Preparation And Properties Of SERS Substrate With Multi-dimensional Micronano Array Structure

Raman spectroscopy,as a specific detection technology,is widely used in the detection of solid,liquid and gas samples.By detecting the vibration patterns between different molecules,the fingerprint spectrum of each molecule cable is formed.However,in the process of Raman scattering,only a small number of photons interact with substances,and the intensity of Raman spectral signal obtained is extremely low,which makes it impossible to detect substances with low concentration.Therefore,Raman scattering did not receive much attention in the early days when it was discovered.In 1974,after roughing the smooth silver electrode surface,Fleischmann et al.accidentally found that the monolayer pyridine molecules adsorbed on the silver electrode surface had excellent Raman spectra.Later,under the study of people,the principle of this phenomenon was explained,and it was named as surface enhanced Raman scattering(SERS)effect.The research and development of SERS technology successfully solved the problem of low Raman scattering signal intensity.In addition,the progress of nanotechnology also promoted the development of SERS field.Generally speaking,the micro-nano structure array on SERS surface greatly affected the density and distribution of hot spots,and decided the performance of SERS sensors.Based on the design of micro/nano structure on the surface of SERS substrate,this paper prepared a new multi-dimensional SERS substrate,and analyzed and studied its SERS performance effectively by using experimental instruments.In this paper,the multi-dimensional Au/Ag/CuO NWS PVDF self-powered SERS substrate with piezoelectric effect and triboelectrification and the multi-dimensional pyramid Ag/CuO NWS with molecular enrichment effect were prepared.Specific research contents are as follows:1.Fabrication and characteristics of multi-dimensional Au/Ag/CuO NWS PVDF self-powered SERS substrateSelf-powered electronic materials are becoming an attractive research direction,which can generate electric field through mechanical movement on the base surface,so that electromagnetic enhancement can be fully utilized to improve SERS performance in detection,and no further external electrochemical workstations are needed,simplifying the test steps.A series of experimental results on this substrate showed that,in SERS detection,it not only had excellent sensitivity and uniformity,but also could be used to enhance SERS signals through piezoelectric effect and micro-electric field generated by triboelectric excitation.2.Fabrication and characterization of Ag/CuO NWS multi-dimensional pyramid SERS substrateIn this paper,the Ag/CuO nanowires(NWS)/pyramidal PDMS multi-scale structure was reasonably fabricated into multi-dimensional plasmon-coupled SERS substrates with molecular enrichment effect.CuO NWs grow in pyramidal cavities by alkaline etching and form micro/nano multiscale structures.Ag film was decorated on nano-scale structure by physical vapor deposition method,and SERS activity was given.The subwavelength size of Ag/CuO NW also provides a surface rough enough to separate the droplets from the air,reduce the surface energy,and achieve hydrophobic action.In order to prove the SERS activity,the proposed multi-scale micro-nano structure has been successfully applied to the sensitive detection of low concentration of rhodamine 6G(R6G).Interestingly,we also proved that the Ag/CuO NWS multi-dimensional pyramid SERS substrate has excellent molecular adsorbability,which can be used for practical application detection.Our successful detection of a mixture of R6 G,crystalline violet(CV)and Congo red(CR)molecules in turbidities and different p H conditions demonstrates its great potential for in-situ detection of chemical dye molecules in complex environments.This thesis consists of five parts: Chapter one introduces the discovery and research progress of Raman spectroscopy in detail.There is also a brief introduction to the development of SERS technology and the two main enhancement mechanisms in the SERS field.The second chapter introduces the development process of multi-dimensional SERS base,from zero-dimensional "hot spot",two-dimensional "hot spot" to multi-dimensional "volume hot spot".After that,the preparation and characteristics of several common multi-dimensional SERS substrates as well as the application and challenges of multi-dimensional SERS substrates were introduced.In the third chapter,the multi-dimensional Au/Ag/CuO NWS PVDF self-powered SERS substrate was prepared.Due to its self-powered characteristics,the physical enhancement mechanism of SERS substrate could be further improved.The multi-dimensional structure of Au/Ag/CuO NWS PVDF self-powered SERS base also provided high-density hot spots,which was also the reason for its excellent SERS performance.In the fourth chapter,Ag/CuO NWS multi-dimensional pyramid SERS substrate was prepared.The micronano structure array on the surface provided the superhydrophobic performance similar to the surface of lotus leaf.Under the action of capillary force provided by nanowires,the solution could be adsorbed to the surface for Raman detection,which has greater application value.In addition,the substrate can also achieve specific detection of multiple molecules in complex environments.The fifth chapter is a comprehensive summary of the above work.