Fabrication Of Noble Metal/2D Material Composite Substrates And Their SERS Performance

Noble metal nanoparticles have excellent surface-enhanced Raman scattering(SERS)properties,which have been a hot spot in the field of SERS in recent years.However,pure noble metal nanoparticles being SERS substrates has many defects,such as easy agglomeration,low enhancement ability of two-dimensional(2D)particle substrates,difficult preparation of 3D particle substrates,and small amount of adsorption to detect molecules.In view of these defects,noble metal nanoparticles with strong electromagnetic enhancement effect and graphene or its analogues with large chemical enhancement,easy enrichment of surface molecules,fluorescence quenching during Raman analysis and passivation protection of particles from oxidation under ordinary circumstance are combined to prepare composite substrates,which will undoubtedly combine the advantages of the two types of materials to obtain optimal performance.In this thesis,the SERS substrates composed of Au or Ag nanoparticles and graphene(or graphene oxide,abbreviated as GO)or h-BN are designed and prepared by a new pollution-free process,and the SERS properties of the substrates are studied.The specific research content and innovation points are as follows:1.The multilayer Au/GO superposition structure was fabricated on Si wafer by using physical means,repeated operations of Au sputtering and GO spin-coating followed by annealing.The effects of process parameters(number of layers,Au sputtering time,thickness of GO,annealing temperature and time)on the morphology and SERS properties of the substrate were systematically studied.The results show that due to the synergistic effect of chemical enhancement of GO and electromagnetic enhancement of Au nanoparticles,a strong Rhodamine Raman signal is obtained on the 3D composite,and GO can protect Au nanoparticles from oxidation in the natural environment,which enables the activity of the substrate to decrease very little within one month,and the enhancement ability and stability of the composite substrate are significantly improved compared with the single-layer Au nanoparticle film obtained with the same parameters on Si wafer.Also,the result is good that the composite substrate is used for the detection of organic pollutants by simulating the natural environment.2.The Ag nanoparticles/monolayer h-BN film composite was prepared by growing a single-layer graphene like h-BN film by CVD on copper foil,creating the defects(mainly broken boundaries)of the BN film by manual bending,and in-situ depositing Ag nanoparticles at the defects of the BN film using a primary cell reaction composed of Cu/BN/AgNO3.Raman test shows that due to the unique properties of the BN film(large chemical enhancement and strong adsorption capacity for organic molecules)and the large electromagnetic enhancement of the Ag nanoparticles,the composite substrate has great enhancement ability and has great potential in the detection of environmental pollutants.