Physical Sciences and Mathematics Commons^™

Structural, Magnetic, Electrical, Pseudocapacitive, And Electrocatalytic Properties Of Bilayered Ruddlesden-Popper Oxides., Chandana Kananke-Gamage

Electronic Theses and Dissertations

Ruddlesden Popper (RP) oxides are perovskite-derived functional materials with the general formula An-1Aʹ2BnO3n+1, where A/Aʹ is often a lanthanide or alkaline earth metal, and B is usually a transition metal. These materials contain perovskite-like connectivity, where BO6 units share apexes to form layers that are stacked above each other. The number of layers in each stack is represented by n in the above formula. The spaces between stacks are often occupied by lanthanide or alkaline-earth metals (Aʹ-site metals), which also reside in intra-stack spaces (A-site) between the octahedra. Oxide materials derived from perovskites have been studied for a wide range …

Geothermal Energy And Its Impacts On The Environment, Aditi Gorthy, Nathan Tran, Laureen Pierre-Louis

Mako: NSU Undergraduate Student Journal

From the multitude of energy sources that we have developed throughout the eons, renewable energy or “clean energy” has been on the rise to combat global warming and climate change which burning nonrenewable sources of energy have contributed to. Before geothermal energy is used as part of the mainstream energy sources some aspects must be analyzed and resolved. Unfortunately, geothermal power plants still release pollutants, such as carbon dioxide and sulfur dioxide, into the environment and cause general environmental disruptions due to drilling and changes in land formations. Recent and future studies have been and should be conducted to find …

Saturable Absorption Of Free-Electron Laser Radiation By Graphite Near The Carbon K-Edge, Lars Hoffmann, Sasawat Jamnuch, Craig P. Schwartz, Tobias Helk, Sumana L. Raj, Hikaru Mizuno, Riccardo Mincigrucci, Laura Foglia, Emiliano Principi, Shervin Fatehi

Chemistry Faculty Publications and Presentations

The interaction of intense light with matter gives rise to competing nonlinear responses that can dynamically change material properties. Prominent examples are saturable absorption (SA) and two-photon absorption (TPA), which dynamically increase and decrease the transmission of a sample depending on pulse intensity, respectively. The availability of intense soft X-ray pulses from free-electron lasers (FELs) has led to observations of SA and TPA in separate experiments, leaving open questions about the possible interplay between and relative strength of the two phenomena. Here, we systematically study both phenomena in one experiment by exposing graphite films to soft X-ray FEL pulses of …

Investigation On The Synthesis, Application And Structural Features Of Heteroaryl 1,2-Diketones, Robert J. Wehrle, Alexander Rosen, Thu Vu Nguyen, Kalyn Koons, Eric Jump, Mason Bullard, Natalie Wehrle, Adam Stockfish, Patrick M. Hare, Abdurrahman Atesin, Tülay A. Ateşin, Lili Ma

Chemistry Faculty Publications and Presentations

A set of unsymmetrical heteroaryl 1,2-diketones were synthesized by a heteroarylation/oxidation sequence with up to 65% isolated yields. Palladium catalyst XPhos Pd G4 and SeO2 were the key reagents used in this methodology, and microwave irradiation was utilized to facilitate an efficient and ecofriendly process. The application of heteroaryl 1,2-diketones is demonstrated through the synthesis of an unsymmetrical 2-phenyl-3-(pyridin-3-yl)quinoxaline (5a) from 1-phenyl-2-(pyridin-3-yl)ethane-1,2-dione (4a). The lowest energy conformations of 4a and 5a were located using Density Functional Theory (DFT) at the M06-2X/def2-TZVP level of theory. Two lowest energy conformations of 4a differ with respect to the position of the N atom …

Transistion Metal Chalcogenides And Phosphides For Energy Storage And Conversion Through Water Splitting, Kelsey Thompson

Electronic Theses & Dissertations

In contemporary society, there are many different ways that energy is used in daily life. From applications that require a high energy density to long-term storage in a stable manner, the requirements for energy usage are diverse. Therefore, the greater the number of uses a designed material exhibits, the more practical it may be for wide-scale manufacture. Two areas of particular interest for energy applications are fuel cells (to generate energy) and supercapacitors (to store energy). To provide cheaper and more durable alternatives for energy storage, electrodes containing CoMoO₄, NiMoO₄, CoMoS₄, NiMoS₄, …

Band-Gap Tuning In Acceptor-Donor-Acceptor Boron Difluoride Formazanates, Francis L. Buguis, Michael Anghel, Joe B. Gilroy, Jasveer S. Dhindsa

Chemistry Publications

π-Conjugated molecules with acceptor-donor-acceptor (A-D-A) electronic structures are an important class of materials due to their tunable optoelectronic properties and applications in, for example, organic light-emitting diodes, nonlinear optical devices, and organic solar cells. The frontier molecular orbital energies, and thus band gaps, of these materials can be tuned by varying the donor and acceptor traits and π-electron counts of the structural components. Herein, we report the synthesis and characterization of a series of A-D-A compounds consisting of BF₂ formazanates as electron acceptors bridged by a variety of π-conjugated donors. The results, which are supported by DFT calculations, demonstrate …

Advancements Toward Sustainable Solar Fuel Production Utilizing Reductive Homogeneous Electro- And Photocatalysis, Hunter Pratt Shirley

Electronic Theses and Dissertations

Molecular CO2 and H+ reductive catalysts, whether they be electro- or photocatalytic, have been shown to be possible routes of harnessing solar energy in a clean, renewable manner. There are few electrocatalysts operating at reasonable overpotentials to prove useful in artificial photosynthetic systems, and there are a number of environmental factors within these systems that have yet to be evaluated. Photo-driven catalysis is rare, difficult to control, and rarely provides high-value CO2 reduction products. I report herein an exceptionally low overpotential H+ reduction catalyst, a method of modulating electrocatalysts in-situ to improve performance, a first-of-its-kind mononuclear proton reduction photocatalyst, a …

Investigating Transfer Of Energy Concepts Learned In Physics To Biology Contexts, Brittany Mureno, Eric Mckenzie

Scholars Week

Problem solving interviews were used to investigate student understanding of energy concepts in a biology course for preservice K-8 teachers. Interview subjects constructed an energy-based explanation for a biology scenario. Subjects had previously taken a physics course in which an energy-based model for interactions had been developed. Interviews were transcribed and analyzed to identify common themes in student reasoning. These themes describe discipline-specific understanding, but also cut across disciplines, providing insight into how learners make sense of energy as a unifying concept.

Hierarchical Plasmon Resonances In Fractal Structures, Isobel C. Bicket, Edson P. Bellido, Danielle M. Mcrae, Francois Lagugne-Labarthet, Gianluigi A. Botton

Chemistry Publications

An equilateral triangular prism is used as the fundamental building block to con- struct additive Sierpinski fractals, enabling new surface plasmon resonances (SPR) in the first three generations of Sierpinski triangles, as well as topological intermediaries between generations. The modes are characterized using electron energy loss spectroscopy accompanied by eigenmode calculations and optical finite-difference time domain simulations. The complex fractal geometries present a predictable hierarchy of new resonances, each arising from the previous generational building blocks used to construct the fractal. Intermediate structures break the polarization degeneracy of the equilateral fractals while maintaining a rich multiband spectral response. Engineering defects …

Tools For Prescreening The Most Active Sites On Ir And Rh Clusters Toward C−H Bond Cleavage Of Ethane: Nbo Charges And Wiberg Bond Indexes, Yingbin Ge, Anna Le, Gregory J. Marquino, Phuc Q. Nguyen, Kollin Trujillo, Morgan Schimelfenig, Ashley Noble

All Faculty Scholarship for the College of the Sciences

B3LYP calculations were carried out to study the insertion of iridium (Ir) and rhodium (Rh) clusters into a C−H bond of ethane, which is often the ratelimiting step of the catalytic cycle of oxidative dehydrogenation of ethane. Our previous research on Ir catalysis correlates the diffusivity of the lowest unoccupied molecular orbital of the Ir clusters and the relative activities of the various catalytic sites. The drawback of this research is that the molecular orbital visualization is qualitative rather than quantitative. Therefore, in this study on C−H bond activation by the Ir and Rh clusters, we conducted analyses of natural …

Carving Plasmon Modes In Silver Sierpiński Fractals, Isobel C. Bicket, Edson P. Bellido, Danielle M. Mcrae, Francois Lagugne-Labarthet, Gianluigi A. Botton

Chemistry Publications

The surface plasmon resonance (SPR) modes of the first three generations of a Sierpiński fractal triangle are investigated using electron energy loss spectroscopy (EELS) complemented with finite difference time domain simulations. The Sierpiński fractal geometry is created in a subtractive manner, by carving triangular apertures into the triangular prism of the previous fractal generation. The ability of the fractal antenna to efficiently utilize space in coupling to long wavelength excitations is confirmed on the single nanostructure level via redshifting of the primary dipole mode as the fractal generation is increased. Through application of the Babinet principle, it is demonstrated that …

Our Energy Future, Fall/Winter 2007, Issue 15

Sustain Magazine

No abstract provided.

Unconventional Energy, Fall/Winter 2015, Issue 31

Sustain Magazine

No abstract provided.

Effects Of Disorder On Thermoelectric Properties Of Semiconducting Polymers, Zlatan Aksamija, Dhandapani Venkataraman, Connor J. Boyle, Meenakshi Upadhyaya

Zlatan Aksamija

Metal-Organic Frameworks: Photophysics, Energy Transfer, And Electronic Structure, Ekaterina A. Dolgopolova

Theses and Dissertations

The current landscape of technological and industrial related fields is looking for novel materials with enhanced performances, which will not only improve various fields in science, but also can ensure increased environmental safety. Recently, metal-organic frameworks (MOFs) have been shown as a promising type of material for a wide range of applications including gas storage and separation, sensing, and heterogeneous catalysis. The main advantages of MOFs rely on their modular structures as well as their porosity. For instance, the modular nature of MOFs provides a control over chromophore arrangement, systematic tuning of ligand design and synthetic conditions allowing one to …

Heat And Work, The First Law Of Thermodynamics From The Boltzmann Pov, Carl W. David

Chemistry Education Materials

The First Law of Thermodynamics is discussed in terms of the Boltzmann distribution.

Nano To Global: Small Structures And Their Impact On Energy Markets, Kurt W. Kolasinski

Sustainability Research & Practice Seminar Presentations

No abstract provided.

Electronic Effect Of Platinum Alloy Catalysts On Olefin Hydrogenation Kinetics, Colin Reedy, Jeff Miller, Stephen Purdy

The Summer Undergraduate Research Fellowship (SURF) Symposium

Dehydrogenation of alkanes is the first step in transforming light hydrocarbons into liquid fuels and chemicals. This process has traditionally used platinum alloys as catalysts. Alloys are used industrially because they have a greater selectivity than monometallic platinum. Alloying platinum with an inactive promoter modifies the crystalline structure of the surface (geometric effect), and the 5d electrons in platinum responsible for chemistry (electronic effect); both have been suggested to be primarily responsible for dehydrogenation selectivity in platinum alloys. Alloy catalysts have been synthesized using early 3d transition metal promoters with the same Pt₃M crystal structure. X-Ray Absorption Spectroscopy …

Nanocomposites Of Polypyrrole And Cobalt Oxide As Efficient And Stable Multifunctional Materials For Supercapacitors And Overall Water Splitting, Ahlam Alghamdi

Electronic Theses & Dissertations

NANOCOMPOSITES OF POLYPYRROLE AND COBALT OXIDE AS EFFICIENT AND STABLE MULTIFUNCTIONAL MATERIALS FOR SUPERCAPACITORS AND OVERALL WATER SPLITTING

An Abstract of the Thesis by

Ahlam Alghamdi

The main objective of this study is to synthesize nanostructured cobalt oxide decorated on polypyrrole using a facile method for energy applications. For this, polypyrrole was first synthesized using a chemical polymerization method. In the second step, a varying amount of cobalt oxide was decorated on polypyrrole using a hydrothermal process. The synthesized materials were structurally and electrochemically characterized. It was observed that the electrochemical properties of the composites depend on their composition. The …

Lithium And The Foreseeable Future, Paolo Vargas

Mechanical Engineering Undergraduate Honors Theses

This paper aims to clarify the uncertainties regarding worldwide lithium resource availability in the years to come. Previous studies made on the subject are presented with some ambiguity and this work intends to fill the gaps. The information and data presented throughout this script with respect to global lithium resources and reserves are mostly based on data released by the United States Geological Survey (USGS). Lithium resource availability in the future is a point of paramount significance primarily for the automotive, portable electronics, and the power generation industry. Since, a change of supply would ultimately affect the price of lithium, …

Functionalized Nanoporous Carbon Scaffolds For Hydrogen Storage Applications, Christopher Carr

Dissertations

Recent efforts have demonstrated confinement in porous scaffolds at the nanoscale can alter the hydrogen sorption properties of metal hydrides, though not to an extent feasible for use in onboard hydrogen storage applications, proposing the need for a method allowing further modifications. The work presented here explores how the functionalization of nanoporous carbon scaffold surfaces with heteroatoms can modify the hydrogen sorption properties of confined metal hydrides in relation to non-functionalized scaffolds (FS). Investigations of nanoconfined LiBH₄and NaAlH₄indicate functionalizing the carbon scaffold surface with nitrogen can shift the activation energy of hydrogen desorption in excess of …

Preventing Crossover In Redox Flow Batteries Through Active Material Oligomerization, Susan A. Odom

Chemistry Faculty Publications

No abstract provided.

Sodium Borohydride For The Near-Future Energy: A ''Rough Diamond'' For Turkey, Ümi̇t Bi̇lge Demi̇rci̇

Turkish Journal of Chemistry

Boron-based materials are potential solutions in the field of energy. They have been regarded as hydrogen storage materials, liquid fuels of direct liquid-fed fuel cells (DLFCs), electrolytes of battery, and/or energetic substances. A typical example is sodium borohydride (NaBH$_{4}$. In sodium hydroxide-stabilized aqueous solutions, it is seen as an efficient H$_{2}$ generator or a performing fuel of DLFCs. Actually, it plays a wider role; it is also the precursor of several boron-based materials of interest in the field of energy. In other words, it is indirectly considered for other energy applications, i.e. solid electrolytes of all solid-state batteries and hypergolic …

Raman Spectroscopy Of Oxygen Evolution Catalysts And Psii Manganese Model Compounds, Sergei Shmakov, Daniel A. Hartzler, Alireza Karbakhsh Ravari, Yulia Pushkar

The Summer Undergraduate Research Fellowship (SURF) Symposium

Photosynthesis is the basis of life on earth, and oxygen evolution catalysts are key components of this complicated, yet not fully understood process. Photosystem II, a large membrane bound pigment-protein complex, is the key system that facilitates oxygenic photosynthesis via the oxygen evolving complex (a natural oxygen evolving catalyst). It is a key component in oxygen producing catalysts, which can be used in fields such as energy production and biomimetic catalysts. The oxygen evolution cycle, or Kok cycle going within it is still not studied completely. In this project, we were studying the vibrational (and structural) state of a Manganese …

Homogeneous Ligand-Centered Hydrogen Evolution And Hydrogen Oxidation : Exploiting Redox Non-Innocence To Drive Catalysis., Andrew Z. Haddad

Electronic Theses and Dissertations

Hydrogen is a promising carbon-free fuel / energy carrier and is an essential building block for many industrial and agricultural processes. Rising energy demands have ignited interest in the development of carbon-free and carbon neutral energy sources. In this context, hydrogen is an attractive candidate—being energy-dense, carbon-free—and easily accessible through a two-electron reduction of water. Accordingly, many electrochemical homogeneous catalyst systems have been studied, with a focus on understanding the mechanism of hydrogen evolution proceeding through metal-hydride intermediates. However, there has been a renaissance in hydrogen evolution reaction (HER) catalyst design, with many groups implicating ligand redox non-innocence as a …

Size And Site Dependence Of The Catalytic Activity Of Iridium Clusters Towards Ethane Dehydrogenation, Yingbin Ge, Hao Jiang, Russell Kato, Prasuna Gummagatta

All Faculty Scholarship for the College of the Sciences

This research focuses on optimizing transition metal nanocatalyst immobilization and activity to enhance ethane dehydrogenation. Ethane dehydrogenation, catalyzed by thermally stable Ir_n (n = 8, 12, 18) atomic clusters that exhibit a cuboid structure, was studied using the B3LYP method with triple-ζ basis sets. Relativistic effects and dispersion corrections were included in the calculations. In the dehydrogenation reaction Ir_n + C₂H₆ → H−Ir_n−C₂H₅ → (H)₂−Ir_n−C₂H₄, the first H-elimination is the rate-limiting step, primarily because the reaction releases sufficient heat to facilitate …

Characterization Of S-Swcnt/Pf-Pd Dispersions And Networks, Tamara N. El-Hayek Ms., Jeffrey Blackburn, Andrew Ferguson, Tammy Pheuphong

STAR Program Research Presentations

Single-Walled Carbon Nanotubes (SWCNTs) are being investigated for their use in a wide variety of renewable energy applications. Their unique physical properties contribute to desirable traits such as a high carrier mobility, strong optical absorption and tunable electronic band gap. Unfortunately, due to variability in certain parameters, SWCNTs are limited in their application. The major drawback is that SWCNTs are variable in size and type and typical synthetic methods are not selective. As a result, selective methods must be developed in order to sort these tubes and extract those which are desirable for a particular application. Though there are several …

Development Of A Novel Polymer-Garnet Solid State Composite Electrolyte Incorporating Li-La-Zr-Bi-O And Polyethylene Oxide, Muhammed Ramazan Oduncu

Open Access Theses

Current lithium ion batteries are comprised of organic liquid electrolytes - a mixture of lithium salts and binary solvents such as ethylene carbonate (EC) and dimethyl carbonate (DMC). The main drawbacks of this liquid mixture related to safety are flammability of the organic solvents and chemical instability with the electrode materials. To date, various ceramic and polymer materials have been considered which overcome safety issues. However, a common problem of these solid state materials is that they are not able to provide high ionic conductivity at ambient temperatures. Garnet-type cubic Li7La 3Zr2O12 ceramic material has attracted much interest because of …

Multiple-Time Step Ab Initio Molecular Dynamics Based On Two-Electron Integral Screening, Shervin Fatehi, Ryan P. Steele

Chemistry Faculty Publications and Presentations

A multiple-timestep ab initio molecular dynamics scheme based on varying the two-electron integral screening method used in Hartree–Fock or density functional theory calculations is presented. Although screening is motivated by numerical considerations, it is also related to separations in the length- and timescales characterizing forces in a molecular system: Loose thresholds are sufficient to describe fast motions over short distances, while tight thresholds may be employed for larger length scales and longer times, leading to a practical acceleration of ab initio molecular dynamics simulations. Standard screening approaches can lead, however, to significant discontinuities in (and inconsistencies between) the energy and …

Observation Of Ground-State Two-Neutron Decay, M Thoennessen, Z Kholey, A Spyrou, E Lunderberg, Paul A. Deyoung, H Attanayake, T Baumann, D Bazin, B A. Brown, G Christian, D Divaratne, S M. Grimes, A Haagsma, J E. Finck, N Frank, B Luther, S Mosby, T Nagi, Graham F. Peaslee, W A. Peters, A Schiller, J K. Smith, J Snyder, M Strongman, A Volya

Faculty Publications

Neutron decay spectroscopy has become a successful tool to explore nuclear properties of nuclei with the largest neutron-to-proton ratios. Resonances in nuclei located beyond the neutron dripline are accessible by kinematic reconstruction of the decay products. The development of two-neutron detection capabilities of the Modular Neutron Array (MoNA) at NSCL has opened up the possibility to search for unbound nuclei which decay by the emission of two neutrons. Specifically, this exotic decay mode was observed in¹⁶Be and ²⁶O.