Oxides of the 1st Row Transition and Group III Metals: Investigating Novel Gas-Phase and Non-Hydrolytic Synthesis Routes, and Possible Bactericidal and Energy Applications

In this work, chemical and physical synthesis methods were explored to synthesize 1st transition and group III metal oxide nanomaterials for possible energy and biochemical applications. A chemical vapor deposition method was used to synthesize gallium oxide (Ga2O3) nanostructures on Si(100) substrates with a 10 nm gold catalytic seed layer. A monoclinic β-Ga2O3 crystal phase was determined by Powder X-Ray Diffraction (XRD). X-Ray Fluorescence (XRF) assisted with elemental analysis by confirming presence of gallium. Scanning Electron Microscopy (SEM) was used to visualize the morphology and measure the size of the structures. Initial investigations towards adjusting parameters resulted in microstructures of varying morphologies. Further exploration into the effects reaction vessel reuse had on the size and morphology of β-Ga2O3 structures provided insight into a possible variable related to β-Ga2O3 buildup. Reaction vessels that were used less had nanowires 40 to 80 nm in thickness. As reaction vessels were used more, size and morphology changed into microstructures such as clusters, ribbons, and rods up to 2.8 µm in size. Optical properties investigated by photoluminescence spectra displayed blue and green emission peaks suggesting defects relating to gallium and oxygen vacancies and oxygen interstitials, respectively. Varying reaction conditions allowed for the control of the size and structure of these different morphologies which will be useful for exploring possible energy applications such as electrode material in dye-sensitized solar cells. A non-hydrolytic coprecipitation method and a solvothermal method were used in collaboration with ligand exchange to synthesize and functionalize ethyl xanthate-capped magnetite (Fe3O4) and 1-dodecyl xanthate-capped magnetite nanoparticles. The inverse spinel crystal phase was determined using XRD. The particle size was analyzed using Dynamic Light Scattering (DLS) providing insight into possible agglomeration issues with sizes ranging from 30 nm to 160 nm. Fourier Transform Infrared Spectroscopy (FT-IR) was used to detect the presence of the xanthate capping agents on the surface of the magnetite nanoparticle core with further confirmation from XRF indicating the presence of sulfur and iron. The bactericidal efficacy of the ethyl xanthate-capped magnetite was investigated against eight bacterial species in the Xanthomonas genus using a plate counting method comparing bacterial colony counts of plates exposed to the nanoparticles against a control.