SiO2 /Au核壳结构纳米粒子的制备及表征

通过以金纳米粒子为表面晶种和壳生长的方法制备了金纳米壳包覆二氧化硅的复合纳米粒子。采用TEM 和UV-Vis对复合粒子进行了表征和研究，结果表明所得到的复合粒子粒径均匀、金纳米壳光滑完整，且壳厚度可通过反应物的用量来控制。当核半径与壳厚度之比在4到13之间变化时,复合粒子的光学共振峰在可见光区到近红外光区范围内可发生大于500 nm波长的移动。     

金属介电核壳结构复合材料的制备、性质及应用

金属介电核壳结构复合纳米颗粒因其独特的结构而具有许多奇异的性质,尤其表现在表面等离子体共振特性上。通过改变金属纳米颗粒的大小和核壳的相对尺寸,可实现光学共振在很宽波段内的可调特性。这一特性不仅在光子学,而且在生物光子学、生物医学等领域都有广泛的应用前景。本文介绍了几种金属介电核壳结构纳米颗粒的制备、性质及其应用。     

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。     

基于金纳米棒的核壳纳米结构及其光学性质研究

以金纳米棒为核的核壳结构纳米粒子由于它独特的光学性质、结构特点以及在催化、表面增强拉曼散射方面的应用前景,成为目前纳米材料研究的热点之一。本文重点介绍以金纳米棒为核,包覆其他无机材料的核/壳结构之合成方法,同时阐述其结构特征、光学性质以及外界条件对结构和性质的影响。其中,由于金银纳米核壳结构的研究开始最早,研究最为深入,故对其进行重点阐述。最后对以金纳米棒为核的核壳结构未来研究进行了展望。     

多功能核壳结构纳米反应器的构筑及其催化性能

随着纳米科学技术的不断发展,通过调节纳米材料的组成、结构、形貌以及尺寸等,已经能够实现对纳米材料性能调控的目的。为了进一步赋予纳米材料以新的功能,拓展其在材料、化学、生物和医学等领域的应用,开发能够同时实现多种功能的新型纳米材料是非常有意义的。多功能纳米材料的获得方法之一是通过对简单纳米粒子表面包覆具有功能性的材料来实现,形成的复合结构称为核壳结构。核壳结构的核和壳可以由相同或不同的材料组成。通过改变内核和外壳材料的组成、结构以及表面性质等,从而可以赋予核壳结构纳米材料以特殊的光、电、磁、催化、吸附以及生物活性等。在核壳结构的基础上对核与壳进行可控化与功能化的改造,可形成空心结构以及蛋黄壳结构(或称拨浪鼓结构),其中的空腔可作为高效纳米反应器应用于催化的各个分支领域。本综述首先讨论了不同核壳结构纳米反应器的设计,然后重点介绍了这些纳米反应器在催化降解染料污染物、催化加氢反应、催化氧化反应以及催化级联反应这几类反应中的应用。最后,对多功能核壳纳米反应器未来的研究和发展提出了一些展望。     

贵金属纳米材料的液相合成及其表面等离子体共振性质应用

金属中的表面等离子体共振是描述其导带电子在电磁场作用下集体振荡的一个物理概念。金属纳米颗粒由于其表面等离子体共振性质表现出独特的光学应用。本文在相关研究的基础上,综述了具备表面等离子体共振性质的不同形貌及多种复合结构的贵金属纳米材料的制备和应用,并对其发展及应用前景进行了展望。     

贵金属纳米材料的液相合成及其表面等离子体共振性质应用

金属中的表面等离子体共振是描述其导带电子在电磁场作用下集体振荡的一个物理概念。金属纳米颗粒由于其表面等离子体共振性质表现出独特的光学应用。本文在相关研究的基础上,综述了具备表面等离子体共振性质的不同形貌及多种复合结构的贵金属纳米材料的制备和应用,并对其发展及应用前景进行了展望。     

贵金属纳米材料的液相合成及其表面等离子体共振性质应用

金属中的表面等离子体共振是描述其导带电子在电磁场作用下集体振荡的一个物理概念.金属纳米颗粒由于其表面等离子体共振性质表现出独特的光学应用.本文在相关研究的基础上,综述了具备表面等离子体共振性质的不同形貌及多种复合结构的贵金属纳米材料的制备和应用,并对其发展及应用前景进行了展望.     

Reversible encapsulation of nanometer-size polyaniline and polyaniline-Au-nanoparticle composite in starch

In this paper we report a new method of solubilization of polyaniline and polyaniline-Au-nanoparticle composite by encapsulating nanometer-size particles in starch. The solubilization was carried out in the presence of ultrasonic waves. We also report that the encapsulation was completely reversible and the dissolved polyaniline as well as the composite could be recovered by replacement with molecular iodine. In addition, the polymer particles could also replace molecular iodine from starch-iodine complex. UV-Visible and Fourier transform infrared (FTIR) spectroscopic measurements established the reversible nature of encapsulation. Transmission electron microscopic measurements showed that the sizes of the particles encapsulated in starch were on the order of 10-20 nm for both polyaniline and Au-nanoparticle-polyaniline composite particles. X-ray diffraction evidenced the presence ofAu-nanoparticles in the starch-polyaniline-Au-nanoparticle composite. Finally, we also mention here that the dissolved polyaniline could also be recovered as a precipitate by enzyme (diastage) hydrolysis of the polyaniline encapsulating starch.     

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。     

Aerosol assisted chemical vapor deposition using nanoparticle precursors: a route to nanocomposite thin films

Gold nanoparticle and gold/semiconductor nanocomposite thin films have been deposited using aerosol assisted chemical vapor deposition (CVD). A preformed gold colloid in toluene was used as a precursor to deposit gold films onto silica glass. These nanoparticle films showed the characteristic plasmon absorption of Au nanoparticles at 537 nm, and scanning electron microscopic (SEM) imaging confirmed the presence of individual gold particles. Nanocomposite films were deposited from the colloid concurrently with conventional CVD precursors. A film of gold particles in a host tungsten oxide matrix resulted from co-deposition with [W(OPh)(6)], while gold particles in a host titania matrix resulted from co-deposition with [Ti(O(i)Pr)(4)]. The density of Au nanoparticles within the film could be varied by changing the Au colloid concentration in the original precursor solution. Titania/gold composite films were intensely colored and showed dichromism: blue in transmitted light and red in reflected light. They showed metal-like reflection spectra and plasmon absorption. X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis confirmed the presence of metallic gold, and SEM imaging showed individual Au nanoparticles embedded in the films. X-ray diffraction detected crystalline gold in the composite films. This CVD technique can be readily extended to produce other nanocomposite films by varying the colloids and precursors used, and it offers a rapid, convenient route to nanoparticle and nanocomposite thin films.     

甲基丙烯酸甲酯/纳米SiO_2粒子分散液的细乳化和细乳液聚合

对包含纳米SiO2粒子的甲基丙烯酸甲酯(MMA)的细乳化和细乳液聚合行为进行了研究.发现在超声细乳化过程中,90%以上的分散于MMA相的纳米SiO2粒子将从油相逃逸到水相.采用甲基丙烯酸3-(三甲氧基甲硅烷基)丙酯(MPS)偶联剂处理SiO2粒子,可以增加其表面亲油性,抑止这种逃逸,经测定几乎全部SiO2粒子在超声细乳化后仍稳定停留在细乳化亚微液滴中.通过进一步细乳液聚合,得到了分散稳定、界面清晰的包裹有纳米SiO2粒子的聚甲基丙烯酸甲酯复合粒子乳液.     

Composite polyphosphazene membranes doped with phosphotungstic acid and silica

Poly（bis（phenoxy）phosphazene） （SPBPP）/phosphotungstic acid （PWA）/silica composite membranes for fuel cells were prepared. The composite membranes were characterized by using FTIR, TGA and SEM techniquies. Incorporation of PWA particles and silica particles into the SPBPP polymer matrix and a specific interaction between them were confirmed by FTIR spectra. TGA results showed that the composite membranes had high thermal stability. Homogeneous distribution of PWA and silica particles within the SPBPP matrix was verified by SEM micrographs. The doped membranes showed increased water uptake and proton conductivity.     

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.     

Silica-graphene oxide hybrid composite particles and their electroresponsive characteristics

Silica-graphene oxide (Si-GO) hybrid composite particles were prepared by the hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of hydrophilic GO obtained from a modified Hummers method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images provided visible evidence of the silica nanoparticles grafted on the surface of GO, resulting in Si-GO hybrid composite particles. Energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) spectra indicated the coexistence of silica and GO in the composite particles. The Si-GO hybrid composite particles showed better thermal stability than that of GO according to thermogravimetric analysis (TGA). The electrorheological (ER) characteristics of the Si-GO hybrid composite based ER fluid were examined further by optical microscopy and a rotational rheometer in controlled shear rate mode under various electric field strengths. Shear stress curves were fitted using both conventional Bingham model and a constitutive Cho-Choi-Jhon model. The polarizability and relaxation time of the ER fluid from dielectric spectra measured using an LCR meter showed a good correlation with its ER characteristics.     

帽状锡纳米粒子的制备及其表面等离子的共振特性

采用真空热蒸发法在SiO2自组装单层膜上沉积金属锡, 制备了帽状锡纳米结构, 通过扫描电镜(SEM)、原子力显微镜(AFM)、X射线衍射(XRD)仪和Cary 5000紫外-可见-近红外(UV-Vis-NIR)分光光度计对其表面形貌、结构以及光谱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, 表面等离子共振峰位具有明显的可调谐性, 随二氧化硅粒径的增大或锡帽层厚度的增加, 表面等离子共振吸收峰向长波方向移动.     

可见光驱动Au/SrTiO3纳米等离子体光催化剂分解水制氢

采用水热法和光沉积法制备了Au/SrTiO_3纳米等离子体光催化剂。通过XRD、XPS、SEM、TEM、EDS和DRS等技术对光催化剂的结构、组成、形貌、粒子大小和光吸收性质等进行了表征,考察了Au/SrTiO_3纳米光催化剂在可见光照下的制氢性能。结果表明,采用水热法成功合成了SrTiO_3纳米粒子,通过负载Au纳米粒子后,由于表面等离子体共振效应,增强了其对可见光的吸收。此外,测试了不同Au负载量对SrTiO_3光催化剂在可见光照下制氢活性的影响,其中,5%Au/SrTiO_3光催化剂在可见光照下制氢活性最高,并对其光催化反应机理进行了进一步的探讨。