Physical Sciences and Mathematics Commons^™

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 …

Exploring The Potential Of Ionothermal Syntheses For High-Performance Lithium-Ion Battery Anode Materials, Runming Tao

Doctoral Dissertations

Renewable energy storage systems are regarded as the solution to the environmental and energy crises caused by the burning of fossil fuels in vehicles. Unfortunately, owning to the limits to the electrochemical performance of the current anode materials, lithium-ion batteries [LIBs] are still lacking strength in the charging rate-capability and thereby cannot fulfill future application requirements in electrical vehicles [EVs].

Particularly, graphite with a high theoretical specific capacity of 372 mAh/g is unsuitable for EVs due to the safety concerns of passivating solid-electrolyte interphase [SEI] resulted from the low operation potential of 0.1 V versus Li/Li⁺. The other …

Using Applied Field, Pressure, And Light To Control Magnetic States Of Materials, Amanda J. Clune

Doctoral Dissertations

Due to their low energy scales, flexible architectures, and unique exchange pathways, molecule-based multiferroics host a number of unique properties and phase transitions under external stimuli. In this dissertation, we reveal the magnetic- and pressure-driven transitions in [(CH₃)₂NH₂]Mn(HCOO)₃ and (NH₄)₂[FeCl₅(H₂O)], present a detailed investigation of these materials away from standard equilibrium phases, and develop rich two- and three-dimensional phase diagrams.

The first platform for exploring phase transitions is [(CH₃)₂NH₂]Mn(HCOO)₃. This type-I multiferroic contains Mn centers linked by …

Characterization Techniques And Cation Exchange Membrane For Non-Aqueous Redox Flow Battery, Kun Lou

Doctoral Dissertations

The motivation of this work comes from one of the major problems of emerging non-aqueous flow battery (NAFB) that a separator or membrane which facilitates conductivity and blocks redox species crossover does not exist. Although many aspects of principles can be mirrored from mature fuel cell and aqueous flow battery, it is found that some well-defined membrane properties in aqueous systems such as swelling, transport and interactions are different in non-aqueous solvents to some extent. However, the approach of this work does follow the way perfluorosulfonate ion exchange membrane (PFSA) facilitated development of fuel cell and aqueous flow battery in …

Synthesis, Characterization, And Applications Of Nucleobase-Functionalized Conjugated Polymers, Sina Sabury

Doctoral Dissertations

Understanding the effect of the functional groups at the terminus of the side chains is important for developing conjugated polymers through side chain engineering. Nucleobases, which are known for their multi-functionality, have not been deeply studied as functionality in conjugated polymers due to synthetic challenges. The overarching goal of my dissertation is to design, synthesize, characterize conjugated polymers bearing nucleobase functionality in their side chains and demonstrate their utility in various applications. Stille cross-coupling and direct arylation polymerization are used to synthesize adenine- and thymine-containing conjugated polymers. Monomer design requirements for successful polymerization are studied and conditions that optimize polymerization …

Application Of Titrations For Verification Of Small Molecule Interaction In Relation To Amidoximated Fibers For Uranium Extraction From Seawater, Kc Michael Mote

Masters Theses

Nuclear energy is a promising substitute for fossil fuels due to possessing low carbon emissions and providing scalable base-load power. However, one major drawback of using nuclear fuel as an energy source is that it needs a steady source of uranium. While the most economical method of obtaining uranium is through conventional terrestrial mining of the ore uranite, mining uranium ores is both harmful to the environment and limited by the terrestrial uranium supply, which is estimated at only 100 more years. However, more than 1000× more uranium is dissolved in seawater than is reasonably inferred and assured in terrestrial …