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Thesis (Ph. D.)--University of North Texas, Dec., 2008. / Title from title page display. Includes bibliographical references.

Lack of potable water is one of the major challenges that the world faces currently and the effects of this are mainly experienced by people in developing countries. This has therefore propelled research in advanced oxidation technologies AOTs to improve the current water treatment methods using cost effective, non toxic and efficient treatment methods. Hence, in this study the sol-gel synthesis method was used to prepare TiO2 nanoparticles that were photocatalytically active under UV and visible solar light as well as possessing antibacterial properties. Silver and nitrogen doping was carried out to extend the optical absorption of TiO2. For easy removal and reuse of the photocatalyst the nanoparticles were immobilized on chitosan and poly (vinyl-alcohol-co-ethylene) using the electrospining technique. The synthesized nanomaterials were characterized by FTIR, XRD, SEM/EDS, TEM, DRS, and TGA. FTIR and EDS analysis confirmed the formation and composition of TiO2 nanopowders for the doped and undoped nanoparticles. XRD analysis showed that the anatase phase was the dominant crystalline phase of the synthesized nanopowders. SEM and TEM respectively illustrated the distribution and size of the electrospun nanofibers and the nanoparticles of TiO2. DRS results showed that there was a significant shift in the absorption band edge and wavelength of Ag-TiO2 to 397 nm, followed by N-TiO2 at 396 nm compared to the commercial titania which was at 359 nm. The photocatalytic activities and antibacterial properties of these materials were tested on methylene blue dye and E.coli microorganism respectively. Ag-TiO2 immobilized on nanofibers of chitosan and PVAE had the highest photocatalytic activity compared to N-TiO2. Similar results were observed when the biocide properties of these materials were tested on E. coli.

This thesis reports on the structural and optical properties of laser surface structured Co nanocylinders-Al2O3 cermets on flexible Aluminium substrate for enhanced solar selective absorbers applications. More accurately, the laser surface nano-structured cermet solar absorbers developed consists of oriented metallic nano-cylinders embedded in porous refractory oxide host matrix. Relatively to the 6 existing primary configurations of selective solar absorbers, the investigated nano-composite can be considered as an additional one. This later, which could be classified between textured surfaces and cermet composites consists of non-percolated aligned tubular metallic regions (nanowires) embedded in an oxide host matrix. The methods that are commonly used to produce such nanowires in porous host matrices include electrodeposition into nanometer wide porous material/template. Molecular sieves, track-etched polymer membranes and porous anodic alumina are examples of some of this family of porous materials. The electrodeposition method has attracted much attention because the pore density of the nanowires is high, with controllable diameters in addition to the pores uniformity. In this particular study, the solar selective absorber coating designed consists of Co nanocylinders embedded into nanoporous alumina template produced by standard electrodeposition and thereafter submitted to femtosecond laser surface structuring. While their structural and chemical properties were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and atomic force microscopy, their optical characteristics were investigated by specular & diffuse reflectance. The optimized samples exhibit an elevated optical absorptance α(λ) above 98% and an emittance ε(λ) ~0.03 in the spectral range of 200-1100nm. This set of values was suggested to be related to several surface and volume phenomena such as light trapping, plasmon surface effect as well as angular dependence of light reflection induced by the ultrafast laser multi-scale structuring. The thermal stability of laser surface structured Co nanocylinders-Al2O3 cermets on flexible Aluminium substrate was investigated at temperatures of 200–600 °C. / Physics / Ph. D. (Physics)

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed October 13, 2009). PDF text: 261 p. : ill. (some col.) ; 5 Mb. UMI publication number: AAT 3359063. Includes bibliographical references. Also available in microfilm and microfiche formats.

Includes bibliographical references (p. 193-206).

Thesis (Ph. D.)--University of North Texas, Dec., 2009. / Title from title page display. Includes bibliographical references.

Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Engineering, 2009. / "August, 2009." Title from electronic dissertation title page (viewed 9/23/2009) Advisor, Sadhan C. Jana; Committee members, Avraam I. Isayev, James L. White, George G. Chase, Shing-Chung Josh Wong; Department Chair, Sadhan C. Jana; Dean of the College, Stephen Z. D. Cheng; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Nanohybrid materials have been prepared and examined for their electrocatalytic activity. The nanocomposites have been prepared from carbon nanomaterials (multiwalled carbon nanotubes (MWCNTs) and graphene nanosheets), cadmium selenide quantum dots and metallophthalocyanines (MPcs). The MPcs used in this work are cobalt tetraamino-phthalocyanine (CoTAPc) and tetra (4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninatocobalt (II)) (CoPyPc). Their activity has also been explored in different forms; polymeric MPcs, iodine doped MPcs and covalently linked MPcs. The premixed drop-dry, sequential drop-dry and electropolymerisation electrode modification techniques were used to prepare nanocomposite catalysts on the glassy carbon electrode (GCE) surface. The sequential drop dry technique for MPc and MWCNTs gave better catalytic responses in terms of limit of detection, catalytic and electron transfer rate constants relative to the premixed. MWCNTs and CdSe-QDs have been used as intercalating agents to reduce restacking of graphene nanosheets during nanocomposite preparation. Voltammetry, chronoamperometry, scanning electrochemical microscopy and electrochemical impedance spectroscopy methods are used for electrochemical characterization modified GCE. X-ray photoelectron spectroscopy, X-ray diffractometry, transmission electron microscopy, scanning electron microscopy, infra-red spectroscopy, Raman spectroscopy were used to explore surface functionalities, morphology and topography of the nanocomposites. Electrocatalytic activity and possible applications of the modified electrodes were tested using oxygen reduction reaction, l-cysteine oxidation and paraquat reduction. Activity of nanocomposites was found superior over individual nanomaterials in these applications.