Transition metal oxynitrides are of growing interest for their use as electrocatalyst for nitrogen reduction reaction. The metals in the oxynitride used for catalytic process are stabilized in intermediate state for effective activation of nitrogen. Therefore, studying the interaction of metal oxynitrides films to ambient exposure is necessary. Here, sputter deposited vanadium oxynitride is compared to cobalt oxynitride using insitu Auger electron spectroscopy (AES), ex situ X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). After deposition in Ar/N2 environment, in situ AES spectra indicate that film is vanadium oxynitride despite oxygen is not the reactive gas. In contrast, in situ AES indicate film is pure cobalt nitride at the same base pressure and deposition condition (as vanadium). For ambient exposure, in situ AES indicate the incorporation of oxygen in the cobalt nitride film to form cobalt oxynitride. Ex situ XPS indicate both films get more oxidized but uniformly distributed as there is only slight difference in grazing and normal emission XPS. XRD and SEM also indicate how homogeneously distributed both films are. These finding confirms how important it is that transition metal centers are kept in intermediate oxidation state for the activation of nitrogen bond.

Deposition of solid state materials span a wide variety of methods and often utilize high energy sources such as plasmas and ultra-violet light resulting in a wide variety of characteristics and applications. A fundamental understanding is essential for furthering the applications of these materials which include catalysis, molecular filtration, electronics, sensing devices, and energy storage among others. A combination of experimental and theoretical work is presented here on several materials including 2D silicates on Pd, boron oxide, and vanadium oxynitride. Silicate formation under low energy electron microscopy demonstrate film permeability to oxygen, while ab initio molecular dynamics simulations reveal the possible initial mechanisms associated with the formation of boron oxide films during atomic layer deposition. Lastly, vanadium oxynitrides have shown preferential sputtering of N over O sites and theoretical binding energies serve as a guide for assigning experimental x-ray photoelectron spectra.

Nanofluidic is an emerging field of applying fluid properties in nanochannels or nanostructures. The nanoporous channel with a pore size of less than 100 nm will strongly affect the motion of the fluid. Meanwhile, the pore environment, such as hydrophilic and hydrophobic properties, charge density, and host-guest recognition would be crucial for the transportation of molecules and ions in the pore. This thesis is focused on the synthesis, characterization of nanofluidic membranes and their applications to reverse electrodialysis. Chapter 1 focuses on the importance and objective of this work. Chapter 2 gives an overview of nanofluidic and classical nanofluidic structure–covalent organic frameworks (COFs). In Chapter 3, a series of COFs membranes with different surface charge densities were designed by employing a multivariate (MTV) strategy. A volcano-like relationship between the surface charge density and output power density was observed when the membranes were applied for osmotic energy harvesting. Chapter 4 integrates the temperature gradient to the covalent organic frameworks nanofluidic system to further explain the thermophoretic mobility of ions. The recorded osmotic energy production density was obtained while ion concentration polarization was alleviated with increasing hydrodynamic convection effects. In Chapter 5, a coupled photon-electron-ion transport behavior across ionic covalent organic framework …

In this thesis, micro-mechanical properties and corrosion resistance of laser powder bed fusion (L-PBF) processed additive manufactured (AM) 316L stainless steel parts were investigated for different combinations of processing parameters. Various laser powers were employed for the fabrication of all AM 316L stainless steel parts. Nanoindentation, areal roughness, and electron backscattered diffraction (EBSD) characterization were used to characterize the surface of the AM samples prior to corrosion testing. Open circuit potential (OCP), linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization tests were done to compare AM L-PBF 316L stainless steels with different processing parameters. Overall, it was observed that the AM part having a 56.67 J/mm3 volumetric energy density (VED) exhibits the best micro-mechanical characteristics. This sample also had the lowest areal surface roughness and smallest grain size. Consequently, this parameter combination had better corrosion resistance compared to the other AM processed 316L parts. The results are useful in process calibration when fabricating for corrosion resistance applications and provide insights into the relationship among nano-mechanical, crystallography, and long-term corrosion performance.

The rise of nutraceutical health formulations has increased the need for more stringent analytical testing methods. Complex matrices present a new problem when determining concentration of compounds of interest. The presented method uses LC-MS analysis with a novel sample preparation method in the determination of Beta-hydroxybutyric acid in health formulations. The use of an aqueous analytical column allows for separations of polar compounds after non-polar compounds are removed through C18 packed column filtration. The samples were analyzed through time-of-flight mass spectrometry and results show that this is an effective method for the presented samples with a range of expected concentrations of total BHB was from 11.80% to 38.92%. It was seen that all samples exhibited a less than 10% percent deviation from the expected concentrations of the nutraceutical health samples with the highest being 9.74 % for sample 9 and the lowest being sample 3 with a deviation of 0.08 % from expected values.

Mechanical pressure offers unique control over the energy landscape of chemical reactions, opening up pathways that are inaccessible through conventional thermochemistry. We hypothesize that the reduced dimensionality defines the conformational space of the high-pressure reaction, giving rise to new selectivity that is unavailable in 3D systems. Here, we demonstrate this concept through the pressure-controlled topochemical polymerization of the diacetylene molecule deca‐3,5‐diyn‐1‐amine (DDA) incorporated in the two-dimensional (2D) perovskite [DDA]2PbBr4. Compression at 3 GPa drives the first topochemical polymerization through 1,2 addition, forming a polyene product at room temperature. The reaction is initiated by the mechanical bending of the linear DDA molecule, a mechanism fundamentally different from the 1,4-addition in 3D solids. Importantly, pressure hinders the second 1,2-addition by disfavoring the gauche conformation between the remaining acetylene groups, allowing for the selective formation of polyene versus polyacene products. We characterize the reaction mechanisms and products using spectroscopies (Raman, X-ray photoelectron, ultraviolet-visible), X-ray diffraction and density-functional theory simulations. These results highlight the important role of dimensionality in high-pressure chemistry, and offers a new paradigm for creating low-dimensional functional materials.

Environmental monitoring is becoming increasingly important, primarily in urban areas due to the concentrated levels of human activities. The air sampling device presented is a novel method to sample air which harnesses the power of paper spray ionization paired with the intrinsic advantages of mass spectrometry such as high sensitivity, high selectivity, high throughput, and the ability to monitor multiple compounds at once.