Physical Sciences and Mathematics Commons^™

Triphenylamine-, Porphyrin- And Fullerene-Based Derivatives For Photovoltaic And Other Applications, Danisha Marie Rivera Nazario

Open Access Theses & Dissertations

Proper collection of charges at the electrodes is an important process in organic solar cells. Interfacial layers between the electrodes and the photoactive layer have been design to improve charge collection and ohmic contacts. The most studied interfacial layer between the anode and the photoactive layer is the negatively charged polymer poly(3,4-ethylendioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), that possesses good hole transporting ability. However, inhomogeneities at the surface of the electrode after deposition of the polymer lower the stability and performance of the OPV devices. Triphenylamine (TPA) derivatives have received increased attention in the organic solar cells (OSCs) field because of their favorable light …

Elucidating The Electronic Structure Of Multiple Bonded Systems: Synthesis And Characterization Of Bimetallic Tungsten And Ruthenium Complexes, Karen Ventura

Open Access Theses & Dissertations

The following study is presented in two sections. In the first section variable-temperature magnetic and structural data of two pairs of diruthenium isomers (having an idealized D4h symmetry), one pair having axial ligands and the formula Ru2(DArF)4Cl (where DArF is the anion of a diarylformamidine isomer, and Ar = p-anisyl or m-anisyl) and the other one being essentially identical but devoid of axial ligands and having the formula [Ru2(DArF)4]BF4, show that the axial ligands have a significant effect on the electronic structure of the diruthenium core. Variable-temperature crystallographic and magnetic data as well as density functional theory (DFT) calculations unequivocally …

Plasma Treated Mesoporous Tio2 Thin Films For Energy Storage Applications, Allen D. Reed

Theses and Dissertations--Chemistry

Mesoporous TiO₂ films treated with N₂/argon plasma or H₂ plasma were studied for use in photoelectrochemical water splitting and electrochemical supercapacitors, respectively. Cubic-ordered mesoporous thin films were prepared by a templated sol-gel method. UV-Vis absorbance spectra indicated that nitrogen plasma treatment significantly reduced the band gap of the TiO₂. XPS analysis showed that nitrogen atoms are incorporated into substitutional sites, rather than interstitial. Photocatalytic activity of nitrogen-doped TiO₂ films was evaluated by chronoamperometry and linear sweep voltammetry. Compared to pristine TiO₂, plasma-treated films showed remarkable photocurrent enhancement (up to 240 times) …

Electrogenerated Chemiluminescence Of Gold Nanoclusters, Mahdi Hesari

Electronic Thesis and Dissertation Repository

A series of monodispersed AuNCs including Au144(SR)60, Au38(SR)24 and Au25(SR)18z (z =1-, 0 and 1+, SR=2-phenylethanethiol) were prepared. All these nanoclusters showed molecule-like optical and electrochemical properties. These two features are essential for an electrogenerated chemiluminescence or electrochemiluminescence (ECL) study. The Au144(SR)60 showed a small HOMO-LUMO gap determined by electrochemistry. No ECL light was seen in the annihilation process, while NIR ECL was observed with tri-n- propylamine (TPrA) (Chapter 2). ECL was highly efficient in the Au38(SR)24/TPrA co- reactant system. This nanocluster also showed ECL emission with benzoyl peroxide (BPO), while no ECL was detected in the annihilation route (Chapter …

Modified-Electrodes For Redox-Magnetohydrodynamic (Mhd) Pumping For Microfluidic Applications, Christena Kayl Nash

Graduate Theses and Dissertations

A new microfluidic pumping and stirring technique was demonstrated for lab-on-a-chip applications. Microfluidics was accomplished via redox-MHD, which takes advantage of a body force (F_B) that is generated when there is a net movement of ions in solution (j) in the presence of a perpendicular magnetic field (B), according to the equation F_B = j×B. In this work the movement of ions in solution was generated using electrodes modified with the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) rather than a redox species in solution, which can interfere with analyte detection and with biological species. …

The Electrochemistry Of Hydrogen Peroxide On Uranium Dioxide And The Modelling Of Used Nuclear Fuel Corrosion Under Permanent Disposal Conditions, Linda Wu

Electronic Thesis and Dissertation Repository

This thesis reports a series of investigations examining the corrosion process of used nuclear fuel under permanent disposal conditions. The motivation of the project is that the safety assessment of deep geological disposal of spent nuclear fuel requires a fundamental understanding of the processes controlling fuel corrosion which could lead to the release of radionuclides to the geosphere from a failed container.

One primary objective of this project was to develop a computational model in order to simulate fuel corrosion under the disposal conditions. A series of simulations based on COMSOL were designed and developed to determine the influence of …

Investigation And Characterization Of Pt-Modified Au Catalysts And Polymer Composites By Electrochemistry, Raman And Surface Enhanced Raman Spectroscopy (Sers), Ranjani Muralidharan

USF Tampa Graduate Theses and Dissertations

This dissertation thesis consists of six chapters. The main focus of this study is the need for understanding the reaction mechanism and intermediates formed on Pt-modified Au surface as anode catalysts in the formic acid fuel cells. Chapter 1 gives an introduction to formic acid and methanol fuel cells, an overview of the current catalysts employed at the anode of the fuel cells, specifically the Pt-modified Au electrodes as potential catalysts and the different deposition methods for preparing this catalytic surface. Information about different electrochemical methods used like cyclic voltammetry and potential step method along with other characterization methods and …

Fabrication And Characterization Of High Surface Area Gold Electrodes, Madhura S. Damle

Theses and Dissertations

High surface area gold electrodes are very good substrates for biosensors, catalysis and drug delivery. Their performance is characterized by good sensitivity, low detection limit and high signal. As a result, extensive research is being carried out in this field using different approaches of fabrication to generate high surface area porous electrodes of different morphology, pore size and structure. The morphology of the electrodes can be changed based on whether the approach involves a template or not, types of metal deposition, method and time of dealloying etc. The deposition of metal can be carried out using various approaches such as …

Anodic Strategies For The Covalent Attachment Of Molecules To Electrodes Through Ethynyl And Vinyl Linkages, Matthew Vincent Sheridan

Graduate College Dissertations and Theses

Substrates with localized, organic radicals have the ability to attack `inert' surfaces to form covalent bonds between the substrate and an atom at the surface. These radicals can be generated in electrochemical experiments with substrates bearing an electroactive moiety. The moiety after oxidation (loss of an electron) or reduction (gain of an electron) generates the active radical. Electron transfer reactions at an electrode surface generate a high population of these radicals, thereby facilitating attachment.

The electrochemical oxidations of compounds containing terminal alkynes and alkenes were found to be effective methods for covalent attachment to glassy carbon, gold, and platinum electrodes. …

Microfluidics Guided By Redox-Magnetohydrodynamics (Mhd) For Lab-On-A-Chip Applications, Vishal Sahore

Graduate Theses and Dissertations

Unique microfluidic control actuated by simply turning off and on microfabricated electrodes in a small-volume system was investigated for lab-on-a-chip applications. This was accomplished using a relatively new pumping technique of redox-magnetohydrodynamics (MHD), which as shown in this dissertation generated the important microfluidic features of flat flow profile and fluid circulation. MHD is driven by the body force, FB = j × B, which is the magnetic part of the Lorentz force equation, and its direction is given by the right hand rule. The ionic current density, j, was generated in an equimolar solution of potassium ferri/ferro cyanide by applying …

Electrochemiluminescence Of Thienyltriazoles, Iridium Complexes, Au25 Clusters And Pbs Nanoparticles, Kalen N. Swanick

Electronic Thesis and Dissertation Repository

Electrogenerated chemiluminescence or electrochemiluminescence (ECL), produces light in the vicinity of a working electrode by the excited species of a luminophore formed via electron transfer between radical cations and anions, which are electrogenerated. In order for the ECL system to be efficient, the radicals must be stable in solution. This can be enhanced by adding co-reactants such as benzoyl peroxide (BPO) and tri-n-propylamine (TPrA) that produce strong oxidizing or reducing radicals upon redox reactions. ECL pairs electrochemical and spectroscopic methods and is a powerful analytical technique that is highly sensitive and selective.

A comprehensive, mechanistic study of ECL …

Nos Oxygenase-Mediated Nitroalkane Catalytic Reduction: Impact On Nos Reaction, Praneeth Ivan Joel Fnu

ETD Archive

Organic nitroalkanes are used in many industries and for a variety of purposes. Their use is expanding and is steadily claiming new territories in our immediate environment. Some nitroalkanes, when they enter the human body, can be harmful as such or can be activated to generate reactive intermediates with known detrimental effects. P450 enzymes are known for metabolizing a variety of drugs and substances including organic nitroalkanes. Nitric oxide synthases (NOS) exhibit some similarities to P450 metalloenzymes and their potential interaction with nitroalkanes as xenobiotics is not well known. The present study investigates the effect of nitroalkanes on the catalytic …

Acid-Base Catalysis In Proton-Coupled Electron Transfer Reactions (Pcet): The Effects Of Brönsted Bases On The Oxidation Of Glutathione And Hydroquinone, Ramos Jonnathan Medina

Theses and Dissertations

This thesis presents the results and discussion of the investigation of the effects of Brönsted bases on the kinetics and thermodynamics of two proton-coupled electron transfer processes: the mediated oxidation of glutathione and the electrochemical oxidation of hydroquinone. Proton-coupled electron transfer (PCET) is the name given to reactions that involve the transfer of electron(s) accompanied by the exchange of proton(s). PCETs are found in many chemical and biological processes, some of current technological relevance such as the oxygen reduction reaction in fuel cells, which involves the transfer of four electrons and four protons (4e-, 4H+); or the splitting of water …

New Approaches To Electroanalysis Of Metals And Pretreatment Of Biological And Environmental Samples, Stefanie Bragg

Doctoral Dissertations

Biological and environmental sample pretreatment followed by electrochemical sensing are the focus of this dissertation. The Advanced Oxidation Process (AOP) treatment using aqueous hydrogen peroxide and UV irradiation with acid deactivation of the enzyme catalase in blood has been developed and optimized. The kinetics of whole blood AOP in a single-cell reactor was studied, and the effect of pH on the AOP process has been investigated. A new method of dry ashing whole blood has been developed and optimized for trace metal analyses. The new method and subsequent metal analyses in the blood samples has been used to confirm results …

Development Of Nano-Scale Featured Materials For Electrode Modification And Solid Supports., Amy Rue

Theses and Dissertations

This work utilized the sol-gel process in two ways. First, macroporous silica thin films were developed using a combination of casting techniques and templating. Macroporsity was introduced to the silica thin films by either doping the silica sol before casting or by ordering the template on a substrate and then casting a sol over it. These techniques were first used to create silica thin films with long microchannel pores (200 nm x 60 µm) from a doped sol with the bacteria, B. Megaterium, as the template for nanomaterial formation. To enable the formation long microchannels, the flexible bacteria chains were …

Studies Toward The Development Of A Microelectrode Array For Detection Of Dopamine Through Redox Cycling, Anupama Aggarwal

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that cycles the reversible redox species between its oxidative states repeatedly on generator and collector electrodes. Two or more individually-addressable microelectrodes located close to each other allow redox cycling to be possible. Electrochemical behavior of a biologically important molecule, dopamine is examined under redox cycling conditions. To our knowledge, this is the first report on detection of physiological concentration of dopamine in presence of up to 100 times excess ascorbate with the use of redox cycling, without the involvement of polymer coating such as Nafion®.

Microfabrication was used to produce different geometries (parallel bands …

Synthesis, Extraction, Dissolution, And Voltammetry Of F-Species In A Room Temperature Ionic Liquid Solvent, Wendy Jacqueline Pemberton

UNLV Theses, Dissertations, Professional Papers, and Capstones

Room temperature ionic liquids (RTILs) are salts that are liquids from as low as -96 °C to up to 100 °C. RTILs are of high interest in many fields of study because of their negligible vapor pressure, high electrochemical stability, high conductivity, and wide electrochemical windows. These diverse solvents have recently been used in organic synthesis, as extraction solvents, and as electrochemical solvents. It is as a direct result of the multifunctional capabilities of these RTIL solvents that they are examined in this work. The ability to probe the chemistry of lanthanides and actinides is based on the unique properties …

Spectroelectrochemistry And Voltammetry Of Metalloporphinones, Florentina Tutunea

Dissertations (1934 -)

Metalloporphinones have been found in a number of enzymes involved in nitrogen metabolism. The emphasis of this research project has been to develop spectroscopic markers in order to identify metal versus porphinone reduction. The carbonyl group in the porphinone has a very strong signal which is quite sensitive to the extent of reduction of the porphinone macrocycle.

The spectral change makes IR an important tool in the process of structure determination of metalloporphyrins because the carbonyl group shift can be correlated with the metal oxidation state. It was observed from previously published studies that a higher metal oxidation state moves …

The Effect Of The Environment On The Corrosion Products And Corrosion Rates On Gas Transmission Pipelines, Brent Sherar

Electronic Thesis and Dissertation Repository

This thesis reports a series of investigations examining external corrosion processes along gas transmission pipelines. TransCanada PipeLines Ltd. (TCPL) has developed six proposed corrosion scenarios to describe external pipeline corrosion, based primarily on corrosion products and corrosion rates (CRs) observed at field sites. The six proposed corrosion scenarios can be divided into two groups: abiotic and biotic. The three abiotic corrosion scenarios are (1) anaerobic corrosion, (2) aerobic corrosion, and (3) anaerobic corrosion turning aerobic; while (4) anaerobic corrosion with microbial effects, (5) aerobic corrosion turning anaerobic with microbial effects, and (6) anaerobic corrosion with microbial effects turning aerobic comprise …

Cetyltrimethylammonium Halide-Coated Electrodes For The Detection Of Dopamine In The Presence Of Interferents, Amber J. Yeary

Browse all Theses and Dissertations

Specially constructed carbon paste electrodes were coated with 10 mM cetyltrimethylammonium halide (CTAX) solutions, bromide and chloride being the counter anions. These surfactant modified electrodes were used to detect the catecholamine neurotransmitter dopamine using cyclic voltammetry. The coated electrodes gave reproducible quasi-reversible behavior for the analyte dopamine over a range of concentrations from 1 mM to 200 mM. When combined in solution with common interferents ascorbic acid (1 mM) and uric acid (300 μM), all cathodic and anodic current peaks maintained resolution at the biological pH of 7.4. When the coating solutions were below the critical micelle concentration (0.5 mM), …

Investigation Of Nanoceria-Modified Platinum-Gold Composite Electrodes For The Electrochemical Reduction Of Oxygen In Alkaline Media, Rahul Hegishte

Electronic Theses and Dissertations

Platinum-gold and nanoceria-modified platinum-gold electrodes were prepared on a platinum surface via electrochemical reduction of solutions of platinum and gold salts in the dispersion of nanoceria. The molar ratios of Pt and Au were varied in both PtAu and PtAu/CeO₂ electrodes while the total concentration of the metals was maintained at 2 x 10⁻³M and the concentration of nanoceria was maintained constant at 5 x 10⁻³M. The electrodes were characterized by their cyclic voltammetry curves in 0.5M sulfuric acid solution. The electrochemically active area of the electrodes was determined using the copper underpotential deposition method. The linear sweep voltammograms of …

Investigation Of Titanium Nitride As Catalyst Support Material And Development Of Durable Electrocatalysts For Proton Exchange Membrane Fuel Cells, Bharat Avasarala

Legacy Theses & Dissertations (2009 - 2024)

The impending energy and climatic crisis makes it imperative for human society to seek non-fossil based alternative sources for our energy needs. Although many alternative energy technologies are currently being developed, fuel cell technology provides energy solutions, which satisfy a wide range of applications. But the current fuel cell technology is far from its target of large scale commercialization mainly because of its high cost and poor durability. Considerable work has been done in reducing the cost but its durability still needs significant improvement. Of the various materials in a PEM fuel cell, the degradation of electrocatalyst affects its durability …

New Electrochemical And Optical Detection Methods For Biological And Environmental Applications, Royce Nicholas Dansby-Sparks

Doctoral Dissertations

Detection of chromium and vanadium is of interest for biomedical and environmental applications. The two metals have narrow limits between being essential and toxic for humans. Ultra-sensitive techniques have been studied to measure Cr and V at low concentrations found in human blood and environmental samples. Bismuth film and mercury-alloy electrodes have been developed as alternatives to traditional Hg-based electrodes for Cr and V detection. While catalytic adsorptive stripping voltammetry (CAdSV) has been used to detect Cr and V, little is known about the process. The mechanisms of CAdSV have been probed to provide a better understanding of its exceptional …

Mechanistic Studies On The Electrochemistry Of Proton Coupled Electron Transfer And The Influence Of Hydrogen Bonding, Timothy Alligrant

Theses and Dissertations

This research has investigated proton-coupled electron transfer (PCET) of quinone/hydroquinone and other simple organic PCET species for the purpose of furthering the knowledge of the thermodynamic and kinetic effects due to reduction and oxidation of such systems. Each of these systems were studied involving the addition of various acid/base chemistries to influence the thermodynamics and kinetics upon electron transfer. It is the expectation that the advancement of the knowledge of acid/base catalysis in electrochemistry gleaned from these studies might be applied in fuel cell research, chemical synthesis, the study of enzymes within biological systems or to simply advance the knowledge …

Synthesis And Development Of Novel Fullerene-Based Structures For Photovoltaics, Electronic Applications And Mri Contrast Agents, Manuel Chaur

All Dissertations

Metallic nitride endohedral metallofullerenes (EMFs) are one of the most interesting types of metallofullerenes due to their high yields and interesting electronic properties. The synthesis of these compounds allows the encapsulation of different metals inside fullerenes making it possible to combine the properties of the metal with those of the fullerene. Their interesting electrochemical and optical features make them potential candidates for several applications such as molecular electronics, biomedical imaging, non-linear optical devices, and magnetic resonance imaging (MRI) agents. This thesis reports the synthesis of novel metallic nitride EMFs based on Gd, Nd, Pr, Ce and La. These families of …

Hemeproteins Bathed In Ionic Liquids;Examining The Role Of Water And Protons In Redox Behavior And Catalytic Function, John Joseph Moran

ETD Archive

We investigate the changing behaviors of myoglobin and nitric oxide synthase (NOS) in the near-absence of bulk water and/or protons by using ionic liquid butyl methyl imidazolium tetrafluoroborate as a non-aqueous milieu. Through direct charge transfer and metalloprotein-mediated catalytic reduction of oxygen and nitric oxide, we shed light on diverging aspects on how the two hemeproteins face the scarcity of water and/or protons in bulk. Isotopic effect investigations using D2O further elucidates kinetic aspects of proton transfer. Finally, in the case of NOS oxygenase, pterin cofactor binding and NOS-mediated catalytic oxidation of L-arginine in ionic liquids interrogates proton and water …

A Lab To Stemulate Undergraduate Students Into Science, Technology, Engineering And Mathematics Majors, Nicole Lynn Speelman

Browse all Theses and Dissertations

The central focus is the development and implementation of a research/lab module for first year chemistry courses. Electrochemical techniques are utilized to study oxidation and reduction reactions of neurotransmitters with a poly(2,2'-Bithiophene) modified electrode. The goal is to excite students about chemistry and encourage them to continue studies in Science, Technology, Engineering, and Mathematics (STEM) during their undergraduate education. The lab module was created for Project REEL (Research Experiences to Enhance Learning) and will be illustrated with results typically obtained by students. The experiment is inquiry-based, which includes challenging questions students have to do collaboration and research to answer, as …

Synthesis And Electrochemical Studies In Microstructured Media, Jamie Norton

All Dissertations

In-situ electrochemical methods involving both oxidative and reductive mediators were employed to modify the oxidation state (doping level) of PEDOT polymers in colloidal PEDOT-coated silica core-shell particles that were prepared as a dispersion encapsulated in a hydrogel matrix. The modifications of the redox states of the PEDOT coating induced a change in the absorbance characteristics. A mediated electron transfer system was employed to ferry charge from the electrodes of the cell to the isolated particles. The mediator diffuses between the electrode surface and the PEDOT-coated particles to accomplish (de)doping. The developed system was a fully self-contained and electrically driven device. …

Electrochemical Remedy And Analysis For The Environment Based On The New Polymer-Dna Composite Material., Noor Feuza Hussain

Electronic Theses and Dissertations

In this work a new material, the conducting polymer-DNA composite, has been reported for the first time due to its promise in micro extraction, transfer, and release of cations under controlled potential conditions by using electrochemically assisted solid phase micro extraction (SPME). The Polypyrrole/DNA composite can be formed easily by oxidation of pyrrole monomers in the presence of chromosomal DNA by electropolymerization. Environmental significant pollutants such as Cd, Pb, Hg, Co, Zn, Cu, and Bi metal ions can be extracted from the aqueous solution and are able to be transferred to another medium defined as the release solution where the …

Synthesis, Characterization And Physical Studies Of Ligand Bridged Bimetallic Aqua Ruthenium (Ii) Polypyridyl Complexes, Matthew Thomas Mongelli

Seton Hall University Dissertations and Theses (ETDs)

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