Design Of Surface Plasmons Structures Based On Low-Dimensional Materials And SERS Applications

Surface plasmons are collectively coherent oscillations of free electrons that exist at the metal-dielectric material interface.It includes two types:localized surface plasmons and propagating surface plasmons.Near the nano-gap between the metal-dielectric material interface and the metal-metal,the energy density of light and the local electric field strength are greatly enhanced,forming“hot spots”.Therefore,surface plasmons can effectively promote the interaction between light and matter in nanophotonics systems.This remarkable feature makes it widely applied in nano-lasers,solar cells,catalysis,biochemical sensing,surface-enhanced Raman scattering,and so on.The preparation of plasmonic nanostructures with excellent-performance that can be conveniently used in various applications is the goal that researchers are tirelessly pursuing.In this study,we designed experimentally and theoretically the hybrid structure of low-dimensional materials to achieve surface plasmons effect,and discussed the effects of growth parameters and filling components on surface enhanced Raman scattering?SERS?.Thermal evaporation method,annealing process and chemical synthesis were used to prepare uniform metal nanostructures.Chemical vapor deposition method and precursor thermal decomposition method were used to prepare large-area,high-quality graphene and molybdenum disulfide materials film,as a basis for the design of the surface plasmon structure.The theoretical simulation softwares were used to demonstrate the local electric field enhancement distribution of the surface plasmons structures.Combining theoretical design with experimental preparation,surface-enhanced Raman scattering substrates with excellent performance were prepared,and the indicators of the Raman-enhanced substrate were verified by detecting rhodamine 6G molecule.Through experimental design,the prepared surface plasmons structures compositing flexible polymer substrate can in situ realize the detection of toxic and carcinogenic residues by the flexible SERS substrates.The surface plasmons structures and pyroelectric nanogenerater are combined to achieve catalysis and SERS practical analysis of dual functions.The main conclusions are as follows:?1?A zero-dimensional plasmonic nanostructure?Ag₂O@Ag core-shell nanoparticles?was designed.Using rhodamine 6G as a detection molecule,it has been proved that Ag₂O@Ag core-shell nanoparticles have excellent SERS performances?ultra-sensitive,quantitative,uniform and stable detection capabilities?.We further demonstrated the preparation of flexible and transparent Ag₂O@Ag/PMMA SERS substrate,which has good adhesion and could meet the in-situ,real-time and ultra-sensitive detection of pesticide residues(10^-7 M chlorpyrifos pesticide)on any rough and curved fruit and vegetable surfaces.The simple and low-cost flexible SERS sensor has broad application prospect in the field of drug residue detection.?2?A plasmonic nanostructure of Ag gyrus/graphene/Au film was provided.Different silver nanostructures can be prepared by changing the quality of silver used in the simple thermal evaporation process.The Ag gyrus/graphene/Au film SERS substrate has the subnanogap between the Ag gyrus and Au film from graphene.The lateral and longitudinal local surface plasmon resonance effect was enhanced by the narrow nanogaps between the Ag gyrus and between the silver gyrus and Au film.The lateral and vertical hot spots together contribute the powerful electromagnetic fields.The COMSOL Multiphysics software was used to simulate the electric field distribution of the Ag gyrus/graphene/Au film.In addition,the prepared Ag gyrus/graphene/Au film/mica flexible SERS substrate has been applied in the in-situ detection of the carcinogen malachite green molecules on the surface of prawn skin,which proved our proposed Ag gyrus/graphene/Au film surface plasmons nanostructure has promoted the development of sensors in practical applications.?3?A low-cost and simple method was provided to prepare AgNPs/graphene@AuNPs surface plasmons structure.By adjusting the thickness of the thermally evaporated gold film and silver film,and adjusting the transferred graphene layers,the surface plasmons structure with the optimal performance could be designed for SERS detection.We further demonstrated that AgNPs/graphene@AuNPs SERS substrate have high sensitivity,good uniformity,and high reproducibility in experiments.With the help of COMSOL Multiphysics software,the multi-dimensional surface plasmons coupling of AgNPs/graphene@AuNPs structure was theoretically confirmed.Finally,through the sensitive and quantitative detection of toxic substances,the AgNPs/graphene@AuNPs SERS substrate has a wide range of practical application potentials.?4?A novel,simple and low-cost method of the flexible MoS₂@AgNPs/inverted pyramid polymer film surface plasmon structure was provided.First,we demonstrated the successful preparation of this structure using various characterization methods.Then the theoretical analysis of the interaction between the surface plasmons structure and the excitation light was performed using FDTD Solutions software.Further,we used this surface plasmon structure as a SERS substrate to verify its excellent sensitivity,quantitative detection ability,uniformity,reproducibility,stability,and recycling ability.This flexible SERS sensor has good biocompatibility,high flexibility and high transmittance,and is used for in situ detection of carcinogenic molecular solutions.Compared with the traditional SERS substrate,the flexible SERS sensor has the advantages of remote and safe detection,which opens up a new direction for the development of the SERS substrate.?5?It was proved that the graphene/silver nanowire/polyvinylidene fluoride film absorbs light energy to produce pyroelectric effect.By changing the plasmonic structure layers,the electrical signal intensity was adjusted and the pyroelectric effect was verified.Then we demonstrated that the tuning hot charges of the surface plasmons active layer by pyroelectric effect and further enhancing SERS signal of rhodamine 6G molecules and crystal violet molecules were analized.Finally,we used the prepared pyroelectric nanogenerator as the SERS substrate to realize the catalysis of the 4-aminothiophenol oxidation reaction and the oxygen reduction reaction and SERS in situ detection.This highly sensitive,real-time and in-situ detection has a wide range of practical application prospects in environmental protection and other fields.