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本文用柠檬酸三钠还原硝酸银的方法制得银纳米粒子,并且通过调节加入正硅酸乙酯(TEOS)的量形成不同包裹厚度的Ag@SiO2。用紫外可见吸收光谱、扫描和透射电子显微镜测试手段对样品进行了分析和表征。获得了比较均匀的银纳米颗粒,加入TEOS后,在银纳米颗粒的周围包裹了一层二氧化硅膜,形成分散性较好的Ag@SiO2纳米颗粒。通过吡啶分子来探测不同SiO2厚度的Ag@SiO2的包裹致密性以及增强效果,选出增强效果最好的Ag@SiO2作为SERS基底,并把它运用于检测农药的残留问题。实验结果表明当加入1!L的TEOS时形成的Ag@SiO2纳米颗粒包裹得均匀致密并且拉曼增强效果很好。
In this paper, silver nanoparticles were prepared by reducing silver nitrate with trisodium citrate, and Ag @ SiO2 with different coating thickness was formed by adjusting the amount of tetraethyl orthosilicate (TEOS). The samples were analyzed and characterized by UV-Vis, scanning and transmission electron microscopy. Obtained a more uniform silver nanoparticles, adding TEOS, the silver nanoparticles wrapped around a layer of silica film to form a better dispersion of Ag @ SiO2 nanoparticles. By using pyridine molecules to detect the packing density and the enhancement effect of Ag @ SiO2 with different SiO2 thickness, Ag @ SiO2 with the best enhancement effect was selected as the SERS substrate and applied to detect the residue of pesticides. The experimental results show that the Ag @ SiO2 nanoparticles formed when 1 L TEOS is added are uniformly and densely packed and the Raman enhancement effect is very good.