The Application As SERS Substrates Of Graphene And Graphene-wall And Their Nanocomposite Materials

Raman spectroscopy is a powerful tool which can characterizing the structure of materials. In the Raman spectroscopy, due to ultrahigh sensitivity(up to 108)of surface-enhanced Raman spectroscopy(SERS), it is widespread concerned in the scientific field of physics, chemistry, biology, etc.Generally, there are two enhancement mechanism in SERS, electromagnetic mechanism(EM)and chemical mechanism(CM).Electromagnetic mechanism is based on the localized electromagnetic field, which can Provide a powerful enhancement, and another mechanism is contributed by charge transfer between the molecules and the metal. Many noble metal has excellent physical and chemical properties and its SERS effect is so strong. Among them, Ag is the most prominent. However, the noble metal SERS substrate is difficult to cause a wide range of applications, because of the metal possess a poor stability and adsorption. So searching a SERS active substrate material which has strong adsorption and high stability is critical.Graphene, A two-dimensional crystal with a hexagonal honeycomb lattice structure which was composed of an single layer carbon atom based on sp2-hybridized, its unique optical, electronic and mechanical properties have received much attention in sensing, Energy, detection, optoelectronics and the other fields. Graphene can be used as a SERS substrate with its unique structure which has an excellent adsorption. And the superiority of graphene substrate is attributed to its outstanding stability, it can protect the active layer of the noble metal. Currently, the preparation of graphene metal SERS substrate is mainly transferred graphene onto the substrate, graphene structural damaged and the loose fitting problems between graphene and metal nanoparticles will occur in this process. The emergence of graphene nano-wall(G-wall) makes the graphene SERS substrate research into a new upsurge.The graphene wall can be described as self-assembly, vertical stand, several multilayer graphene sheet with nanostructure, also called Nano carbon film or carbon nanosheets. Its unique three-dimensional structure can be developed a new direction of SERS microstructure substrate. First, the G-wall SERS substrate has a better adsorption, because of the three-dimensional structure of G-wall can make the sample fall into the wall structure. On the other hand, various properties of its three-dimensional structure have been confirmed, such as Foldable, stretchable, lightweight, unbreakable, flexible and so on, it can solve the problem of the traditional SERS substrate which cannot work under the special conditions.In this paper, we grow the graphene on the nickel foam directly, and then the silver nanoparticles were introduced. Through the characterization of the substrate structure, It can be observed the similarity with the ideal structure. Simultaneously, using R6 G as a probe molecule to analysis the detection sensitivity of silver nanoparticles decorated graphene based nickel foam SERS substrate, through the SERS effect contrast with nickel and nickel foam sheets and graphene nickel foam substrate, thereby verify the effectiveness of the silver nanoparticles decorated graphene based nickel foam SERS substrate structure substrate.Next we grow the graphene nano-wall on copper foil, and fabricate a kind of graphene nano-wall SERS substrate(G-SERS). Using R6 G as a probe molecule to analysis the detection sensitivity of G-SERS and through the SERS effect comparison of the different growth time graphene nano-wall, thereby verify the effectiveness of G-SERS structure substrate.At last we use the silver nanoparticles decorating the optimal growth time graphene nano-wall by the method of silver-plated, the SERS effect of the graphene nano-wall will be further enhanced, the adsorption and the stability of graphene nano-wall will be retained, simultaneously. And then, with the comparison between the silver nanoparticles decorated graphene based nickel foam SERS substrate and the silver nanoparticles decorated graphene nano-wall SERS substrate, we can prove the effectiveness of the silver nanoparticles decorated graphene nano-wall SERS substrate.