线状和树枝状银纳米结构、形成机理及表面增强拉曼散射性质(英文)

以聚丙烯酰胺(PAM)为模板,在液相中通过不同浓度的抗坏血酸还原硝酸银能够得到缠结的线状和树枝状银纳米结构.该方法合成条件温和(常温常压)、产率高、成本低、操作简单,并且得到了特殊形貌的缠结收光在谱一对起线的状线和状树银枝纳状米银结纳构.米通结过构透的射形电貌子和显性微质镜进(T行E了M)表,扫征描.研电究子表显明微,镜PA(SMEM对)线、拉形曼产光物谱的和形紫成外起?可了见决吸定性作用.在反应初期,大量新生成的银核被PAM链吸附,小颗粒逐渐长大,进而相连,导致生成了缠结的线状银纳米结构.另外,抗坏血酸的浓度越高,越不利于线状结构的生成.利用对巯基苯胺(PATP)为探针分子研究了银纳米结构的表面增强拉曼散射(SERS)活性,结果表明线状银纳米结构具有较强的表面增强拉曼散射效果.

Synthesis,Formation Mechanism and Surface-Enhanced Raman Scattering Properties of Silver Tangled Nanowires and Dendritic Structures

Silver tangled nanowires and dendritic structures were readily synthesized in high yield by reducing silver nitrate with different concentrations of ascorbic acid in a polyacrylamide (PAM) aqueous solution at mild conditions (normal temperature and pressure). The structures obtained all have tangled morphology, which is different from the silver nanowires reported previously. The structures of the obtained sliver structures were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, and UV-Vis spectroscopy. PAM plays a key role in the formation of these anisotropic nanostructures as the capping agent and as a soft template. During the initial stage, silver nuclei are formed and PAM molecules simultaneously adsorb on their surfaces. Then, small silver particles will collide with each other along the polymer chains leading to the formation of tangled structures. Additionally, a too high concentration of ascorbic acid is unfavorable for the growth of tangled silver nanowires, and dendritic structures are formed. The surface-enhanced Raman scattering (SERS) activity was investigated using p-aminothiophenol (PATP) as a probe molecule. The silver tangled nanowires and dendritic structures show efficient surface enhanced Raman scattering property.