用双还原法制备三角形银纳米片及其光学性能

Preparation and Optical Properties of Triangular Silver Nanoplates by a Dual-Reduction Method

在硼氢化钠和柠檬酸三钠共存的体系中还原硝酸银,以聚乙烯吡咯烷酮(PVP)为表面活性剂和保护剂,水浴加热制备得到三角形银纳米片,用X射线衍射(XRD)、透射电子显微镜(TEM)、紫外-可见(UV-Vis)吸收光谱、表面增强拉曼散射(SERS)光谱对其进行了表征.结果表明:三角形银纳米片产物为立方相金属银,边长为(100±40)nm,厚度为(10±5)nm;产物表现出与球形银纳米粒子完全不同的吸收光谱;柠檬酸根在银晶核不同晶面的选择吸附、PVP的包覆作用及Ag(111)晶面的层错对产物的形成起决定作用;与球形纳米颗粒相比,三角形银纳米片膜对吡啶(Py)分子有显著的SERS活性.

Triangular silver nanoplates were successfully prepared by a water-bath heating method.NaBH4 and sodium citrate were both used as reducing agents while polyvinylpyrrolidone （PVP） was used as a surfactant and protective agent.The product was characterized by X-ray diffraction （XRD）,transmission electron microscopy （TEM）,UV-Vis absorption spectroscopy,and surface-enhanced Raman scattering （SERS） spectrum.The product has a cubic face-centered Ag structure.The triangular silver nanoplates have a border size of （100±40） nm and a thickness of （10± 5） nm.A growth mechanism is proposed to account for the formation of triangular nanoplates.The preferential absorption of citrate on different crystal planes of silver nuclei,the encapsulation function of PVP and the existence of lattice defects in silver crystals plays a significant role in the formation of products.Compared with spherical nanoparticles,the triangular silver nanoplates exhibit a different absorption spectrum and strong SERS activity for pyridine （Py） molecules.