ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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Description
Due to the potential synergistic properties from combining inorganic and organic moieties, inorganic/organic hybrids materials have recently attracted great attention. These hybrids are critical components in coating and nanocomposite additive technologies and have potential for future application in catalysis, energy production or storage, environmental remediation, electronic, and sensing technologies. Most of these hybrids utilize low dimensional metal oxides as a key ingredient for the inorganic part. Generally, clay materials are used as inorganic components, however, the use of low dimensional transition metal oxides may provide additional properties not possible with clays. Despite their potential, few methods are known for the use of low dimensional transition metal oxides in the construction of inorganic/organic hybrid materials.Herein, new synthetic routes to produce hybrid materials from low dimensional early transition metal oxides are presented. Included in this thesis is a report on a destructive, chemical exfoliation method designed specifically to exploit the Brønsted acidity of hydrated early transition metal oxides. The method takes advantage of (1) the simple acid-base reaction principle applied to strong two-dimensional Brønsted solid acids and mildly basic, high-polarity organic solvents, (2) the electrostatic repulsion among exfoliated nanosheets, and (3) the high polarity of the organic solvent to stabilize the macroanionic metal oxide nanosheets in the solvent medium. This exfoliation route was applied to tungstite (WO3∙H2O) and vanadium phosphate hydrate (VOPO4∙H2O) to produce stable dispersions of metal oxide nanosheets. The nanosheets were then functionalized by adduct formation or silane surface modification. Both functionalization methods resulted in materials with unique properties, which demonstrates the versatility of the new exfoliation methods in preparing novel hybrid materials.
Further extension of the method to aqueous systems allowed discovery of a new synthetic method for electrically-conducting polyaniline-polyoxometalate hybrid materials. Namely, destructive dissolution of MoO2(HPO4)(H2O) in water produces protons and Strandberg-type phosphomolybdate clusters, and in the presence of aniline and an oxidizing agent, the clusters self-assemble with protonated anilines and selectively form polyaniline-phosphomolybdate hybrids on various types of surfaces through in situ oxidative chemical polymerization. New conductive nanocomposite materials were produced by selectively coating the surface of silica nanoparticles.
ContributorsCiota, David (Author) / Seo, Dong-Kyun (Thesis advisor) / Trovitch, Ryan (Committee member) / Birkel, Christina (Committee member) / Arizona State University (Publisher)
Created2022
Description
Pure metal clusters serve as model systems by providing an avenue for the study of fundamental phenomena, specifically the interaction between light and matter. Bulk metal materials are known to display defining characteristics, namely thermal conductivity, electrical conductivity, and luster, which provide a quantifiable measure of their metallicity. These properties are all due to the electron delocalization throughout the metal. Nanoscale materials lack the ability to measure these properties, leading to the need for a manner of quantifying the metallic character at the nanoscale size regime.Excited state lifetimes vary for semiconducting and metallic systems, specifically metals relax to a ground state at a faster rate than semiconducting materials. Aluminum clusters have received decades of attention regarding their metallicity. Moreover, Al clusters have been debated to fit into the jellium model. The jellium model seeks to describe a cluster as a “superatom” where all electrons are delocalized around the positively charged metal center, like that of an atom. With three valence electrons, jellium shell closings can be met if the electrons involved in cluster bonding varies. This variance leads to a localization of electrons for instances in which all three electrons do not contribute to bonding. Localized electrons aren’t characteristic of the jellium model or metals more broadly. Tracking the excited state lifetimes of Al clusters produced through laser ablation seeks to uncover the onset of metallic character. Femtosecond pump-probe spectroscopy coupled with time-of-flight mass spectrometry has resolved the time dynamics for atomically precise Al clusters ranging in size from 1-43 atoms. At a size greater than 9 atoms, it’s identified that Al clusters show metallic character. This finding is supported by previous literature results and the fact that, above 9 atoms, Al cluster excited state lifetimes match that of the bulk scale Al excited state lifetime of ~300 fs.
ContributorsJarman, Carter Korey (Author) / Sayres, Scott G (Thesis advisor) / Birkel, Christina (Committee member) / Chizmeshya, Andrew (Committee member) / Arizona State University (Publisher)
Created2024