一维氧化硅/银核-壳型纳米复合材料的制备及其消光性能

Preparation and extinction property of one-dimensional silica/silver nanocomposite with core-shell structure

利用预处理-化学镀法在氧化硅纳米线表面包覆银层，制备出具有一维核-壳结构的氧化硅／银纳米复合材料。结果表明：当Ag（NH3）2^＋浓度为0．05～0．25mol／L时，可在氧化硅纳米线表面形成银包覆层，随着银氨离子浓度的增加，其厚度从数十纳米增加到上百纳米；银壳层由大小不一、纯度很高、面心立方结构的银纳米粒子紧密堆积而成；一维氧化硅／银核-壳纳米复合材料的实测值紫外-可见吸收光谱和采用离散偶极近似理论模拟计算的理论光谱很接近；可见光区的吸收峰和近红外区的吸收峰分别来源于核-壳纳米复合材料横向和纵向偶极表面等离子体共振银层厚度的增加使近红外区的吸收峰发生明显蓝移。

By pretreatment electroless silver deposition, one-dimensional silica/silver nanocomposite with core-shell structure was fabricated by coating silica nanowires with a layer of silver. The results show that a silver layer can be formed on the surface of silica nanowires at the concentration of Ag（NH3）2＋ from 0.05 to 0.25 mol/L, and the thickness of silver layer can be increased from several tens to more than one hundred nanometers with increasing concentration of Ag（NH3）2＋. The silver layer consists of pure silver nanoparticles with face-centered cubic structure and different size. The UV-Vis spectra of one-dimensional silica/silver nanocomposite accord with the theoretic spectra by discrete dipole approximation simulation. The absorption bands locating at the visible and near infrared region come from the transverse and longitudinal modes of surface plasma resonance of nanocomposite, respectively. The increase of silver thickness results in the obvious blue-shift of absorption band at near infrared region.