Engineering Commons^™

Anion Exchange And Bipolar Membranes For Electrochemical Energy Conversion And Storage, Zhongyang Wang

McKelvey School of Engineering Theses & Dissertations

Anion exchange and bipolar membrane fuel cells generate electrical energy directly from chemical fuels and have attracted considerable interests as alternate power sources for large market applications, such as transportation (hydrogen fuel cells) and unmanned vehicles (sodium borohydride fuel cells). Anion exchange membrane (AEM), generally composed of a polymer with covalently tethered ionic groups, is the central component of the fuel cell serving as the electrolyte, conducting hydroxide ions from cathode to anode, where fast ionic conduction is directly related to power output. However, AEMs currently used in fuel cells (H2 fuel cells and sodium borohydride fuel cells) exhibit ion …

Design, Microfabrication And Characterization Of Concentric Gold Nanoring Electrode For Neurochemical Sensing, Haocheng Yin

Doctoral Dissertations

Nanoelectrodes have become widely used in electrochemical sensing in recent decades. When compared to microelectrodes, it has many unique advantages such as high signal to noise ratio, small sample volume requirement, and lower detection limits.

This work reports on the microfabrication and characterization of a gold nanoring electrode (Au NRE) patterned on top of a silicon (Si) micropillar. An NRE of 165  10 nm in width was micropatterned on 4.6  1 µm diameter  17.5  2.5 µm long Si micropillar with an intervening 50 nm thick hafnium oxide insulating layer. Scanning electron microscopy and energy dispersive spectroscopy …

Modification And Optimization Of Conducting Polymer-Modified, Redox-Magnetohydrodynamics (R-Mhd) Pumping For Enhanced And Sustained Microfluidics Applications, Md Foysal Zahid Khan

Graduate Theses and Dissertations

In this work, a novel microfluidic pumping approach, redox-magnetohydrodynamics (R-MHD) has improved by materials and device optimization to use in lab-on-a-chip applications. In R-MHD, magnetic flux (B) and ionic current density (j) interacts to generate body force (FB) in between active electrodes, according to the equation FB = j×B. This unique fluid pumping approach is scalable, tunable, generates flat flow profile, and does not require any channels or valves. Pumping performance, such as speed scales with the ionic current density (j) and duration depends on the total charge (Q). The ionic current density (j) results from the conversion of electronic …

Morphology And Detection Of Corrosion On Stainless Steel Reinforcement In Concrete, Julio J. Saire Yanez

USF Tampa Graduate Theses and Dissertations

Stainless steel (SS) has emerged as an alternative corrosion-resistant reinforcement in concrete instead of the commonly used carbon steel (CS). The biggest advantage of SS is that it takes more time for corrosion to initiate than for CS. An additional benefit from the use of SS in concrete may be derived from the period after the corrosion started until the concrete structure reaches a limit state. This period is called corrosion propagation stage (CPS) and it has been hardly studied in SS reinforced structures. The duration of this period could be related, among other factors, to the morphology of corrosion …

Surface Immobilization Of Terpyridine Compounds, Elizabeth Hallett

Chemical Engineering Undergraduate Honors Theses

The deoxydehydration (DODH) of polyols to alkenes is a promising method of producing high-value chemical feedstocks from biomass-derived materials. Current catalytic systems for DODH require the use of costly reducing agents that generate stoichiometric amounts of chemical waste. Immobilizing catalysts on electrode surfaces using chemical linking groups eliminates the need for sacrificial reductants. In this work, glassy carbon electrodes were modified with 4’-(3,4-dihydroxyphenyl)-2,2’:6’,2’’-terpyridine to investigate o-benzoquinone as a potential linking group for DODH, and possibly for other reactions. Previous studies involving electrodes modified with quinone-containing compounds have primarily been focused on catalyzing the oxidation of NADH; the nature or …

An Experimental And Numerical Investigation Of Flow Accelerated Flibe Corrosion, David B. Weitzel

Nuclear Engineering ETDs

Renewed interest in molten salt reactor technology has brought to light the need for a better understanding of FLiBe corrosion. To this end a flowing FLiBe corrosion test loop was designed to test the flow effects of FLiBe corrosion. The loop consists of a pump, melt tank, and stainless-steel tubing assembly that heats the molten salt to high temperatures and circulates it over test specimens. The experiment has been constructed and has completed initial shakedown testing.

To support the flowing FLiBe experiment, a numerical corrosion model that couples FLiBe electrochemistry, solid metal diffusion, and mass transport was implemented. The model …

Engineering Of Earth-Abundant Electrochemical Catalysts, Dylan D. Rodene

Theses and Dissertations

Alternative energy research into hydrogen production via water electrolysis addresses environmental and sustainability concerns associated with fossil fuel use. Renewable-powered electrolyzers are foreseen to produce hydrogen if energy and cost requirements are achieved. Electrocatalysts reduce the energy requirements of operating electrolyzers by lowering the reaction kinetics at the electrodes. Platinum group metals (PGMs) tend to be utilized as electrocatalysts but are not readily available and are expensive. Ni_1-xMo_x alloys, as low-cost and earth-abundant transition metal nanoparticles (NPs), are emerging as promising electrocatalyst candidates to replace expensive PGM catalysts in alkaline media. Pure-phase cubic and hexagonal Ni_{1-x …}

Electrochemical Separation Of Multivalent Species On A Liquid Bismuth Cathode In Licl-Kcl Eutectic For Used Nuclear Fuel Reprocessing, Michael Woods

Theses and Dissertations

The presence of group I/II fission products (Cs-137, Sr-90, and Ba-137) within molten salt nuclear processes degrades operational efficiencies by contributing to increased radiation levels in the case of material handling processes or to loss of criticality in the case of a reactor. While methods such as zone freezing and ion exchange have been proven for the separation of these fission products in LiCl-KCl salts, they require extra equipment and processing steps. Addition of a liquid metal electrode to molten salt media, such as the electrorefiner of a pyroprocessing scheme or the salt cleaning stage of a molten salt fast …

Novel Cathode Framework, Effective Electrolyte Modification, And Electrode Structural Modification Of High Performance Lithium Sulfur Batteries, Wenduo Zeng

Wayne State University Dissertations

Firstly, TiN nanotube arrays have been investigated as an effective skeleton in the cathode of lithium-sulfur batteries. A series of TiN nanotubes with various diameter and length have been synthesized and tested. Moreover, graphene nanoplatelets have been utilized as a structural anchor to support the TiN nanotubes, and the synergetic effect of composite material and its enhancement on Li-S battery electrochemical performance and cycling stability have been studied. Secondly, the improvement of electrode structural design has been evaluated for their effectiveness by using an in-situ characterization method with other electrochemical characterization. Lastly, the facile method of using transition metal cations …

Chronoamperometry Analysis Of Sweat Sensor Technology, Evan Fritz

Williams Honors College, Honors Research Projects

Due to the demand for in-situ electrolyte sodium sensors, prototype sensors have been produced to create a product for athletes and marathoners to monitor hydration levels. These senors address a desire in the marketplace for athletic monitoring for overall athlete wellness and performance. Sweat sensor samples were created using Multi-walled Carbon Nanotubes functionalized on a Nylon-6 fiber mat using cyclo-oligomeric Calixarene. This production process produces sensors capable of detecting sodium ion concentration present in human sweat in presence of an electric current. Chronoamperometry analysis is used in this manner to determine the functionality of the sensors. Much of the research …