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Interfacial Chemistry at the Surfaces of Engineered and Natural Nanomaterials
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The central theme of my research seeks to understand the interfacial chemistry of engineered and natural nanomaterials. Manipulation of the surface chemistry of nanostructures is an important tool in tuning their properties for various applications, given that these properties are greatly influenced by the high abundance of defects and dangling bonds on the surface. When an ad-atom, molecule, or periodic solid interacts with the surface of a material, the interaction can be classified as either physisorptive or chemisorptive. Herein, I present three disparate areas of research, which explore interfacial interactions at nanostructured surfaces. Emphasis on the chemisorption and physisorption on engineered nanomaterials is provided in the first and third projects. The first project illustrates that graphene oxide is partially reduced when used as a substrate for the atomic layer deposition (ALD) of amorphous HfOv2. Understanding the interfacial chemistry between graphene oxide and HfOv2 provides new knowledge on designing graphene-based field effect transistors and semiconductor heterostructures for catalysis. In the third project, a novel ex situ doping technique for modulating the metal—insulator transition (TvMIT) of VOv2 has been developed. Initial deposition of the molecular boron precursor 2-allyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane on the surface of VOv2 nanowires allows for the subsequent incorporation of B atoms in the tetrahedral interstitial sites of VOv2 upon rapid thermal annealing, which results in the stabilization of the rutile phase in greater proximity to room temperature. The diffusive annealing process can be tuned to program the TvMIT of VOv2 for applications such as thermochromic fenestration and the design of memory devices. The second project is focused on natural nanomaterials, wherein the interactions of Ag-Au bimetallic alloy nanoparticles in aquatic media have been investigated. The growth of these alloy nanoparticles is mediated by dissolved organic matter (DOMs) such as fulvic and humic acids, with or without photoillumination from natural sunlight. In the absence of natural sunlight, Ag- and Au-ions are first complexed with Lewis basic groups (carbonyls, carboxyls, thiols) on the DOM; subsequently, alloy formation is facilitated by galvanic replacement. Under visible light irradiation, Ag, Au, and Ag-Au bimetallic alloy nanocrystals are grown via a plasmon-induced mechanism. The study of the interfacial chemistry at the surfaces of these nanomaterials paves way for the rational design of various architectures which can be used for various applications such as catalysis, environmental remediation, and thermochromic fenestration.
atomic layer deposition
Alivio, Theodore Emmanuel Gatmaitan (2019). Interfacial Chemistry at the Surfaces of Engineered and Natural Nanomaterials. Doctoral dissertation, Texas A & M University. Available electronically from