Preparation Of Ag_core Au_shell Nanowires And Surface Enhanced Raman Spectroscopic Investigation

Surface enhanced Raman spectroscopy (SERS) is one of the powerful tools with high sensitivity in surface science since its discovery. In the recent years, the fast progress of nanoscience became the source for the development of SERS. As a consequence, it resulted in the upsurge in the investigation on the SERS mechanism(s) and application. The well-controlled and periodical structure of nanomaterials enabled us to prepare novel special SERS substrates, which drived the experimental and theortical studies on SERS mechanism(s). In the other hand, SERS might be developed to a diagnostic tool for the novel optical, electrical and surface structure. Therefore, the developments of SERS and nanotechnology are obviously mutually beneficial and complementary in their studies.Based on the relationship between the SERS and nanotechnology, in the present thesis, the single metal nanowires were prepared by the anodic aluminum oxide (AAO) template assisted with AC electrodeposition. By the chemical reduction gold shell was covered onto the silver nanowires with different thickness to prepare AgcoreAushell nanowires. Combined with the appropriate probe molecular strategy, SERS was employed to characterize the surface structure of core-shell nanowires. The main results and conclusions are listed as below:1. Porous AAO template was prepared by two steps method in different acidic solution. From the side view, pores were parallel to each other without cross. The pore diameter was changed with the acidic solution and the duration for expanding the pore.2. Combined with AC electrodeposition technique, Au, Ag, Co and Ni were deposited into the pores, and were obtained after the template etched. The optimal condition was explored.3. With the method of chemical reduction and controlling the concentration of gold salt, gold shell was covered onto the silver nanowires with different thickness to prepare AgcoreAushell nanowires. Result showed the appearance of pinhole effect during the formation of core-shell structure. Thiophenol (TP) and pyridine (Py) were employed as to probe to study the SERS effect on the core-shell nanowires. The results revealed that AgcoreAushell nanowires could be used as SERS substrate.4. Cyclic voltammetric (CV) method was used to characterize the core-shell nanowires. After several cycles, pinhole effect was disappeared due to the surface reconstruction. SERS technique indicated that the pinhole free AgcoreAushell nanowires were obtained by controlling the shell in a certain thickness, and SERS was a useful tool for characterizing the surface structure of nanomaterials.In summary, the preparation of well-controlled nanomaterials provides the novel substrate with high SERS activity, in the meanwhile, SERS with high sensitivity was developed as an efficient tool for studying the surface structure and composition. Both of them are mutually beneficial and complementary.