Research On The Controlling Growth And Sers Sensing Of Silver Nanostructures

Silver nanomaterials have excellent physical and chemical properties, can be widely used in the field of electronic industry, catalyst industry, medicine, biological sensors. The properties of silver nanomaterials are mainly determined by their morphology and size, and the controllable growth of silver nanostructures is one of the hotspots in the present study. The branched silver nanostructures with a higher aspect ratio than the rough metal film or smooth nanowires, this high aspect ratio nanostructures makes the SERS effect is good. Secondly, between the branches of the branched structures with each other to form a network structure, many gap bands were formed which can be seen as a local "hot sopts ", these "hot spots" can maintain a strong local electromagnetic field, which has an important contribution to the SERS effect. Therefore, the branched silver nanostructure is a good general SERS substrate. At the same time, the special structure in the optical waveguide transmission, optical absorption materials has the potential application, has attracted the widespread attention.In this study, the branched silver nanostructures with controllable morphology were prepared. Then, the branched structures were assembled on the ITO by electrophoresis. Finally, the obtained thin film was used as substrates for SERS study, and several different kinds of probe molecules were detected. The main results and conclusions are summarized as follows:(1) The controlled growth of branched silver nanostructures was studied. Using light method at room temperature (20 ?), branched silver nanostructures can be prepared for 120 min. Design a set of experiments, found that different concentrations of L-arginine make the branch diameter from 20 run to 200 nm controllable and High concentration of PVP contributes to the growth of the branches. Different concentrations of sodium citrate make the net area controlled. At the same time, the amount of sodium borohydride is the key to form branches.We believe that the dendritic silver nanostructures are formed by the aggregation of nanoparticles.(2) The preparation method of SERS substrate based on electrophoresis is studied. The method is simple and does not change the morphology of the branched structures. The effects of electrophoresis voltage, electrophoresis time, solvent and concentration of suspension on the morphology of the thin film were discussed. By optimizing the electrophoresis process, the uniform and dense branched silver nanostructure thin films were prepared.(3) The enhancement effect of SERS based on branched silver nanostructures was studied. Rhodamine 6G as probe molecules, the application of SERS substrate was detected. Detection signal stability and good uniformity. The linear relationship between the intensity of the Raman signal and the probe molecule concentration can be realized by the qualitative and quantitative detection. The limit of detection was 10-10 M and the enhancement factor of 2.4 x 108. At the same time, the methylene blue and crystal violet molecules were detected, and the limit of detection was 10-8 M. It shows that the structure has good application prospects in environmental monitoring and biological testing.(4) Study the synthesis of branched silver nanostructures and nanoparticles composite structure, through the research on the sample surface enhanced Raman scattering, found in the composite structure of the silver nano particles and the dendritic silver nanostructures as the substrate, because the coupling effect, the Raman enhancement factor phase of single dendritic silver nanostructures improves the one order of magnitude, the detection limit of R6G molecules reached 10-11 M, can be used as micro trace detection.