Preparation Of Different Morphologies Of Metal Tungstate Nanoparticles

In this dissertation, polyethylene glycol (PEG) was used as a structure-directing agent to prepare PdCo bimetallic hollow nanospheres and dendritic Pd nanostructure. Also, CdWO₄ nanowires and BaWO₄ nanoparticles with different shapes, such as wire-like, rod-like, and hollow spherical, were prepared in different microemulsion systems using octane as oil, undecylenic acid and/or dodecylamine as surfactants. These nanostructures were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray Photoelectron Spectrometer(XPS), X-ray diffraction(XRD), UV-vis spectroscopy, Fourier transform infrared(FT-IR) spectrometer, fluorescence spectrophotometer. The main results were as follows:1. Using PEG as a structure-directing agent, PdCo bimetallic hollow nanospheres with a diameter of about 80 nm a thickness of about 9 nm were for the first time synthesized. This new Pd-containing bimetallic hollow nanostructure was successfully applied to catalyze Sonogashira reaction, which reveals obvious advantages such as environmentally friendly reaction conditions (proceeded in water), the recyclability of the catalyst, simple experimental operation and high yields. The measurements on the electrochemical hydrogen-storage of the PdCo bimetallic hollow nanosphere electrode revealed high electrochemical cyclic stability and larger electrochemical capacities, implying that it might be a premium material for hydrogen storage. The effect of such modification with the Pd-Co nanospheres on the electrochemical properties of the LaNi₅ alloy electrode was examined and compared with the pure LaNi₅ alloy electrode. It is shown that both the discharge potential plateau and the discharge capacity of the LaNi₅ alloy electrode increase with the modification of the Pd-Co nanospheres after activation, especially at high discharge rate.2. Dendritic Pd nanostructures were obtained by the reaction of diamide hydrate with [PdCl₄]^2- in PEG aqueous solution. The mechanism of the growth of the dendritic...