Trauma remains the leading cause of mortality between the ages of 1 and 44 in the United States. Uncontrolled blood loss accounts for 50 % of all battlefield deaths and up to 25 % of civilian trauma deaths. This mortality is often the result of a severe clotting impairment known as acute traumatic coagulopathy. Therefore, hemorrhage control remains the a priori goal in the care of the critically injured patient. While great advances have been made in the resuscitation of the injured patient, attenuating bleeding and correction of coagulopathy remain vexing clinical problems. Current clotting treatments are plagued by concerns over excessive cost, poor stability, and safety issues.

In this defense, I present a silica nanoparticle (SNP) functionalized with polyphosphate (polyP) that mediates the body’s natural clotting process. SNPs initiate the blood clotting system’s contact pathway, while the endogenous short-chain polyP accelerates the common pathway via rapid formation of thrombin. This enhances the overall blood-clotting system, both by accelerating fibrin generation and by facilitating the regulatory anticoagulation mechanisms essential for hemostasis. Because of its low production cost, long-term stability at ambient conditions, and the potential to minimize side effects seen in current treatments, the polyP-SNP therapeutic has the possibility to enable the body to re-establish hemostasis after traumatic injury, preventing massive blood loss and saving lives.

In the pursuit of energy efficiency, there is a demand for systems capable of

recovering waste heat. A temperature gradient across a thermoelectric material

results in the thermal diffusion of charge carriers from the hot side to the cold

side, giving rise to a voltage that can be used to convert waste heat to electricity.

Silicon germanium (SiGe) alloys are the standard materials used for thermoelectric

generators at high temperatures.

We report an alternative method for preparing p-type Si1-xGex alloys from

a boron-doped silica-germania nanocomposite. This is the first demonstration of

the thermoelectric properties of SiGe-based thermoelectrics prepared at temperatures

below the alloy's melting point through a magnesiothermic reduction of the

(SiO2)1-x(GeO2)x. We observe a thermoelectric power factor that is competitive

with the literature record for the conventionally prepared SiGe. The large grain

size in our hot pressed SiGe limits the thermoelectric figure of merit to 0.5 at

800C for an optimally doped p-type Si80Ge20 alloy.

A phosphorus-doped oxide can yield n-type Si1-xGex; however, the current

processing method introduces a background boron content that compensates ~10%

of the donor impurities and limits the thermoelectric power factor.

Spark plasma sintering of the nano-Si1-xGex yields a heterogeneous alloy with

thermal conductivity lower than that of the hot pressed homogeneous alloy due

to a reduction in the average crystallite size. Magnesiothermic reduction in the

presence of molten salts allows some control over crystallite growth and the extent

of Si-Ge alloying.

Platinum group metals (PGMs) are well established and widely used for catalytic processes. It has been demonstrated that PGMs can be superior catalysts for hydrocarbon conversion reactions compared to the industry standard. However, the findings in academic labs cannot always translate directly to industrial usage. One limitation to using PGMs for large scale processes is sometimes cost. Access to an inexpensive and highly efficient catalyst could be a step towards using recovered hydrocarbons, in the form of natural gas and shale gas, more widely for energy production.

While platinum group metal species have been intensively examined,

less is know about reactivity associated with ionic PGMs in oxides.

Using ionic species could be a route to achieving more efficient conversion of mixed hydrocarbon feedstocks to fuels and commodity chemicals.The work presented in this dissertation focuses on Pd-substitution in binary and complex oxides along with model compounds containing noble metals, with the aim of preparing an inexpensive and

robust C-H bond activation catalyst. With an emphasis on preparation methods and careful characterization, it has been a goal of this work to establish structure-property relationships in oxide catalysts.

Initial work on Pd--substitution in CeO₂ has lead to the development of ultrasonic spray pyrolysis (USP) as a method for preparing substituted oxides having relatively high surface area. Phase pure Pd--substituted perovskites were also prepared using this technique. Methane partial oxidation reactions on Pd-substituted CeO₂ provided some understanding of Pd substitution in oxides. It was determined that ionic Pd when substituted in CeO₂ is readily reduced to fcc-Pd. Investigation of more complex oxides that could stabilize ionic Pd under reducing conditions through inductive effects became the target of subsequent research.

Pd-substituted LnFeO₃ (Ln = Y, La) showed promising results for increased stabilization of Pd ions under methane partial oxidation conditions. Microwave-assisted heating methods were employed to to prepare these materials very rapidly. With just several minutes of microwave-assisted heating, Pd-substituted perovskite materials were prepared for characterization and testing.

With the help of our collaborators, Pd--substituted LaFeO₃ was applied as a catalyst precursor material for aryl chloride coupling under mild conditions.

The focus was shifted to model compounds, noble metal complex oxides, La₂BaPdO₅ and La₂BaPtO₅, already having unique noble metal sites. The thermal stability of these complex oxides compared to binary oxides was both an attractive property for probing ionic PGM catalysis and a fascinating feature, worthy of further investigation.

Using density functional theory, the electronic structures of La₂BaPdO₅ and La₂BaPtO₅ were compared

to those of the binary PdO and PtO oxides. It was determined that a shift in the O 2p band is responsible for the increased stability in complex oxides.

Through this study of Pd ions, we have developed two novel methods for preparation of substituted and stiochiometric oxide materials. A combination of characterization methods, including X-ray diffraction and X-ray photoelectron spectroscopy, are required to understand the structure of these complicated materials. Often times, more advanced characterization, such as neutron diffraction and extended X-ray absorption fine structure measurements, provide the necessary insights to understanding the structures and properties of oxide catalysts. In this dissertation, preparation and characterization are emphasized for ionic PGM and oxide catalysts.

When illuminated with visible light, nanostructured noble metals exhibit a strong

plasmon resonance at wavelength, p, that has been shown to be sensitive to its size,

structure, the dielectric properties of the surrounding medium, and charge density. The

tunability of the plasmon resonance has allowed metal nanosystems to be fabricated with

resonances matching the solar spectrum for us in plasmon promoted catalysis, plasmonic

photovoltaics, and surface-enhanced raman spectroscopy. Here we use UV-Visible spectroscopy

to track the shifts of the plasmon resonances from an array of gold nanoparticles

buried under metal oxide layers of varying thickness when in contact with one of two bulk

metals: aluminum or silver. By assuming the array of gold nanoparticles and metal-oxide

layers to be an optically homogenous lm of core-shell particles on a substrate, we developed

a Maxwell-Garnett effective medium approximation to extract reliable optical

parameters for the gold nanoparticles, yielding their charge state before and after contact

with the bulk metal.

Based on the optical parameters extracted from our model, we nd the magnitude of

charge transfer from the bulk metal to the gold nanoparticle is independent of the work

function of the bulk metal. Furthermore, when gold is used as the bulk layer in contact

with the gold nanoparticles, we measured an appreciable amount of charge transfer to the

gold nanoparticles, failing to support the well-established model for electrostatic contact

electrication. Instead, we attribute the charge transfer to the so called plasmoelectric

effect, an optically induced charge transfer mechanism, in which the gold nanoparticle

modifes its charge density to allow its resonant wavelength to match that of the incident

light. We show, however, that in our devices the Schottky barriers between the metals

and the metal oxide layers create a rectication effect that favors electron transfer from

the bulk metal to the nanoparticles over the reverse effect.

The ability to synthesize a wide range of nanostructured materials, as well as integrate them into larger systems, is fundamental to the development of next-generation micro- and optoelectronic devices, sensors, and energy harvesting and storage technologies. Toward this goal, we have developed a versatile, plasma spray-like deposition technique, based on flow-through microhollow cathode discharges (MHCDs) at 10-100 Torr. These microplasma jet sources can deposit nanoparticles, dense layers, and structured thin films of crystalline materials on virtually any surface (e.g., conductors, insulators, polymers, fibers, and lithographic patterns). Supersonic microplasma jets are seeded with organometallic precursors under oxidizing conditions to create a directed flux of growth species (e.g., atoms, ions, clusters, and/or nanoparticles) that are subsequently ‘spray-deposited’ onto the surface of interest at room temperature. A diverse range of nanostructured transition metal oxide materials, e.g., CuO, MnO2, RuO2, NiO, Fe2O3, CoxOy, and spinels (NiCo2O4) can be realized with the technique. These films were then used for electrochemical energy storage applications and are discussed with emphasis on the fabrication of microscale energy storage devices. We also highlight detailed measurements of Trot, Tvib, Te, and ne on various jets made using trace gas optical emission spectroscopy (OES) and Langmuir probe studies.

A great deal of scientific research in recent decades has been focused on bringing new

and more efficient forms of solar energy to market, as well as making existing solar energy

technology more viable. Two of the central issues in this research have been energy stor-

age, to account for the discrepancy between hours peak production and hours of usage,

and the efficiency of photovoltaic devices. Coming from an infrastructure built off of

burning chemical fuels, storing solar energy in chemical bonds to make so-called ’solar

fuels’ has been one of the major area of research. This involves both photovoltaic and

electrocatalytic aspects, which can be incorporated into single devices or implemented

separately with a discrete photovoltaic driving an electrochemical reaction. We have

used in-operando Raman spectroscopy to to improve understanding of a popular anode

material for the splitting of water, Manganese Oxide, as it undergoes structural changes

during operation; with implications for the production of more efficient anodes.

Further, we have the sought to improve the functionality of existing materials by

the use of oscillations of electrons in metal nanostructures. The collective oscillations of

conduction electrons at the surface of metals, called surface plasmons, induce an electric

field in surrounding dielectric materials called the surface plasmon polariton. This can be

tuned by manipulation of the structure of the metal on the length scale of the mean free

path of electrons in the metal. By careful manipulation of noble metal nanostructures, we have been able to manipulate the properties of semiconductor electrodes - shifting

the product distribution of CO2 reduction on Cu2 O. Additionally, we have been able

to use plasmonic nanoparticles to make pan-chromatic light aborbers for photovoltaic

applications.