Property Control And Application Exploration Of Heterogeneous Plasmon Nanostructure

Heterostructure plasmonic nanoparticles are consisted of highly conductive metals dielectric,semiconducting,and other metallic components of different shapes or sizes.They exhibit synergistic and new plasmonic properties,which cannot be achieved through physical mixture of single components.Due to the advantages of heterostructure plasmonic nanoparticles with tunable composition and spatial distribution,more plasmonic modes of heterostructure plasmonic nanoparticles can be generated,and more optical fields can be localized into nanoscale edges,tips and gaps.A variety of applications in enhanced spectroscopy,photocatalysis and optical filed control are developed based on these properties.In this dissertation,novel Heterostructure plasmonic nanoparticles were designed.The properties and regulation methods of the heteromeric plasmonic nanostructure were systematically investigated and the application of the Heterostructure plasmonic nanoparticles in enhanced spectroscopy and molecular catalysis was explored.The main contents and results are summarized as follows:1.We have found that the twinned nanotip of the Au NF and the large lattice mismatch between Au and Cu can induce formation of twin defects during the growth process,resulting in asymmetric deposition of Cu atoms,and a new Au–Cu Janus nanojellyfish（JNF）was synthesized using twinned nanotips of Au nanoflower（NF）as seeds.The symmetry-breaking using different sizes of Au NF and Cu nanodomains within the Au–Cu JNF can controllably change the localized surface plasmon resonance from visible to infrared.The asymmetric Au–Cu JNF can induce plasmon coupling between dipolar and multipolar modes,which leads to electric-field enhancement in the near-infrared.In addition,An Au–Cu JNF with multiple LSPR modes was chosen to simultaneously match the excitation and emission bands of the lanthanide-doped upconversion nanoparticles.A 5000-fold enhancement of the upconversion luminescence was achieved by using single plasmonic Au–Cu JNF.This work can provide a guide in the fields of plasmonic catalysis,photothermal conversion and nanomotors.2.The 10⁴-fold and 10¹⁶-fold enhancement of two-photon excited fluorescence and anti-Stokes Raman scattering for two-dimensional material of g-C₃N₄ can be achieved by multiple LSPR peaks of Au@Ag nanorods at fundamental and double frequencies,respectively.The results demonstrate the great advantages of plasmon-enhanced nonlinear optical microscopy for the optical analysis on 2D materials,which can not only effectively improve the optical resolution of nonlinear optical systems,but also provide a new method for single-molecule nonlinear optical signal measurement.3.Au@Ag core-shell NRs are presented for plasmonic sensing of Cu²⁺via etching the Ag shells of the monodispersed NRs,which is further applied to detect the Cu²⁺concentrations in water solution.The detection of the Cu²⁺concentration without pretreatment process is possible by observing the solution color with naked eye and accurately measured by the absorption spectra.The detection limit of 1.3μM was obtained by monitoring the absorption spectra.The plasmonic sensing exhibits a high sensitivity for Cu²⁺detection and also excludes interference from other prevalent ions in the solution.This work exhibits an excellent example of the application of shell-etching for heavy metal ion detection,which provides a potential application in the filed of biology and environmental monitoring.4.The large-area monolayer Ag Cl nanoparticle assembly was achieved by the evaporation method.It was found that CO₂ in the atmosphere can be directly converted into carbon material by Ag Cl nanoparticles under laser irradiation,and the Ag Cl-Ag nanostructures were achieved by using the LSPR effect of the decomposed silver nanoparticles.A series of microarray of Ag Cl-Ag composite structure were fabricated using laser irradiation of self-assembled structure.Compared with the traditional micro-array preparation scheme,this method combines nano-particle assembly and laser scanning technology,which has the advantages of fast and easy control and so on.This method has potential applications in the fields of pattern writing and spectral property regulation.