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Ultrasound-Driven Fabrication Of Nanosized High-Entropy Materials For Heterogeneous Catalysis, Francis Uchenna Okejiri

Doctoral Dissertations

High-entropy materials (HEMs) have emerged as a new class of multi-principal-element materials with great technological prospects. As a unique class of concentrated solid-solution materials, HEMs, formed on the premise of incorporating five or more principal elements into a single crystalline phase, provide an excellent opportunity to access superior catalytic materials ‘hiding’ in the unexplored central regions of a multicomponent phase space of higher orders.

However, the fabrication of HEMs is energy-intensive, typically requiring extreme temperatures and/or pressures under which agglomeration of particles occurs with a commensurate decrease in surface area. For most catalytic applications, non-agglomerated particles with high surface areas …

Rational Design Of Non-Noble-Metal Heterogeneous Catalysts For The Production Of Renewable Fuels And Valuable Chemicals Via A Combined Experimental And Theoretical Approach, Yang He

Doctoral Dissertations

The aim of this study was to utilize a combination of quantum chemical modeling calculation and state of the art experimental techniques to develop inexpensive non-noble metal catalysts for contemporary reactions. Specific focus was placed on understanding how to systematically tune the surface chemical reactivity as a function of the compositional constitution within the solids, e.g. transition metal + post-transition metal and transition metal + p-block element materials. The efforts upon developing fundamental understandings on surface chemistry drive the discovery of catalysts that exhibit appropriate reactivity to enable selectively activating C–C, C–O, and C–H bonds within linear and aromatic unsaturated …

Structural Modifications And Their Effects On The Catalytic Behavior Of Metal Surfaces And Organometallic Complexes: Theoretical Studies Of Oxygen Adsorption On Silver Surfaces And Aziridination Catalysis By Iron-Tetracarbene Complexes, Sara Beth Isbill

Doctoral Dissertations

Great interest exists in efficient synthesis of epoxides and aziridines, molecules containing three-membered rings with oxygen and nitrogen atoms, respectively, due to their use in the chemical and pharmaceutical industries. Epoxides, such as ethylene oxide, can be partially oxidized to form ethylene glycol, a feedstock in many consumer products. Typically, ethylene oxide is made over a silver surface; however, there remain many questions as to the structure of the active catalyst. In this work, the interaction of atomic oxygen with two facets of silver has been investigated with molecular dynamics simulations and density functional theory (DFT) calculations. These studies revealed …

Synthesis And Characterization Of Functionalized Nanomaterials: Heterogeneous Palladium Catalyst And Lithium-Doped Graphene Oxide, Benjamin E Estes

Doctoral Dissertations

As the Earth's population increases and natural resources decrease in supply, the development of new methods for energy storage and the efficient production of industrial chemicals becomes ever more important to humanity. The development of new nanomaterials may offer technological advances in the fields of sustainable energy production and storage, chemical production, medicine, and many others. The emerging field of nanoscience blends chemistry, physics, and engineering to create new materials that take advantage of properties found only on the nanoscale.

In this work, mesoporous silica spheres are used as a support for nanoparticles of palladium. This nanomaterial is shown to …

Homogeneous And Heterogeneous Approaches To 1,2,4-Triazine-Accelerated Copper-Catalyzed Azide-Alkyne Cycloadditions, Ashleigh Lauren Prince

Doctoral Dissertations

Over the last decade, the domain of click chemistry has grown exponentially and has significantly impacted the fields of organic synthesis, medicinal chemistry, molecular biology, and materials science. The ideal model of a click reaction has become the copper-catalyzed azide-alkyne cycloaddition (CuAAC). Inherent limitations of CuAAC, including high temperatures, long reaction times, and difficult purifications, have been minimized by the development of nitrogen-based ligands. Herein, we present a novel application of 1,2,4-triazines by investigating their use as accelerants for CuAAC.

A diverse library of 1,2,4-triazines were synthesized in order to examine the molecular determinants of their catalytic activity. These ligands …