Study On The Synthesis And Characterization Of Gold And Silver Nanostructures With Controllable Shape

Nano-material is one of the exciting research subjects on material science in recent years. Nano technology is recognized as one of the 21st century's most promising research areas. The nanostructural noble metal, together with the unique physical and chemical properties, has surface effect, volume effect, quantum size effect and quantum tunnel effect. It also has been broadly applied in optical, electrical, thermal, magnetic, catalytic and other fields, and become an important component of nano-materials. Meanwhile, it is important to get the shape-controlled noble metal nanoparticles and design the functional materials because their unique physical and chemical properties can be tuned through controlling over the size, shape and morphology of particles. The main content of this dissertation research is to design a simple and effective method to synthesize size- and shape-controlled gold and silver nanostructures. Structures, morphology and spectra characterization were also carried out by field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), atomic force microscope (AFM), X-ray diffraction (XRD) and UV - visible spectrometer (UV-Visble). The main results of this work are listed as follows:1. Through a modified Polyol procee, we mainly studied the synthesis of Au nanoparticles through thermal reduction (150oC) of HAuCl4 precursor in ethylene glycol (EG) solution with the presence of Poly-vinylpyrrolidone (PVP) and Cetyltrimethylammonium bromide (CTAB). By introducing the surfactants (PVP, CTAB) and regulating the growth process, Au nanoparticles of various shapes were obtained. These works provided a demonstration of the use of surfactants to increase the monodisperse of nanoparticles, growth and reaction rate.2. At room temperatures, a simple and modified method was developed for preparing new shapes of Au nanoplates with different degrees of polymerization of PVP (K30, K60 and K90) in the aqueous solution at room temperature. PVP was used as both reducing agent and surfactant. The growth mechanism for Au micro-plates from the nucleation was proposed. Also, the possible growth process of Au nanoplates was described in this thesis.3. The third part of this thesis presented a polyol process for preparing Ag nanorods (or nanowires). Ag nanorods (or nanowires) with the high aspect ratio were synthesized in EG solution by thermal reduction (150oC) of AgNO3 at the presence of PVP used as capping agent. In addition, in terms of regulating the concentration of PVP and changing the temperature and the solution, we can readily access the Ag nanoplates.4. In the fourth part of this thesis, the monolithic porous silica material was prepared by sol-gel method under normal pressure and the obtained structure was examined by Nitrogen sorption isotherms measurement. Additionally, the specific surface area and the distribution of pore size for samples were mensurated and calculated, respectively.