Surface Enhanced Raman Spectroscopic Studies On Au@TiO₂ Nanoparticles And Titanium Electrode

As one of the in-situ spectroscopic techniques with high surface sensitivity in probing the interfacial species, surface enhanced Raman spectroscopy (SERS) has an advantage of investigating processes at metal and interfacial structure. With the development of application of titanium in navigation, petroleum industry, and medicine etc, it shows great importance of SERS studies on the surface behaviors of titanium in electrolytes, especial in corrosion and adsorption behavior of molecules to titanium. As one of the most important oxides of titanium, titanium dioxide (TiO₂) is quite a"hot"catalyst well known of its great friendship to environment and high-efficiency in photocatalysis reactions. In this work, Au@TiO₂ nanoparticles was successfully synthesized and with SERS-enhancement from Au core, photocatalytic reactions was investigated employing SERS. In addition, a novel way of roughing Titanium electrode was achieved which expand SERS application to Titanium. Main work and results as following:Based on the polyelectrolyte-mediated electrostatic adsorption, a novel way of layer-by-layer (LbL) synthesizing Au@TiO₂ nanoparticles has been investigated in this work. A number of experimental detections demonstrated that Au@TiO₂ nanoparticles synthesized through assembling Au on silicon wafers have high-stabilization and well-defined shell thickness, indicating a successful way of synthesis, which could provide a great deal of Au@TiO₂ products conveniently.In SERS studies of probe molecules adsorbed onto Au@TiO₂ nanoparticles, it was also been found that the SERS-enhancement from Au core was decreasing when TiO₂ shell was getting thicker, meanwhile, there proved"pinhole"existing in the TiO₂ shell, which influenced intensity of SERS observably. Additionally, A stretch process in space of nanoparticles to"grow larger"in hydrolysis step was observed. Finally, photocatalytic reactions between Au@TiO₂ nanoparticles and Methylene Blue trihydrate indicated that Au@TiO₂ nanoparticles had quite high activity in catalytic reactions. Together with SERS detections, it may provide deep-insight information of catalytic reactions.After roughing Titanium electrode in different ways, SERS of Pyridine adsorbed on Titanium electrode surface was successfully obtained for the first time in the work, using a highly sensitive confocal microprobe Raman system. The result indicated that the most SERS-active roughened Titanium surface could be obtained at the concentration of hydrofluoric acid 0.33%(wt) and 5 min for etching. According to the formula based on the confocal microprobe Raman system and its definition, surface enhancement factor (G) of roughened Ti electrode was calculated about 100 and the SERS effect of about 1.65 orders exists for Titanium in our experiment and calculation.