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Wet-chemistry synthesis and characterization of layered nanomaterials with tailored morphology
Metel, Sonia
This PhD Thesis addresses a comprehensive study on the application of wet-chemistry methods to the preparation of layered nanostructured materials; namely 2-dimensional Mg-Al and Ni-Fe layered double hydroxides and 1-dimensional layered amine-templated gallium chalcogenides. The size and the shape of the obtained materials were tailored by suitably choosing the reaction conditions and were subsequently tested in selected applications. The wet-chemistry techniques used in this Thesis relied on the versatility of commonly used approaches, such as hydrothermal and colloidal processes, with simple modifications of the reaction and post-treatment conditions, which led to the formation of nanoparticles with defined morphology and composition. Mg-Al layered double hydroxides were produced in the form of platelets with two different size ranges: 20-250 nm and 2-3 μm. The flakes with diameter below 50 nm were tested as delivery agents, while the bigger flakes (2-3 μm), in their exfoliated form, are proposed as catalysts. Also, ion-exchange was carried out to minimize the interlayer interactions and facilitate their further exfoliation. On the other hand, Ni-Fe layered double hydroxides in the form of flower-like particles and platelet-like hexagons with high crystallinity were synthesized by the use of different capping agents. Both nanomaterials were tested as electrocatalysts in water splitting reaction showing promising results. Finally, amine-templated gallium chalcogenide (sulfur and selenium) nanotubes were prepared by a heating-up method. Both nanomaterials presented a hollow tubular structure with lengths up to 500 nm and 2 μm for sulfur and selenium derivative, respectively. The long-chain amines acted as a template to produce a structure composed of alternating layers of amines and polymeric gallium chalcogenide. Preliminary tests of these compounds as active materials for lithium ion batteries anodes showed their potential in energy storage. In summary, the versatility of wet-chemistry methods was explored to synthesize several layered nanomaterials with a controlled morphology. The obtained nanostructures showed promising behaviour in biological application (Mg-Al layered double hydroxide), water splitting (Ni-Fe layered double hydroxide) and energy storage (AtGaS/Se nanotubes).
Keyword(s): wet-chemistry; layered nanomaterials
Publication Date:
Type: Doctoral thesis
Peer-Reviewed: Yes
Institution: Trinity College Dublin
Publisher(s): Trinity College Dublin. School of Chemistry. Discipline of Chemistry
Supervisor(s): Nicolosi, Valeria
First Indexed: 2017-07-26 05:42:11 Last Updated: 2017-08-03 06:03:02