The Morphology Control And SERS Properties Research Of Silver Particles By Chemical Etching Method

With the development of modern analytical techniques,surface enhanced Raman spectroscopy (SERS) is widely used in recent years because of its high detection sensitivity. Because metal substrate with nanoscale roughness is necessary for surface-enhanced Raman scattering effects, the preparation of SERS active metal substrate has become a hot topic. Micron special morphological silver particle with nanoscale roughness which is made of nanoparticles is prepared by using the method of chemical reduction and chemical etching in this article. The enhancement effect of the SERS substrate which is made by the prepared silver particle is detected and analyzed. The influence of reaction concentration, PVP, type of added acid and corrosion time on silver particle morphology and properties are mainly researched in this article. The silver particle surface morphology, lattice type, crystallinity and enhancement effect of the SERS substrate are characterized and analysis through the methods of SEM, XRD and SERS.We choose ascorbic acid as reducing agent to react with silver nitrate under the condition of ice water bath in order to prepare silver particles. We prepare silver particles with uniform size and good monodispersity under appropriate concentration. The silver particles we prepared are stacked in face-centred cubic structure. We research the influence of additives on the morphology and properties of silver particles. We find out that add PVP Can make the arrangement of nanoparticles that form silver particles more orderly. We prepare micro silver particles with special the morphology when the adding acid are citric acid, p-toluenesulfonic acid and phosphoric acid, the surface of these micro scale silver particles is consisting of nanoparticles. The SERS substrate which is made by the prepared silver particle can detect dilute solution as 0.01 mol/L Rhodmine B and 3.2×10^-3 mol/L MBA solution, the enhancement effect of substrate is obvious. The detection sensitivity of substrate is very high when the adding acid is p-toluenesulfonic acid, we can detect 3.2×10^-9 mol/L solution by using this substrate.The silver particle prepared by adding citric acid is etched by different corrosion system. The surface roughness of the silver particle which is etched by nitric acid increases, and its SERS effect improves after etching. The morphology of particles change when we use HCl and other corrosion system as corrodent, and we gain more abundant surface morphology, but the SERS property of the particle that etched by HCl and other corrodent is reduced. So we choose HNO3 as appropriate corrodent to observe the influence of etching time, the surface nanoparticles of silver particle are gradually etched off with the increase of etching time, obvious gap and angle appears on the surface of particles, and the proportion of (111) crystal face increases gradually.The SERS enhancement effect is best when etching time is 8h, the detection sensitivity improves at least one order of magnitude compared with particles before etching.