温和条件下制备形貌可控的羟基磷灰石

在温和条件下采用简单的实验方法成功制备出不同结构和形貌的羟基磷灰石(HAP)纳米粒子。采用沉淀-水解两步法,以PEG和PVP为表面活性剂,在沉淀步骤制备出前驱体CaHPO₄粒子,然后在100℃、常压条件下水解获得高结晶度的HAP纳米棒。采用PEG制备的纳米棒形貌均匀、纵横比高;采用PVP制备的纳米棒尺寸范围较宽且尺寸较小。直接采用一步沉淀法也能够成功制备出HAP纳米粒子。采用PEG制备出麦穗状的纳米粒子;采用PVP制备出尺寸小的纳米棒和纳米粒子混合物。HAP纳米晶的结构和形貌因制备条件不同发生很大变化,故而控制其合成,有望用于生物医药领域。     

温和条件下制备形貌可控的羟基磷灰石（英文）

在温和条件下采用简单的实验方法成功制备出不同结构和形貌的羟基磷灰石(HAP)纳米粒子。采用沉淀-水解两步法,以PEG和PVP为表面活性剂,在沉淀步骤制备出前驱体CaHPO_4粒子,然后在100℃、常压条件下水解获得高结晶度的HAP纳米棒。采用PEG制备的纳米棒形貌均匀、纵横比高;采用PVP制备的纳米棒尺寸范围较宽且尺寸较小。直接采用一步沉淀法也能够成功制备出HAP纳米粒子。采用PEG制备出麦穗状的纳米粒子;采用PVP制备出尺寸小的纳米棒和纳米粒子混合物。HAP纳米晶的结构和形貌因制备条件不同发生很大变化,故而控制其合成,有望用于生物医药领域。     

在SDS-PVP团簇软模板中自组装多脚状金纳米粒子

利用十二烷基硫酸钠(SDS)与聚乙烯吡咯烷酮(PVP)组成的团簇为软模板, 在微波辅助下以柠檬酸钠为还原剂快速还原氯金酸生成金晶并自组装成多脚状金纳米粒子. TEM结果显示, 得到回转直径约为50 nm的多脚状纳米结构, 电子衍射(ED)证实其为多晶结构. XRD结果表明, 该多脚状金纳米结构主要沿(111)晶面生长, 构成该纳米结构的晶粒尺寸约为12.7 nm. SDS与PVP组成的团簇结构对金纳米粒子的形貌有显著影响, 固定PVP浓度时, 随着SDS浓度增大, 金纳米粒子的形貌由球形向多脚状转变, 同时还原产物水溶液的UV-Vis光谱在800 nm附近的吸收逐渐增强.     

聚苯胺包裹的金纳米粒子的合成和表征及初步应用

用苯胺作还原剂还原氯金酸合成了金纳米结构. TEM实验表明, 苯胺还原氯金酸能生成苯胺齐聚物或其聚合物包裹的金球形纳米粒子. XPS分析表明, 金纳米粒子包覆的聚合物层带正电荷. 该纳米粒子能用于电极表面纳米结构组装及氧化还原性的生物大分子的电化学研究, 实现了超氧化物歧化酶(SOD)在这种带正电荷的金纳米粒子表面的直接电子转移.     

乳液聚合法制备纳米金/聚苯乙烯复合粒子

以氯金酸为前驱体,十二烷基硫醇和硼氢化钠分别作为稳定剂和还原剂,采用相转移法制备了单分散的金纳米粒子.将金纳米粒子通过乳液聚合的方法制备了纳米金/聚苯乙烯复合粒子.通过紫外-可见吸收光谱(UV-Vis)研究了纳米金和纳米金/聚苯乙烯复合粒子的光吸收特性,使用傅立叶变换红外光谱(FT-IR)、X射线衍射(XRD)、透射电子显微镜(TEM)和动态光散射(DLS)对产物的组成、晶体结构、形貌、以及粒径进行了表征.结果表明,复合粒子为粒径分布较窄的球形,其中的金纳米粒子为面心立方结构.热失重分析(TGA)说明制备的纳米金/聚苯乙烯复合粒子具有很好的热稳定性.     

金纳米粒子组装体的连续离散型纳米结构控制

采用柠檬酸钠还原氯金酸的方法,制备出粒径均一的金纳米粒子(AuNPs),通过加入二水合双(对-磺酰苯基)苯基膦化二钾盐(BSPP),增强了AuNPs体系的分散性与稳定性.选用直径为15和40nm的AuNPs,用不同序列巯基修饰的单链DNA连接到其表面,通过DNA链的杂交,形成不同结构的金纳米粒子组装体.通过改变加入DNA延长连接单元的比例,可以控制金纳米粒子组装体具有连续离散型的1∶1,2∶1和3∶1纳米结构.     

聚合物保护贵金属纳米粒子的相转移技术

依据聚乙烯吡咯烷酮(PVP)在水中的溶解度随温度升高而降低的特性,建立了将PVP保护的金、银、铂纳米粒子从水相转移到油相的简单而有效的相转移技术.方法是利用电化学还原法先于水溶液中制备粒度均匀的金属纳米粒子,然后向电化学合成后的金属纳米水溶胶中加入适量正丁醇,在搅拌条件下升温至80℃即可使金属纳米粒子从水相转移至有机相.纳米粒子的相转移效率很高,而且相转移后粒子在油相中分散很好,没有团聚现象发生.在此基础上进一步建立在油水混合体系电化学合成金属纳米粒子的实验方法,为收集纳米粒子和制备纳米粒子薄膜提供了新的有效途径.     

纳米金粒子与R-藻红蛋白的相互作用

以NaBH4为还原剂, 采用化学还原法制备了纳米金溶胶, 发现以pH=7的金前驱液还原得到的纳米金粒子具有最强的紫外吸收(525 nm), 当以聚乙烯吡咯烷酮(PVP)为稳定剂时, 此吸收紫移到510 nm. TEM观察金粒子大小为5~8 nm. PVP、聚乙烯醇(PVA)和吐温-80等能较好地稳定纳米金粒子, 而十二烷基苯磺酸钠、PEG-1000和OP乳化剂等则没有稳定作用. 以紫外-可见光谱(UV-Vis)、X光荧光光谱(XRF)、透射电子显微镜(TEM)等研究了纳米金粒子与R-藻红蛋白的相互作用, 发现R-藻红蛋白本身对纳米金粒子具有良好的稳定作用. 当R-藻红蛋白与纳米金粒子共存时, R-藻红蛋白所具有的538 nm吸收带强度有所增强, 并发生紫移, 同时578 nm的荧光强度也明显减弱, 这表明R-藻红蛋白与纳米金粒子的相互作用对R-藻红蛋白的空间结构产生了影响, 导致位于R-藻红蛋白外缘藻红素发色团(PEB)的微环境发生了改变. 凝胶柱层析及分光光度分析结果进一步证实了金纳米粒子与藻红蛋白存在明显的相互作用, 这种相互作用可能与藻红蛋白分子中所包含的氨基基团有关.     

多功能NiFeAu纳米粒子的合成与表征

采用一罐纳米乳液法,以聚乙二醇-聚丙二醇-聚乙二醇(PEO-PPO-PEO)三嵌段共聚物为表面活性剂,通过还原前驱体乙酰丙酮镍、乙酰丙酮铁(Ⅱ)和醋酸金,成功制备了NiFeAu纳米粒子.采用透射电镜和X射线衍射仪分析了NiFeAu纳米粒子的形貌和结构;采用傅立叶变换红外光谱仪分析了三嵌段共聚物在NiFeAu纳米颗粒表面的覆盖情况;采用紫外-可见吸收光谱仪和振动样品磁强计测试了纳米粒子的光学和磁学特性.结果表明,三嵌段共聚物成功地结合于NiFeAu纳米颗粒表面;所制备的纳米粒子粒径分布较窄、结晶性能良好,并兼具光学和磁学特性.     

以聚电解质多层膜为纳米反应器制备Au@Pt核壳纳米粒子

以聚二烯丙基二甲基氯化铵和聚苯乙烯磺酸钠为构筑单元,通过静电层层自组装制备了多层膜,利用薄膜中存在的抗衡阴离子,选择AuCl-4和PtCl2-6作为Au和Pt的前驱体,通过连续的阴离子交换/还原,原位制备了Au-Pt双金属纳米粒子。 紫外-可见分光光度法、透射电子显微镜和能量色散X射线能谱数据表明,在聚电解质多层薄膜中成功地制备了具有核壳结构的Au@Pt双金属纳米粒子。 这种纳米粒子在电化学催化、燃料电池方面具有潜在的应用价值。     

Electrochemical synthesis of gold nanocrystals and their 1D and 2D organization

Size-controlled gold nanocrystals were conveniently synthesized through direct electroreduction of bulk AuCl(4)(-) ions in the presence of poly(N-vinylpyrrolidone) (PVP). PVP greatly enhanced the gold particle formation process and also significantly retarded the gold electrodeposition process, allowing the electrochemical synthesis of gold nanocrystals to be carried out in the form of simple electroreduction. This novel electrochemical method may be extended to synthesis of other noble metal nanoparticles with controllable size on a large scale. The PVPK90-protected gold nanocrystals spontaneously self-assembled into nearly ordered 2D close-packed arrays and interesting 1D nanostructures. The aggregation of unstable PVPK17-protected gold nanocrystals resulted in the formation of ultrathin single-crystalline films. PVP plays multifunctional roles in controlling the size and shape of gold nanocrystals and in inducing individual gold nanocrystals to construct 1D nanostructures. The nanoparticle self-assembling technique based on PVP offers a simple, but effective, path to organize individual gold nanoparticles into various 1D and 2D nanostructured materials.     

Poly(N-vinyl-2-pyrrolidone) (PVP)-capped dendritic gold nanoparticles by a one-step hydrothermal route and their high SERS effect

Dendritic gold (Au) nanoparticles have been successfully synthesized by the one-step hydrothermal reduction of HAuCl4.4H2O using ammonium formate (AF) as a reducing agent in the presence of PVP. Effects of different reactant concentrations on the morphologies of obtained products have been systematically investigated. On the basis of the morphologies of the products observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), it has been found that an excessive number of AF molecules are the origin of the dendritic Au particles besides PVP as a stabilizer. AF molecules serve not only as a reductant but probably also as a capping reagent. The study implies that the use of two or more capping reagents with different adsorption abilities will be beneficial to the formation of hyperbranched Au nanoparticles. The new finding will have the potential to be extended to the construction of other highly branched noble metal nanoparticles only by one-step synthesis. In addition, as an example, application of the dendritic particles as an active material in surface-enhanced Raman scattering has been investigated by employing 4-aminothiophenol molecules as a probe.     

Synthesis of Silver and Gold Nanoparticles by a Novel Electrochemical Method

Spherical silver and gold nanoparticles with narrow size distributions were conveniently synthesized in aqueous solution by a novel electrochemical method. The technological keys to the electrochemical synthesis of monodispersed metallic nanoparticles lie in the choice of an ideal stabilizer for the metallic nanoclusters and the use of a rotating platinum cathode. Poly(N‐vinylpyrrolidone) (PVP) was chosen as the stabilizer for the silver and gold clusters. PVP not only protects metallic particles from agglomeration, but also promotes metal nucleation, which tends to produce small metal particles. Using a rotating platinum cathode effectively solves the technological difficulty of rapidly transferring the (electrochemically synthesized) metallic nanoparticles from the cathode vicinity to the bulk solution, avoiding the occurrence of flocculates in the vicinity of the cathode, and ensuring the monodispersity of the particles. The particle size and particle size distribution of the silver and gold nanoparticles were improved by adding sodium dodecyl benzene sulfonate (SDBS) to the electrolyte. The electrochemically synthesized nanoparticles were characterized by TEM and UV/Vis spectroscopy.     

液相脉冲激光烧蚀法制备高熔点的纳米金属粒子

采用液相脉冲激光烧蚀法成功地制备了高熔点的金属Pt、Ru与Ag纳米粒子. 采用SEM、TEM、ED和紫外-可见吸收光谱表征了纳米粒子的特征. 纳米粒子的粒径基本在数个到数十个纳米的大小范围内. 发现含适量PVP(poly(vinylpyrrolidone))的水溶液有利于纳米粒子的制备, 而且还能够提高纳米粒子悬浮液的稳定性. 该制备方法较简单, 在制备高熔点的纳米金属粒子方面有着其它方法所不能比拟的优势.     

Synthesis of Poly（N-vinylpyrrolidone） Nanofibers Containing Gold Nanoparticles via Electrospinning Technique

Poly(N-vinylpyrrolidone)(PVP)nanofibers containing gold nanoparticles were prepared by electrospinning method.This simple route was used to prepare composites on a large scale,and the syntheses are simple.The optical property of gold nanoparticles in PVP aqueous solution was investigated by UV-Visible absorption spectra.The morphology of the fibers and the distribution of particles were characterized by transmission electron microscopy.The structure of the composite was characterized by Fourier transform infrared spectroscopy.     

Effect of size in oxygen electroreduction on gold over a wide range of pH

The electroreduction of molecular oxygen on polycrystalline gold and 20Au/C nanoparticles synthesized on XC72R soot is studied over a wide range of pH. Changes in the character of the polarization curves and a considerable increase in half-wave potential (～100 mV) upon transitioning from a compact to a nanodisperse metal were established. A triple increase in the exchange currents is observed for nanoparticles relative to polycrystalline gold. It is suggested that the enhancement of the catalytic activity of a nanodisperse metal is a result of changes in the electronic structure of the d-sublevel of surface atoms.     

聚苯胺/贵金属复合纳米材料的可控合成及催化应用

导电高分子/贵金属复合纳米材料因其在催化、传感、表面增强拉曼、光热治疗等诸多领域的应用前景而受到广泛关注.本文主要介绍我们课题组近年来利用可控合成策略制备的负载型和包埋型两种结构聚苯胺/贵金属复合纳米材料,以及利用复合纳米材料的结构和功能特性,对其在多相催化领域的应用、结构与催化性能之间构效关系的探索.     

银纳米线的制备及电催化还原氧性能研究

分别以聚乙烯基吡咯烷酮(PVP),乙二醇作为软模板和还原剂,采用不同晶种(AgCl、Ag)快速合成了银纳米线.通过SEM和TEM表征,证明合成银纳米线材料形貌均一,颗粒含量很少.并且发现以AgCl为晶种合成的银纳米线长径比为200左右(SNWH),而以Ag为晶种合成的长径比为30左右(SNWL).以银纳米线作为电催化氧...     

One-step synthesis of gold and silver hydrosols using poly(N-vinyl-2-pyrrolidone) as a reducing agent

Synthesis of gold and silver hydrosols was carried out in a one-step process by reduction of aqueous solutions of metal salts using poly(N-vinyl-2-pyrrolidone) (PVP). Both kinds of metal nanoparticles were obtained without the addition of any other reducing agent, at low temperatures and using water as the synthesis solvent. Shape, size, and optical properties of the particles could be tuned by changing the employed PVP/metal salt ratio. It is proposed that PVP acts as the reducing agent suffering a partial degradation during the nanoparticles synthesis. Two possible mechanisms are proposed to explain the reduction step: direct hydrogen abstraction induced by the metal ion and/or reducing action of macroradicals formed during degradation of the polymer. Initial formation of the macroradicals might be associated with the metal-accelerated decomposition of low amounts of peroxides present in the commercial polymer.