface, like that of pure gold, which is 0 V.     

ZnO/Al_2O_3复合纳米颗粒的制备与表征

为研究ZnO/Al2O3复合纳米颗粒在涂料、化妆品等领域的应用,采用直接沉淀法制备了纳米ZnO,用硫酸铝水解生成的Al2O3对纳米ZnO进行了表面改性。采用IR、TEM、SEM、XRD等手段对改性前后的粉体进行表征。分析结果表明,改性后粉体颗粒的团聚现象减轻。粉体的光催化降解甲基橙的实验研究表明,改性后ZnO粉体的光催化活性明显下降,进一步证明纳米ZnO颗粒表面存在Al2O3的包覆层。     

Fabrication of ZnO nanorods using metal nanoparticles as growth nuclei

ZnO nanorods were produced by pulsed laser deposition (PLD). Drops of nanoparticle colloid (gold or silver) were placed on silica substrates to form growth nuclei. All nanoparticles were monocrystalline, with well-defined crystal surfaces and a negative electrical charge. The ZnO nanorods were produced in an off-axis PLD configuration at oxygen pressure of 5 Pa. The growth of the nanorods started from the nanoparticles in different directions, as one nanoparticle could become a nucleus for more than one nanorod. The low substrate temperature used indicates the absence of a catalyst during the growth of the nanorods. The diameters of the fabricated 1-D ZnO nanostructures were in the range of 50-120 nm and their length was determined by the deposition time.     

ZIF-8衍生La掺杂ZnO纳米颗粒的制备及其气敏性能

以ZIF-8及La掺杂ZIF-8为前驱体,经高温煅烧制备ZnO及La掺杂ZnO纳米颗粒.研究了La掺杂对ZnO纳米颗粒的形貌、晶体结构及气敏性能的影响.利用X射线衍射仪、扫描电子显微镜对材料的微结构进行表征,结果表明:La掺杂有利于获得更小粒径的类球形纳米结构,但La掺杂未改变ZIF-8及衍生ZnO纳米结构的晶体结构....     

Liquid-Phase Preparation and Characterization of Zinc Oxide Nanoparticles

Zinc oxide (ZnO) nanoparticles have been prepared by a wet chemical method, from zinc acetate and LiOH ethanol-based solutions. The resulted nanoparticles were dispersed in a solvent. The effect of solvent (ethanol or butanol) and surfactant (polyethylene glycol-PEG 200) on the average size and size distribution of the nanoparticles was investigated by light scattering measurements. Smaller size was observed for ZnO nanoparticles dispersed in butanol and PEG 200. The statistical parameters of the Gaussian size distribution curves were calculated. ZnO nanoparticles have been prepared to be used as seeds on a substrate for the growth of ZnO nanowires. The morphology, surface roughness, crystalline structure, and orientation of the nanoparticles deposed on silicon substrate were characterized by atomic force microscopy and x-ray diffraction, respectively.     

Synthesis of ZnO nanoparticles and their ink-jetting behavior

Zinc oxide (ZnO) nanoparticles were synthesized by ultrasonically-assisted solution process without using any surfactants. The as-synthesized spherical ZnO nanoparticles with diameter of 20 +/- 5 nm possessed crystalline nature with wurtzite hexagonal phase and showed a blue-shifted near band-edge ultra-violet absorption at -340 nm due to quantum confinement effect of ZnO nanoparticles. The as-synthesized ZnO nanoparticles were further formulated as an ink for ink-jet printing application. Jetting and writing of various line patterns on Si and ITO substrates were demonstrated using the as-formulated ZnO ink. UV-treated substrates showed an improvement in the fixation of ink on substrate due to decreased contact angle with controlled surface wettability.     

聚醋酸乙烯酯/纳米ZnO颗粒复合材料的等离子聚合及其光学性能

采用等离子镀膜方法在纳米ZnO颗粒表面沉积一层有机薄膜,制备出聚合物/ZnO复合材料.用高分辨透射电子显微镜(HRTEM)、傅立叶变换红外光谱(FTIR)、光致发光光谱(PL)和紫外-可见吸收光谱(UV-Vi8)对其形貌、结构和性能进行表征,研究了聚合物/ZnO复合材料的光学性能以及聚合物与纳米ZnO颗粒的结合强度.结...     

Magneto-Optical Faraday Rotation in Ce:YIG Thin Films Incorporating Gold Nanoparticles

We report an experimental study on optical and magneto-optical properties of Ce-substituted yttrium iron garnet thin films incorporating gold nanoparticles. Au nanoparticles were formed by heating Au thin film on cubic quartz and garnet substrates in a vacuum chamber and a Ce:YIG layer was deposited on them by the aid of the pulsed laser deposition method. A large enhancement of the Faraday rotation was obtained in the sample with Au nanoparticles on a quartz substrate and the effect of the substrate material on improving the optical and magneto-optical response of samples were investigated.     

纳米氧化锌在抗菌食品包装材料中的应用

目的介绍了纳米ZnO的制备方法、抗菌活性和抗菌机理,及其在食品包装材料中的应用。方法总结国内外对纳米ZnO在食品包装材料中的研究现状,并简要讨论了纳米ZnO在安全方面的问题和未来的发展趋势。结论纳米ZnO不仅可以为包装材料提供抗微生物活性,而且能改善包装材料的性质。纳米ZnO已经开始应用于食品包装材料中。     

Electrical Characteristics of Hybrid Nanoparticle–Nanowire Devices

Gold nanoparticles synthesized by a colloidal method were deposited in an Al₂O₃ dielectric layer of an omega-gated single ZnO nanowire FET. These gold nanoparticles were utilized as localized trap sites. The adsorption of the gold nanoparticles on an Al₂O₃-coated ZnO nanowire was confirmed by high-resolution transmission electron microscopy. In this study, a hybrid nanoparticle-nanowire device was fabricated by conventional Si processing. Its electrical characteristics indicated that electrons in the conduction band of the ZnO nanowire can be transported to the localized trap sites by gold nanoparticles for gate voltages greater than 1 V, through the 10-nm-thick Al ₂O₃ tunneling oxide layer.     

Patterning of Hydrophilic and Hydrophobic Gold and Magnetite Nanoparticles by Dip Pen Nanolithography

Nanoparticles offer unique physical and chemical properties. Dip pen nanolithography of nanoparticles enables versatile patterning and nanofabrication with potential application in electronics and sensing, but is not well studied yet. Herein, the patterned deposition of various nanoparticles onto unmodified silicon substrates is presented. It is shown that aqueous solutions of hydrophilic citrate and cyclodextrin functionalized gold nanoparticles as well as poly(acrylic) acid decorated magnetite nanoparticles are feasible for writing nanostructures. Both smaller and larger nanoparticles can be patterned. Hydrophobic oleylamine or n-dodecylamine capped gold nanoparticles and oleic acid decorated magnetite nanoparticles are deposited from toluene. Tip loading is carried out by dip-coating, and writing succeeds fast within 0.1 s. Also, coating with longer tip dwell times, at different relative humidity and varying frequency are studied for deposition of nanoparticle clusters. The resulting feature size is between 300 and 1780 nm as determined by scanning electron microscopy. Atomic force microscopy confirms that the heights of the deposited structures correspond to a single or double layer of nanoparticles. Higher writing speeds lead to smaller line thicknesses, offering possibilities to more complex structures. Dip pen nanolithography can hence be used to pattern nanoparticles on silicon substrates independent of the surface chemistry.     

纳米SnO2、ZnO及ZnO／SnO2复合材料的气敏性能研究

以ZnO、S如纳米颗粒及ZnO／SnO2复合纳米材料分别作为气敏基料制成旁热式气敏元件,运用扫描电镜观察产物的形貌,用静态配气法对浓度为100ppm的甲烷气体进行气敏性能的测试。结果表明,这几类元件的最佳工作温度及灵敏度差异较大,当工作温度为350℃时SnO2纳米颗粒的气敏性能最佳。此温度下,SnO2响应时间和恢复时间也比纯ZnO纳米颗粒分别缩短了2S和3S。     

基于PEG修饰的ZnO量子点光学特性研究

采用溶胶-凝胶法制备了ZnO量子点, 并采用有机高分子试剂PEG(聚乙二醇, M_w=2000)对其表面进行修饰。借助X射线衍射分析、傅立叶红外光谱、光致发光谱和透射显微镜等测试方法, 研究了PEG表面修饰对ZnO量子点结构和光学性能的影响规律。研究表明, 混合加入的PEG聚合物能够成功地包覆在ZnO量子点表面, 但没有改变量子点的晶体结构, 经PEG表面修饰后的ZnO量子点尺寸变小, 稳定性增强, 分散更均匀。同时经PEG修饰的ZnO量子点在400~500 nm波长区域缺陷态发射峰明显减弱, 表明采用PEG来改善ZnO量子点表面缺陷结构具有良好效果。     

不同形貌金纳米粒子的制备及其光谱特性

本文以柠檬酸三钠(Na3C6H5O7.2H2O)保护的小粒径金胶体为晶种,采用晶种法制备了不同形状的金纳米粒子。利用透射电子显微镜(TEM)和紫外可见光谱(UV-Vis)对所制备的金纳米粒子进行了表征。结果表明,随着晶种量的增加,金纳米粒子的形状依次为水滴状、梭状和球状,并且发现梭状金纳米粒子位于850nm处的多极共振吸收峰。基于表征结果分析了不同形貌产物的可能形成机理。     

Microfluidic Designing Microgels Containing Highly Concentrated Gold Nanoparticles for SERS Analysis of Complex Fluids

Surface‐enhanced Raman scattering (SERS) is one of the most promising methods to detect small molecules for point‐of‐care analysis as it is rapid, nondestructive, label‐free, and applicable for aqueous samples. Here, microgels containing highly concentrated yet evenly dispersed gold nanoparticles are designed to provide SERS substrates that simultaneously achieve contamination‐free metal surfaces and high signal enhancement and reproducibility. With capillary microfluidic devices, water‐in‐oil‐in‐water (W/O/W) double‐emulsion drops are prepared to contain gold nanoparticles and hydrogel precursors in innermost drop. Under hypertonic condition, water is selectively pumped out from the innermost drops. Therefore, gold nanoparticles are gently concentrated without forming aggregates, which are then captured by hydrogel matrix. The resulting microgels have a concentration of gold nanoparticles ≈30 times higher and show Raman intensity two orders of magnitude higher than those with no enrichment. In addition, even distribution of gold nanoparticles results in uniform Raman intensity, providing high signal reproducibility. Moreover, as the matrix of the microgel serves as a molecular filter, large adhesive proteins are rejected, which enables the direct detection of small molecules dissolved in the protein solution. It is believed that this advanced SERS platform is useful for in situ detection of toxic molecules in complex mixtures such as biological fluids, foods, and cosmetics.     

一种新颖的硅量子点-金复合纳米粒子的制备和表征

利用电化学刻蚀法制备的硅量子点的还原特性,通过调整硅量子点与氯金酸的量的比例,可控合成了包含有不同尺寸金纳米颗粒的复合纳米粒子,并通过实验证明了硅量子点与金纳米颗粒的结合。在电化学刻蚀制备硅量子点的同时,通过微波辅助法可以迅速地在硅量子点表面有效地修饰上一部分羧基、羟基或者烷基链,从而间接预先对这种复合纳米粒子进行修饰。这种新型的纳米复合材料具有硅量子点的荧光性质的同时,还具有各种尺寸纳米金的光学性质,具有广阔的应用前景和研究价值。     

Growth of Co-Doped ZnO Ferromagnetic Nanoparticles by Sol-Gel Method

Co-doped ZnO nanoparticles have been synthesized by a simple sol-gel route using zinc acetate dihydrate and cobalt(II) acetate tetrahydrate as precursors. The X- ray diffraction and high-resolution transmission electron microscopy show that Co doping has a significant effect on the crystalline nature of ZnO nanoparticles. Thermal analysis indicates that the Co-doped ZnO system is well stable above 300 ^°C. Raman spectroscopy shows the prominent modes at 331, 434, and 579 cm^?1 with 0–2 % doping, whereas additional modes at 490, 525, and 715 cm^?1 corresponding to secondary phases have also been observed for 3–5 % of Co doping in ZnO nanoparticles. The M–H and M–T curves confirmed the ferromagnetic nature of Co-doped ZnO nanoparticles at room temperature.