Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 271-303).

Five commercial metal oxide nanoparticles (CuO, SiO2, Fe2O3, TiO2 and Al2O3) have been individually screened for mercury removal in a batch reactor under bicarbonate buffered and non-buffered aqueous solutions (DI water). Copper oxide was then selected for surface modification to enhance mercury removal. The surfaces of both laboratory prepared and commercially available copper oxide nanoparticles were treated with 1-octanethiol to produce copper sulfide and/or copper alkanethiol nanoparticles. The resulting particles were characterized using X-Ray Fluorescence(XRF), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The novel nanoparticles demonstrated very high mercury removal (> 99%) from both the buffered and non-buffered aqueous solutions.

Thesis advisor: Dunwei Wang / Semiconductor devices offer promise for efficient conversion of sunlight into other useful forms of energy, in either photovoltaic or photoelectrochemical cell configurations to produce electrical power or chemical energy, respectively. This dissertation examines ionic and electronic phenomena in some candidate semiconductors and seeks to understand their implications toward solar energy conversion applications. First, copper sulfide (Cu₂S) was examined as a candidate photovoltaic material. It was discovered that its unique property of cation diffusion allows the room-temperature synthesis of vertically-aligned nanowire arrays, a morphology which facilitates study of the diffusion processes. This diffusivity was found to induce hysteresis in the electronic behavior, leading to the phenomena of resistive switching and negative differential resistance. The Cu₂S were then demonstrated as morphological templates for solid-state conversion into different types of heterostructures, including segmented and rod-in-tube morphologies. Near-complete conversion to ZnS, enabled by the out-diffusion of Cu back into the substrate, was also achieved. While the ion diffusion property likely hinders the reliability of Cu₂S in photovoltaic applications, it was shown to enable useful electronic and ionic behaviors. Secondly, iron oxide (Fe₂O₃, hematite) was examined as a photoanode for photoelectrochemical water splitting. Its energetic limitations toward the water electrolysis reactions were addressed using two approaches aimed at achieving greater photovoltages and thereby improved water splitting efficiencies. In the first, a built-in n-p junction produced an internal field to drive charge separation and generate photovoltage. In the second, Fe₂O₃ was deposited onto a smaller band gap material, silicon, to form a device capable of producing enhanced total photovoltage by a dual-absorber Z-scheme mechanism. Both approaches resulted in a cathodic shift of the photocurrent onset potential, signifying enhanced power output and progress toward the unassisted photoelectrolysis of water. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1928. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed October 21, 2009) Includes bibliographical references (p. 103).

<p> Two methods for preparing semiconductor grade copper sulfide films, to be used in low cost thin film solar cells,have been investigated. The sulfurization method involves the controlled chemical conversion of copper films into the desired copper sulfide phase. The other method of evaporating Cu2S pellets is more adaptable for an all evaporated thin film solar cell. The copper sulfide films obtained by these methods were characterized using x-rays, cathodoluminescence, electrical and optical methods. The use of optical method in monitoring the stoichiometry of thin copper sulfide films has been illustrated. The photovoltaic properties of thin copper sulfide films obtained by these methods, were also investigated using Cu2S - Si heterojunctions. The behaviour of these junctions indicates that 900 Ȧ thick copper sulfide film is required for optimum photovoltaic conversion. This result may be of some importance in Cu2S - CdS solar cells in further reducing their thickness. Cu2S - Si heterojunctions can also be used to monitor the properties of copper sulfide, as silicon is a well characterized substrate.</p> / Thesis / Master of Science (MSc)

No description available.

Thesis advisor: Dunwei Wang / In this work, we present our findings regarding the low-temperature, solid-state conversion of Cu₂S nanowires to Cu₂S/Cu₅FeS₄ rod-in-tube structures, Cu₂S/ZnS segmented nanowires, and a full conversion of Cu₂S nanowires to ZnS nanowires. These conversion reactions occur at temperatures as low as 105 degrees Celsius, a much lower temperature than those required for reported solid-state reactions. The key feature of the Cu₂S nanowires that enables such low conversion temperatures is the high ionic diffusivity of the Cu⁺ within a stable S sublattice. The second portion of this work will focus on the oxide-stabilization and utilization of TiSi₂ nanonets as a lithium-ion battery anode. This nanostructure, first synthesized in our lab, was previously demonstrated to possess a lithium storage capacity when cycled against a metallic Li electrode. However, with subsequent lithiation and delithiation cycles, the TiSi₂ nanonet structure was found to be unstable. By allowing a thin oxide layer to form on the surface of the nanonet, we were able to improve the capacity retention of the nanonets in a lithium-ion half-cell; 89.8% of the capacity of the oxide-coated TiSi₂ was retained after 300 cycles compared to 62.3% of the capacity of as-synthesized TiSi₂ nanonets after 300 cycles. The layered structure of C49 TiSi₂ exhibited in the nanonets allows for a specific capacity greater than 700 mAh g(-1), and the high electrical conductivity of the material in conjunction with the layered structure confer the ability to cycle the anode at rates of up to 6C, i.e., 10 minute charge and discharge cycles, while still maintaining more than 75% of the capacity at 1C, i.e., 1 hour charge and discharge cycles. / Thesis (MS) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

In this thesis, a facile methodology for the synthesis of CdS and PbS particles using novel thiobisphthalimide (D1) and dithiobisphthalimide (D2) organic sulfur precursors is proposed. A slightly different approach was followed for the synthesis of CuS particles. The effect on the size and morphology of the particles of a variety of reaction parameters such as the nature of sulfur precursor, the reducing agent concentration, the metal-to-sulfur ratio and the reaction temperature was investigated. The phase and composition identifications of the CdS and PbS particles were done by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques were employed to determine the morphologies of the particles. The optical properties of the CdS, PbS and CuS particles were examined by UV-Vis and fluorescence spectroscopy techniques. The phase identification results showed that pure cubic CdS and PbS, and hexagonal CuS particles were successfully synthesized with both D1 and D2 precursors. The synthesized CdS and PbS particles possess various morphologies depending on the precursor type and the reaction parameters mentioned previously. Control of the size of the PbS particles in one dimension in a quantum confinement regime was possible, whereas the CdS particles exhibited faster growth and 3D morphologies. The CuS particles, on the other hand, were produced with high monodispersity in a surfactantless environment.

No description available.

No description available.