Synthesis And Characterization Of Polymer-Stabilized Nobel Metal Colloids And Particles

This thesis is focused on the preparation and characterization of ruthenium nanoclusters with controllable particle sizes. It is composed of the following parts: Polymer-stabilized ruthenium colloids and particles prepared in low boiling alcohols, such as n-butanol; polymer-stabilized ruthenium colloids and particles with particular morphology synthesized in n-propanol; various factors affecting the sizes and distribution of ruthenium colloids were also investigated. The thesis makes a systemic summarization on the characteristic, preparation and morphology of transition metal nanoparticles.Nano-materials are the materials whose sizes are within nanometric scale. Nano-materials have unique physical and chemical properties that differs from traditional ones because of these particularities such as "quantum size effect", "surface effect", "quantum tunneling effect" and so on. These materials exhibit the advanced performances for electrics, electronics, optics and catalysis. As catalysts, the nanoparticles in solution act as a bridge between homogeneous catalysis and heterogeneous catalysis, thus attracting increasing attention in recent decades. In this dissertation, we proposed a new route to the preparation of poly(N-vinyl-2-pyrrolidone)(PVP)-stabilized ruthenium colloids and nanoparticles with low boiling point alcohols as reducers. A series of ruthenium nanoparticles with different diameters was prepared by this means. The average diameters of ruthenium can be controlled in a range of 1.2nm-1.8nm with the relative standard deviations less than 0.33 by changing the low boiling alcohol, the reduction temperature, the amount of protective polymer and the concentration of RuCl₃.nH₂O. Of these factors, the amount of protective polymer and the concentration of RuCl₃.nH₂O play a major role in influencing the sizes and morphology of the ruthenium nanoparticles prepared. A deep purple Ru colloids solution was synthesized by changing these factors in n-propanol. Transmission electron microscopy(TEM) photographs shows this ruthenium nanoparticles have a unfamiliar morphology—shuttle like, which have not been reported by others so far. UV-Visible absorption spectrophotometry(UV-Vis), Transmission electron microscopy(TEM), X-ray photoelectron spectrometry(XPS), X-ray diffraction(XRD) were employed to characterize the structure and morphology of ruthenium colloids and particles obtained.Compared with other routes to prepare the soluble ruthenium colloids, there are some advantages in this new route. On the one hand, pure Ru nanoparticles was prepared in virtue of simpler and more flexible means; on the other hand, the Ru colloids solution can be reserved without deposition under normal temperature and pressure for long period. The positive achievement is that the shuttle-like ruthenium nanoparticles was prepared, which may offer a good opportunity for the research of novel Ru catalyst.