Theses and Dissertations at Montana State University (MSU)
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Item Synthesis and characterization of boron-doped graphitic carbon for energy storage applications(Montana State University - Bozeman, College of Letters & Science, 2023) McGlamery, Devin Gray; Chairperson, Graduate Committee: Nicholas P. Stadie; This is a manuscript style paper that includes co-authored chapters.Carbonaceous materials offer great utility as a medium for electrochemical energy storage of ions or for the storage of chemical fuels. The low molecular weight of the second-row element carbon affords access to materials that express remarkably high gravimetric energy densities, and the robust nature of carbon-carbon bonds allow for good cyclability and longevity of carbon-based materials for use in energy storage applications. With the growing popularity and recent advancement of electric vehicles, current battery technologies are pushed to their limits in terms of capacities as well as in minimizing charging times. This has motivated great efforts to discover new lightweight materials that outperform what has traditionally been used in these applications. Alternative energy carriers, such as hydrogen, are also critical for the development of our energy landscape yet are plagued with their own technical challenges; mainly low volumetric energy densities and safety concerns associated with high pressure gas storage systems. Chapter 2 reviews hydrogen storage in today's society as well as provides a review of past synthetic methods to generate high boron content graphite (BC 3'); being a promising metastable material for the storage of alkali metal ions as well as for solid state hydrogen storage at near ambient conditions. Chapter 3 focuses on the discovery of a new lithium storage mechanism within a novel carbon-based material possessing a high hydrogen content that is tolerant of extremely fast charging, yet still expresses high reversible capacities. Chapter 4 presents a systematic investigation for the detection of chemical environments within BC 3' through an examination of unique spectroscopic properties that originate from the materials phonon structure. Chapter 5 explores the generation of boron and carbon binary phases by the co-pyrolysis of molecular precursors and establishes a density functional theory based approach to align the cracking temperatures of molecular feedstocks; affording access to bulk metastable materials that contain a homogeneous distribution of chemical environments. This work is concluded with an assessment of the materials investigated herein from the perspective of energy storage, as well as provides directions for future work.Item Catalysis with early and late transition metals: C-H activation at tantalocene hydrides and oxidative addition at palladium solvato complexes(Montana State University - Bozeman, College of Letters & Science, 2021) Rehbein, Steven Mark; Chairperson, Graduate Committee: Sharon Neufeldt; Matthew J. Kania and Sharon R. Neufeldt were co-authors of the article, 'Experimental and computational evaluation of tantalocene hydrides for C-H activation of arenes' in the journal 'Organometallics' which is contained within this dissertation.; Steven M. Rehbein and Sharon R. Neufeldt were co-authors of the article, 'Solvent coordination to palladium can invert the selectivity of oxidative addition' in the journal 'Organometallics' which is contained within this dissertation.Herein we present our work on transition metal catalysis using metals from two sides of the periodic table: C-H activation catalyzed by early transition metals and cross-couplings catalyzed by late transition metals. In the first part, a synergistic experimental and computational approach was employed to investigate the possibility of extending the reactivity of bent tantalocene hydrides beyond aromatic C-H activation to enable activation of aliphatic substrates. In situ monitoring of the characteristic 1 H NMR metal hydride signals in the reaction of Cp 2TaH 3 and related complexes with deuterated aromatic substrates allowed for the evaluation of reaction kinetics of catalyst decomposition, H/D exchange, and off-cycle reactions. The insight gained from in situ reaction monitoring with aromatic substrates, combined with computational analyses, allowed for the extension of this chemistry to intra- and intermolecular aliphatic C-H activation. This work represents the first example of aliphatic C-H activation by homogeneous tantalum hydrides. In the second part, we provide compelling evidence that solvent coordination to palladium during oxidative addition of chloroaryl triflates can result in an inversion of chemoselectivity of this step. Previous investigations attributed a solvent-dependent switch in chemoselectivity to the propensity of polar solvents to stabilize anionic transition states of the type [Pd(P t Bu 3)(X)]- (X = anionic ligand). However, our detailed investigations show that solvent polarity alone is not a sufficient predictor of selectivity. Instead, solvent coordinating ability is selectivity-determining, with polar coordinating and polar noncoordinating solvents giving differing selectivity, even in the absence of anionic ligands 'X'. A solvent-coordinated bisligated transition state of the type Pd(P t Bu 3)(solvent) is implicated by density functional theory calculations. This work provides a new mechanistic framework for selectivity control during oxidative addition.Item Hydrogen production from mechanically-activated basalt under experimental conditions simulating subglacial environments(Montana State University - Bozeman, College of Letters & Science, 2019) Mitchell, Kari Rebecca; Chairperson, Graduate Committee: Mark L. SkidmoreShearing of rocks containing silicate followed by reaction with water has previously been shown to produce hydrogen under experimental conditions relevant to subglacial environments. The abiotic production of hydrogen, carbon dioxide, methane, and other hydrocarbon gases has also been demonstrated in laboratory comminution experiments on rocks from glaciated catchments. Thus, the generation of these biologically useful gases (e.g. hydrogen and methane) beneath glaciers could serve as a source of reductant capable of sustaining microbial ecosystems beneath the ice. Despite the ubiquitous nature of basalt on both Earth and other planetary bodies, production of hydrogen and other gases from basalt through mechanical shearing and reaction with water has not been demonstrated. Basalts were collected from glaciated catchments in Iceland to test whether hydrogen and other gases were produced under laboratory conditions simulating glacial comminution. Rock samples were milled under an inert atmosphere, after which water was added and hydrogen and methane production measured over time. An average of 6.6 nmol hydrogen and 2.6 nmol methane per gram rock were produced after 168 hours from basalt samples tested; additionally, hydrogen peroxide and radicals were produced during grinding. The abiogenic production of hydrogen and methane under these simulated subglacial basaltic environments demonstrated in this study also has implications for supporting subglacial microbial communities during periods of extended glaciation, such as glacial-interglacial cycles in the Pleistocene and during the pervasive low-latitude glaciation of the Cryogenian. This mechanism of hydrogen production also has implications for the potential for life on icy worlds like Mars.Item Geomicrobiology of hydrogen in Yellowstone Hot Springs(Montana State University - Bozeman, College of Letters & Science, 2019) Lindsay, Melody Rose; Chairperson, Graduate Committee: Eric Boyd; Daniel R. Colman, Maximiliano J. Amenabar, Kirsten E. Fristad, Kristopher M. Fecteau, Randall V. Debes, John R. Spear, Everett L. Shock, Tori M. Hoehler and Eric S. Boyd were co-authors of the article, 'Geological source and biological fate of hydrogen in Yellowstone hot springs' which is contained within this dissertation.; Maximiliano J. Amenabar, Kristopher M. Fecteau, R. Vincent Debes II, Maria Clara Fernandes, Kirsten E. Fristad, Huifang Xu, Tori M. Hoehler, Everett L. Shock and Eric S. Boyd were co-authors of the article, 'Subsurface processes influence oxidant availability and chemoautotrophic hydrogen metabolism in Yellowstone hot springs' in the journal 'Geobiology' which is contained within this dissertation.Hydrogen (H 2) connects the geosphere and biosphere in rock-hosted ecosystems and has likely done so since early in Earth's history. High temperature hydrothermal environments, such as hot springs, can be enriched in H 2 and were likely widespread on early Earth. As such, linking the geological processes that supply H 2 to contemporary hot springs and the distribution of extant thermophilic organisms that can utilize H 2 as a component of their energy metabolism can provide insights into the environment types that supported early H 2 dependent life. Using a series of geochemical proxies, I developed a model to describe variable H 2 concentrations in Yellowstone National Park (YNP) hot springs. The model invokes interaction between water and crustal minerals that generates H 2 that can partition into the vapor phase during decompressional boiling of ascending hydrothermal waters. Fractures and faults in bedrock, combined with topographic features such as high elevation, allow for vapor to migrate and concentrate in certain areas of YNP leading to elevated concentrations of H 2. Metagenomes from chemosynthetic communities in YNP springs sourced with vapor-phase gas are enriched in genes coding for enzymes predicted to be involved in H 2-oxidation. A spring in an area of YNP (Smokejumper, SJ3) sourced with vapor-phase gas, that has the highest concentration of H 2 measured in YNP, and that is enriched in hydrogenase encoding genes was chosen to further examine the biological fate of H 2. SJ3 harbors a hyperdiverse community that is supported by mixing of oxidized meteoric fluids and volcanic gases. Transcripts coding for genes involved in H 2 uptake and CO 2 fixation were detected. The processes that control the availability of oxidants and their effect on the activity and abundance of H 2 dependent organisms was also investigated in two paired hot springs. H 2-oxidizing chemoautotrophs utilized different oxidants in the two springs and this underpinned differences in H2 oxidation activity and their identity. Together, these observations indicate that the subsurface geological processes of decompressional boiling and phase separation influence the distribution, identity, and activity of hydrogenotrophs through their combined effects on the availability of H 2 and oxidants.Item Analysis of water transport phenomena in thin porous media of a polymer electrolyte membrane fuel cell(Montana State University - Bozeman, College of Engineering, 2018) Battrell, Logan Robb; Chairperson, Graduate Committee: Ryan Anderson; Aubree Trunkle, Erica Eggleton, Lifeng Zhang and Ryan Anderson were co-authors of the article, 'Quantifying cathode water transport via anode humidity measurements in a polymer electrolyte membrane fuel cell' in the journal 'Energies' which is contained within this thesis.; Ning Zhu, Lifeng Zhang and Ryan Anderson were co-authors of the article, 'Transient, spatially resolved desaturation of gas diffusion layers measured via synchrotron visualization' in the journal 'International journal of hydrogen energy' which is contained within this thesis.; Virat Patel, Ning Zhu, Lifeng Zhang and Ryan Anderson were co-authors of the article, '4-D imaging of the desaturation of gas diffusion layers by synchrotron radiography' submitted to the journal 'Journal of power sources' which is contained within this thesis.This thesis explores and quantifies water transport related to the desaturation of the thin porous layer known as the Gas Diffusion Layer (GDL) associated with Polymer Electrolyte Membrane (PEM) fuel cells. The proper management of water within this layer is critical to optimal fuel cell performance. If there is not enough water, the membrane can become dehydrated, which leads to poor cell performance, but if too much water accumulates or becomes flooded, gas transport is restricted, which also lowers performance and can potentially lead to total cell failure. Understanding the desaturation of this layer is thus key to obtaining and maintaining optimal fuel cell performance. This behavior is explored both at the macroscale, through the quantification of the removal of excess water from an active fuel cell, as well as at the micro-scale, through the use of synchrotron X-ray computed tomography (X-ray CT) to visualize and quantify the desaturation of an initially flooded GDL. The macro-scale investigation extends the previously developed qualitative Anode Water Removal (AWR) test, which functions to identify when poor PEM fuel cell performance is due to excess water, to a diagnostic protocol that quantifies the amount of water being removed by the test through an analysis of the anode pressure drop. Results show that the protocol can be applied to a variety of fuel cell setups and can be used to quickly quantify water management capabilities of novel GDL materials. The microscale investigations show that while both convection and evaporation play a role in the desaturation, evaporation is required to fully desaturate the GDL. Additionally, the microscale investigation allows for the spatial segmentation of the GDL to identify local desaturation rates and temporal saturation profiles, which show that the overall desaturation of the GDL is a heterogeneous process that depends on initial conditions, flow field geometry and the natural anisotropy of the material. Results show that future control strategies and modeling studies will need to expand their investigated domains in order to accurately capture the fully heterogeneous nature of this process.Item Excited state processes in ruthenium(II) polypyridyl complexes and cerium oxide nanoparticles(Montana State University - Bozeman, College of Letters & Science, 2016) Stark, Charles William; Chairperson, Graduate Committee: Patrik R. Callis; Wolfgang J. Schreier, Janice Lucon, Ethan Edwards, Trevor Douglas and Bern Kohler were co-authors of the article, 'Interligand electron transfer in heteroleptic ruthenium(II) complexes occurs on multiple time scales' in the journal 'The journal of physical chemistry A ' which is contained within this thesis.Solar driven hydrogen production from water is a sustainable alternative to fossil fuels, but suffers greatly from the large energy cost associated with splitting water. This report uses ultrafast transient absorption and other spectroscopic techniques to analyze several components that show potential for this photocatalysis, in particular observing the excited state dynamics of electron separation and recombination. In ruthenium(II) polypyridyl systems, the rate of interligand electron transfer (ILET) was found to change with time, initially behaving as an ultrafast barrierless process, but transforming into a much slower activated process as excess energy is vibrationally released over 100 ps following excitation. The change in ILET rates lead to changes in the population of localized 3 MLCT states distributed among each ligand, which are initially randomized, but favor the lower energy bipyridine ligands at longer times. Three analogous ruthenium complexes were then linked via a triazole bridge to a cobalt(II) polypyridyl center known to catalyze the formation of H 2, observing the electron transfer from ruthenium to cobalt using emission decay signals of the ruthenium complex. The electron transfer decay pathway was slower and relatively minor compared to similar ruthenium(II)-cobalt(II) systems; however, this reduced efficiency can potentially be explained by localizations on peripheral ligands, as well as a possible energy barrier on the 5-position of phenanthroline. Finally, citrate coated CeO 2 nanoparticles displayed ultrafast trapping of holes upon excitation with UV light, forming significantly deeper traps than has been observed in other metal oxides. Transient absorption signals of the excited holes decayed over hundreds of picoseconds, with lifetimes dependent on the pH of the solution, indicating that the trapping sites are influenced by the surface of the nanoparticle. The corresponding electrons appear to form long lived Ce 3+ sites, observable on timescales of minutes. The fate of these Ce 3+ sites is also pH dependent, indicating that CeO 2 may be an effective water-splitting photocatalyst under basic conditions.Item Characterization of the [FeFe]-hydrogenase : toward understanding and implementing biohydrogen production(Montana State University - Bozeman, College of Letters & Science, 2014) Swanson, Kevin Daniel; Chairperson, Graduate Committee: John W. PetersHydrogen may provide an avenue for a clean renewable fuel source, yet the methods to produce hydrogen are either extremely energy intensive, rely on fossil fuels, or require expensive noble metal catalysts. Biology may hold the keys necessary to unlocking new technologies that could change how hydrogen is produced. Microbial processes also produce hydrogen and harbor enzymes that carryout the reversible reduction of protons to hydrogen gas. These enzymes are capable of producing hydrogen at high rates comparable to platinum catalysts, but biological hydrogen catalysts can produce hydrogen using abundant elements carbon, oxygen, nitrogen, sulfur, iron, nickel and selenium. Biological hydrogen catalysts are termed hydrogenases, and though hydrogenases use abundant elements they are extraordinarily complex. This has made it difficult to construct model complexes using inorganic synthesis that can replicate the activities of their biological counterparts. One way to circumvent this problem is to use microbial hydrogen production and let microbes produce and maintain these enzymes inside a cell. Microbial hydrogen production also has the added benefit that hydrogen production could be engineered to connect with other metabolic processes such as photosynthesis and fermentation. Engineering microbes for hydrogen production could eventually allow for the production of hydrogen using inexpensive energy inputs such as solar energy or waste materials. Yet, there are many barriers that need to be overcome in order to engineer a robust microbial organism. One of the primary difficulties of developing this technology has been the oxygen sensitivity of hydrogenases. Hydrogenases when exposed to atmospheric concentrations of oxygen either completely inactivate or their rates are significantly slowed. To engineer a hydrogenase that is more amenable for microbial hydrogen production, the optimization of expressing and purifying hydrogenase enzymes has been developed. Methodologies have been developed to characterize how oxygen inactivates hydrogenase enzymes, and a new methodology has been explored to help find novel hydrogenase gene sequences that may help in engineering oxygen tolerant enzymes.Item Hydrogen absorption kinetics at titanium surfaces as measured using ERDA(Montana State University - Bozeman, College of Letters & Science, 1996) Teter, Marcus AltonItem Radiative mean lifetime measurement in N=2 hydrogen(Montana State University - Bozeman, College of Letters & Science, 1977) Kelley, Edward FrankItem Non-adiabatic spin transitions in metastable hydrogen(Montana State University - Bozeman, College of Letters & Science, 1975) Hight, Ralph Dale