Synthesis Of Silver Nanoparticles And The Studies Of Their SERS Activity

The progress of nanomaterials suggests its great potential foreground in the fields of synthetic chemistry and materials science, especially form metal nanoparticles with unique chemical and physical properties which have extensive applications in optics, electronics, sensor and bioassays. Their properties are strongly depended on the size and shape of metal nanoparticles. Therefore, it is believed that property-controllable metal nanoparticles will be conveniently produced by tuning their sizes, dimensionalities, compositions and morphologies and expected to be fabricated into functional nanodeviees. Although there have been a lot of reports on the synthesis of nanomaterials, the shape-controllable synthesis is still a challenge for materials and chemistry researchers. Based on the development of metallic silver nanoparticles in the world, this dissertation presents a facile chemical solution method to prepare silver nanoparticles with various morphologies and obtain novel silver nanostructures, the growth mechanism was also studied. This dissertation also investigates application of silver nanoparticles in Surface Enhanced Raman Spectroscopy (SERS). The main results and conclusions of this dissertation are outlined as follows:1. Synthesis rice-like silver nanoparticles. Silver nanorices with complicated stacking sequence were synthesized by a facile polyol process. In this protocol, polyethylene glycol 600 (PEG 600) served as both reductant and solvent to reducing AgNO₃ in the presence of a capping agent poly(vinyl pyrrolidone) (PVP). The microstructure of nanorices was studied by SEM, TEM, SAED, XRD, etc. The growth mechanism was also discussed.2. Synthesis flower-like silver particles. Silver nanoflowers were synthesized by reducing AgNO₃ with ascorbic acid (AA) in the presence of a capping agent PVP in aqueous solutions at room temperature, the particle size was altered by changing the concentration of silver nitrate in reacting solution. The properties of nanoflowers was studied by SEM, XRD, DF, etc. With the help of orientation technique, SEM images can be clearly corresponded with Raman images or spectra, and the incident polarization-dependent SERS of individual particles, dimer and trimer are studied. 3. Preparation a wide variety of silver particles by solvothermal method. Silver nanoparticles were synthesized by reducing AgNO₃ in the presence of a capping agent PVP.