UCLA

Noble metals are the most sought after elements for catalysis because of their versatility, activity, and recyclability for a variety of applications; however they are limited as a resource and expensive. Noble metal nanoparticles offer a solution for use in catalysis because their high surface area to volume ratio maximizes their available surface sites while minimizing the amount of metal used. Additionally, particularly exposed facets of nanoparticles can increase surface energies for superior catalytic activity and induce novel electronic/physical properties. In the first chapter of my thesis, I synthesized palladium, platinum, and semiconductor titania nanoparticles through a biomimetic approach by using peptides to preferentially bind to and expose particular crystal facets of nanoparticles. Using a combinatorial approach called biopanning to find highly selective surface energy modifiers for particular facets of materials gave insight to unique binding motifs for materials as well as induced morphology controlled nanoparticles at ambient conditions. There are limitless combinations of solvents, capping agents, and inorganic precursors for inorganic nanoparticle synthesis. Understanding these systems in terms of more global trends would circumvent the current colossal approach of empirically screening systems. To do this, considering the inorganic-organic interfacial relationship is key. In the second chapter, I report unique aryl small molecules which preferentially bind to palladium surfaces through electrostatic potentials and epitaxial binding in nanoparticle synthesis. These results offer an understanding to the dynamic binding relationship between capping agents and nanoparticle surfaces. Lastly, I report on the synthesis of gold-palladium nanoparticles and their activity for the benzyl alcohol oxidation reaction. It was found that the (100) facets of gold-palladium were more catalytically active than the (111) surface. Details of the nanoparticle shape, size, and activity add to the understanding how this material behaves at the atomic level and will help to impact future advances in this field of catalysis. The syntheses described here are important because they are environmentally friendly, they offer information about the binding mechanisms at the organic-inorganic interface of the systems, and give insight to catalytic behavior. All of this work is necessary to further exploit nanoparticle synthesis, assembly and provide the precise engineering of nanostructured materials.