Regulation Of SiO₂ Semiconductor Nanomaterials On The Properties Of Au/Ag Precious Metal SERS Substrates

Since surface-enhanced Raman spectroscopy（SERS）was discovered in 1974,it has been widely used in food safety,electrochemistry,biomedicine and other fields due to its extremely high detection sensitivity.This is a technology comparable to single molecule fluorescence technology.However,a fatal flaw is that only very few precious metals and alkaline metalshave a high SERS effect.Alkaline metals are difficult to exist in elemental form in the natural environment.Therefore,the materials used as SERS active substrates are mainly gold,silver and copper.The law of SERS activity of the three is silver>gold>copper.However,because silver nanoparticles are easily oxidized in the natural environment and lose their Raman activity,their practical application is hindered.In addition,the morphology of silver nanoparticles is difficult to control,making the substrate less universal,which greatly limits the practical application of SERS.Therefore,there is an urgent need to develop a SERS active substrate that is simple,fast,convenient,and has high sensitivity,good repeatability,and strong stability.The main research content of this article:（1）By hydrolyzing ethyl orthosilicate（TEOS）and depositing SiO₂ on the surface of silver particles,Ag@SiO₂ particles of different thicknesses were prepared,and the SERS effect of Ag@SiO₂ particles was measured with octylphenol（OP）as a probe.The concentration of OP,the thickness of the shell of the particles and the concentration of the particles are linked to various factors.The minimum detection limit of OP is 1μg/L.Compared with other detection technologies.It is very simple and highly sensitive.On the one hand,it can obtain a better SERS enhancement effect,and at the same time,it can avoid the agglomeration of silver particles and guarantee the stability of the substrate.（2）Au@SiO₂ nanoparticles with different core sizes and different shell thicknesses were prepared by Stober method.The surface-enhanced Raman scattering of nanoparticles with the same shell thickness and different core sizes was studied.According to the FDTD method,particles under real conditions Simulate the coupling of nearby electromagnetic fields.The results show that when the core size is the same ones,due to the increase in shell thickness,the electromagnetic field coupling strength near the particles continues to decrease.When the shell thickness is consistent,the core size increases,the electromagnetic field coupling strength near the particles continues to increase;the larger the particle size,the more the shell The thinner,the stronger the electromagnetic field coupling strength in the vicinity of the nanoparticles.（3）Apply the obtained optimized nanoparticles to the actual life to study the adsorption behavior of probe molecules on the surface of nanoparticles.The results show that when the concentration of probe molecules is the same as the concentration of nanoparticles,the best nanometers will be obtained.Particle surface adsorption.This provides a reliable basis for obtaining the Raman signal of molecules at ultra-low concentration in the future.