Preparation And Research Of Nano-composite Materials For Surface-enhanced Raman Scattering

Surface-enhanced Raman scattering （SERS） has great potential in the dectection of the extremely minute quantities small molecules. Since it was discovered in 1974, it has been widly used in the detection and research of micro materials in Biological, Chemical and Material science field. According to the strengthening mechanism of SERS, it is known that one of the keys of reinforcing effection is the preparation of the enhance substrate. There are two important keys in the research of enhance substrate. On the one hand is the preparement of novel nanostructure, so as to generate more SERS "hot spots". The other hand is the effective coupling of chemical enhancement mechanism and electromagnetic enhancement mechanism by the research of component of nano-composite material. Up to now, the research on the enhancement substrates has been from the single materials, such as the initial noble metal or semiconductor nanomaterial, to the nano-composite materials. Based on the current research status, in this paper, the preparation and SERS effect of metal/semiconductor and metal/graphene oxide nano-composites were studied.Ag/TiO₂ nano-composite material was successfully prepared in this paper. Ag nanowires were successfully prepared by polyol method, and the forming mechanism was analyzed. N doped TiO2 nanostructures （N-TiO2） were prepared on the surface of Ti using a novel way. By adjusting the reaction conditions, the morphologies of TiO2 nanostructures were successfully controlled, which were related to the absorption coefficient and the photocatalytic effect under visible light. The Ag/TiO2 composite nanostructure was prepared by in situ formation of Ag nanoparticles on the TiO2 nanorods. The result of SERS test shows that the Raman spectroscopy of the R6G molecules has been enhanced by compositing the TiO2 nanorods and Ag nanoparticles. The reason is that the chemical enhancement mechanism of semiconductor materials is coupled with the local electromagnetic field enhancement mechanism of noble metal particles.Ag/graphene oxide nano-composite material was successfully prepared in this paper. The graphene oxide materials were prepared by modified closed oxidation method. The Ag/graphene oxide nano-composite material was prepared by in situ formation of Ag nanoparticles on the graphene oxide. The result of SERS test shows that the SERS enhancement effect of the composite is better than that of the Ag, but lower than that of the Ag/TiO2. The reason is that the unique charge transfer in light of graphene oxide is coupled with the local electromagnetic field mechanism of noble metal particles.