The Application Of Metal Nanoparticles/Graphene/Titania Nanotubes Composites In Surface-enhanced Raman Spectroscopy

Due to the high sensitivity, the characteristic fingerprint peaks, the protection and simplepreparation of sample, Surface-enhanced Raman spectroscopy （SERS） has receivedincreasing attention in these areas of analytical chemistry and environmental trace detection.Recent studies have showed the excellent Raman enhancement of the precious metals as theRaman substrate. The graphene reduced from graphite oxide （rGO） has the structure of bothgraphene and graphite oxide. Other than good physical and chemical properties, its formationof composite materials with the metal nanoparticles lead that the study of graphene-relatedmaterials as SERS Substrates is more and more. In this thesis, we prepared graphene withsilver and gold nanoparticles composites by different methods. And then we studied theinfluence of the morphology of the material on the surface-enhanced Raman to provide atheoretical basis for the preparation of a simple and effective SERS substrate and re-use in thedetection of organic pollutants. So we find a new way out for the SERS substrate that can berecycled.The first chapter summarized the history and development of the SERS technique withthe SERS enhancement mechanism and the main active substrates, and also demonstrated theapplication of SERS technology in various fields.The second chapter introduced two ways to prepare composites of silver nanoparticles（AgNPs）/titania nanotubes （TiO₂NTs） in graphene by direct dropping of the silvernanoparticles and light reduction of silver nitrate. The graphene was reduced from graphiteoxide by Cyclic Voltammetry. The scanning electronic microscopy and Raman spectroscopyand ultraviolet spectroscopy were used to characterize the materials. Subsequently, withingrhodamine6G as a probe molecule, several of the new preparation materials as Ramansubstrate were used to to investigate the reasons of composite materials to produce SERSeffect. We found that the AgNPs/TiO₂NTs and AgNPs/rGO/TiO₂NTs could be the SERSsubstrate. And the SERS effect of the AgNPs/rGO/TiO₂NTs by light restoring was best.The third chapter describes two ways that by dropping Au particles directly, or one stepelectrochemical deposition of graphene and gold nanoparticles modified to TiO₂NTs. Weprepared materials were characterized by scanning electron microscopy and Ramanspectroscopy, and UV spectrophotometry to characterized of nano gold colloids. Throughdetecting Rhodamine6G, we found that the Raman spectroscopy of the substrate materialgraphene has been enhanced after the addition of AuNPs although the Raman peaks ofrhodamine6G was not apparent. However, the AuNPs/rGO/TiO₂was more stable thanAgNPs/rGO/TiO₂because Raman spectroscopy enhancement effect of graphene in AuNPs/rGO/TiO₂was still stable after some days.Chapter IV of this paper, the electrodeposition preparation of a uniform layer of silveron rGO/TiO₂was made as a SERS substrate surface and characterized by scanning electronmicroscopy. Finally this material was applied to testing a variety of common organicpollutants by SERS, experimental results show that this material had a strong SERS effect forrhodamine6G, rhodamine B, pyrene and benzo[a] pyrene. And the detection limit ofrhodamine6G and rhodamine B low to0.1nM, which of benzopyrene and pyrene were1uMand10uM. The material showed the Raman enhancement signal of variety of organicpollutants from the inpact of its own character.