Preparation and characterization of novel carbon-supported and ceramic nanocomposite materials

Novel “bottom-up” synthetic strategies have been successfully employed for the preparation of carbon-supported and ceramic nanocomposite materials. The “bottom-up” strategy allows control of the final material properties by manipulating parameters at the molecular level of the precursor(s) used. The results of two research projects covering the preparation of nanocrystalline metal alloy catalysts as well as nanocrystalline bismuth composites are discussed, as summarized below.; Alternative power sources are currently an area of interest and intense research effort. Direct methanol fuel cells (DMFCs) have attracted much attention in this area because of their clean conversion of fuel to energy and the benign byproducts of the reaction. One of the primary goals of DMFC research is the development of highly active anode catalysts for the electrooxidation of methanol. A highly active DMFC anode catalyst must be efficient in the activation of methanol and water to yield carbon dioxide, six protons and six electrons. Typically this is accomplished with a Pt-Ru alloy catalyst. Other alloys have been suggested with other oxophilic metals including osmium. Theoretical calculations by others suggest that osmium metal may also be an efficient electrooxidation catalyst. This dissertation details the preparation, characterization, and DMFC testing of Os/carbon, (1:1) Pt-Os/carbon, and (3:1) Pt-Ru/carbon nanocomposites as DMFC anode catalysts.; Thermoelectric materials can be used to generate electric power from a temperature gradient or to produce a temperature gradient using electric power. These types of materials are of great research interest as possible solid-state refrigerants. Typical thermoelectric materials include PbTe, Bi ₂Te₃, as well as other Bi alloys. A great deal of recent research effort has centered on nanostructured thermoelectric materials. Recent theoretical work by others predicts that one-dimensional nanowires of Bi will have greatly enhanced thermoelectric properties. This dissertation details the preparation and characterization of Bi/ceramic nanocomposites using sol-gel processing. Using the same synthetic strategy, Bi-E/ceramic nanocomposites were prepared, where E represents a dopant atom, E = Te, Sb, or Sn. This synthetic strategy might prove useful for the preparation of bulk quantities of nanostructured elemental Bi or Bi alloy materials.