Study On The Regulation Of Plasmon And SERS Properties Of Flexible Three-Dimensional Nanostructures

Surface plasmons(SPs)are the collective oscillations of free electrons at the interface between metal and dielectric.Due to the different boundary conditions of electric field in different metal structures,SPs can be divided into propagating surface plasmons(PSP)propagating on the metal/dielectric interface and localized surface plasmons(LSP)located in metal nanoparticles or nanostructures.SPs show excellent performance in enhanced Raman scattering,and thus surface enhanced Raman scattering technique is developed.Surface enhanced Raman scattering(SERS),as a specific and non-invasive molecular detection spectroscopy technology,has wide applications in fields such as biology and chemistry.At present,there are two widely accepted SERS enhancement mechanisms: electromagnetic field enhancement mechanism(EM)and chemical enhancement mechanism(CM).The study of the EM shows that the enhancement effect of SERS is closely related to SPs.The electromagnetic field generated by the local surface plasmon resonance of SERS substrate is an important factor to enhance the Raman signal.Single molecule detection can be realized by enhancing the weak Raman signal.The spatial structure of SERS substrate and the distribution of plasmon metal will directly affect the electric field density and distribution on the substrate surface,so the research and development of SERS substrate has attracted extensive attention of researchers.Among them,flexible three-dimensional nanostructures have the characteristics of high flexibility,large specific surface area,and rich "hot spots".By constructing a three-dimensional electric field space,the full utilization and regulation of incident light can be achieved,ultimately enhancing the interaction between incident light and the molecules to be tested.This thesis starts with constructing a composite structure of SERS substrate to regulate surface plasmons,explore the preparation method and surface structure of the substrate,and ultimately achieve maximum SERS effect.Large-area flexible nanofibers were prepared by electrospinning technology as support templates for SERS substrates,and stable nanostructures were prepared by hydrothermal method.Uniform metal nanostructures were prepared using physical vapor deposition and chemical reduction methods,which prepared for the design of SERS substrates with different morphologies.Through experimental design,flexible three-dimensional nanostructured substrates with different morphologies were prepared,which realized the control of light field and high utilization of light,and proved the SERS performance of the substrate and the degradation ability of dye molecules.The specific research contents are as follows:1.The synergistic effect of the plasmons of noble metals and the piezoelectric effect of semiconductors is proposed to enhance the photoresponse of PVDF@Ag-ZnO/Au composite nanofiber substrates.Among them,zinc oxide nanorods(ZnO NRs)can effectively separate electron-hole pairs by generating a built-in electric field under the action of piezoelectric effect.Schottky junctions formed by noble metals and semiconductors can accelerate carrier migration to improve the utilization of visible light.In addition,the surface plasmon effect of noble metals can enhance the light response of the substrate and expand the light absorption from the ultraviolet region to the visible region.Through the study of the SERS performance of the substrate,the modulation effect of the piezoelectric effect on the optical response of the substrate is proved,thus enhancing the SERS performance of the substrate.In addition,the substrate can also be used to degrade the dye molecule rhodamine B by combination of piezoelectric catalysis and photocatalysis.The experimental results show that the substrate provides a promising strategy for the utilization of solar and mechanical energy.2.We use the surface plasmons of silver nanoparticles(Ag NPs)and the light capture ability of nickel/iron layered double hydroxides(NiFe LDHs)cavities to enhance the SERS performance of the substrate.Based on flexible PVDF nanofibers,NiFe LDHs and Ag NPs are compounded to form PVDF-NiFe/Ag flexible three-dimensional nanostructure substrate for SERS performance research.Relative to the common two-dimension substrate,PVDF-NiFe/Ag expanded the spatial dimension of the substrate,and the nanostructure of the substrate enhanced the utilization of incident light and enhanced the SERS performance of the substrate.Moreover,the distribution of Ag NPs also takes full advantage of the three-dimensional space advantage of the substrate,resulting in a stronger surface plasmon resonance intensity.In addition,the excellent flexibility and spatial structure of PVDF-NiFe/Ag substrate can realize real-time and rapid in-situ detection of gentian violet dye aqueous solution.