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This dissertation presents studies electrodeposited MoS2 and metal-doped MoS2 thin films, and their performance for energy storage, catalysis, and biosensor applications. Ni-doped MoS2 thin films were fabricated by electrodeposition from electrolytes containing both MoS42- and varying concentrations of Ni2+, followed by annealing at 400 ºC for 2 h in an Ar atmosphere. The film resistivity increased from 11.3 µΩ-cm for un-doped MoS2 to 32.8 µΩ-cm for Ni-doped MoS2 containing 9 atom% Ni. For all Ni dopant levels studied, only the x-ray diffraction (XRD) pattern expected for MoS2 is observed, with the average grain size increases with increasing Ni content. Ni-doped MoS2 thin films were tested for their activity towards the hydrogen evolution reaction (HER) in 0.5M H2SO4. Tafel equation fits reveal that the catalytic activity for HER, as measured by the exchange current density, increases up to 6 atom% Ni, and then decreases slightly for 9 atom% Ni. Ni-doped MoS2 thin films were also tested in 1.0 M Na2SO4 for use within electrochemical supercapacitors, and the capacitance per unit area increases by 2-3x for 9 atom% Ni-doped MoS2 relative to un-doped MoS2. The highest specific capacitance obtained for Ni-doped MoS2 during galvanostatic charge-discharge measurements is ~300 F/g

Carbon based semiconductors such as conjugated polymer or single walled carbon nanotubes (SWNT) are promising materials for use next generation printable and wearable electronics. Thin film transistors (TFTs) are often viewed as a building block for more complex electronic device, however, lack of proper characterization of these devices using these novel carbon-based materials is preventing their large-scale adoption. This thesis has two sections; in the first section I explored and improved a novel electrical model originally developed for organic or polymer-based TFTs called the organic virtual source emission diffusion model (OVSED). I improved this model by adding a variable contact resistance parameter and effective gate voltages. I then found better agreement between model and experimental data using this improved OVSED model against the conventional MOSFET based models: the SH and Y-function models, for poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)) based OTFTs. The new model proved to be an efficient tool for benchmarking polymer based TFTs and provided an efficient way to characterize and reduce contact resistance in the devices. In the second section, I explore the effect of light on a series of conjugated polymer wrapped SWNT TFTs. A structure property relationship was established between the wrapping polymer structure and the exposure wavelength intensity. We demonstrated that SWNT TFTs can act as photodetectors after an initial light soak. Finally, we further characterized the SWNT TFTs using our OVSED model validating the observed structure property relationship. Overall this thesis demonstrates steps towards proper characterization of emerging carbon based semiconductors used in TFTs. -- Les semi-conducteurs à base de carbone, tels que les polymères conjugués ou les nanotubes de carbone à paroi simple (SWNT), sont des matériaux prometteurs pour la prochaine génération d'appareils électroniques imprimables et portables. Les transistors à couche mince (TFT) sont souvent considérés comme un élément de base pour des dispositifs électroniques plus complexes, mais la caractérisation incorrecte de ces dispositifs utilisant ces nouveaux matériaux à base de carbone empêche leur adoption à grande échelle. Cette thèse comporte deux sections ; dans la première, j'ai exploré et amélioré un nouveau modèle électrique développé à l'origine pour les TFT organiques ou à base de polymères, appelé le modèle de diffusion d'émission de source virtuelle organique (OVSED). J'ai amélioré ce modèle en ajoutant un paramètre de résistance de contact variable et des tensions de grille effectives. J'ai ensuite constaté une meilleure concordance entre le modèle et les données expérimentales en utilisant ce modèle OVSED amélioré par rapport aux modèles conventionnels basés sur les MOSFET : les modèles à fonction SH et Y, pour les OTFT à base de poly{[N,N'-bis(2-octyldodecyl)-naphtalène-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophène)} (P(NDI2OD-T2)). Le nouveau modèle s'est avéré être un outil efficace pour comparer les TFT à base de polymères et a fourni un moyen efficace de caractériser et de réduire la résistance de contact dans les dispositifs. Dans la deuxième partie, j'explore l'effet de la lumière sur une série de TFT à base de SWNT enveloppés de polymères conjugués. Une relation structure-propriété a été établie entre la structure du polymère enveloppant et l'intensité de la longueur d'onde d'exposition. Nous avons démontré que les SWNT TFT peuvent agir comme des photodétecteurs après une imprégnation initiale de lumière. Enfin, nous avons caractérisé les SWNT TFT à l'aide de notre modèle OVSED en validant la relation structure-propriété observée. Dans l'ensemble, cette thèse démontre les étapes vers une caractérisation appropriée des semi-conducteurs émergents à base de carbone utilisés dans les TFT.

Access to clean water is one of the world's greatest concerns. Because 97% of global water resources are seawater, desalination via reverse osmosis (RO) membrane process has become a vital technology to obtain drinkable water. At the same time, the discharge of industrial waste effluents containing heavy metal ions to the available water resources (seawater and brackish water) without adequate pre-treatment is a major cause of water pollution. Heavy metal rejection using nanofiltration (NF) membrane process is a recognized water treatment methodology. Thin-film nanocomposite (TFN) membranes have shown vast performance enhancement using both RO and NF processes. However, TFN membrane fabrication has been limited due to poor dispersion of the nanoparticles in the polyamide (PA) layer of the membrane, and the leaching of the often-hazardous nanoparticles from the TFN membranes. For various reasons such as their dispersibility in aqueous media, safety, high aspect ratio, and functionality, cellulose nanocrystals (CNCs) are an ideal nanoparticle for inclusion in TFN membranes. Because of their hydrophilicity, CNCs have more commonly been dispersed in the aqueous monomer solution during PA interfacial polymerization. In this thesis, we investigated two different CNC modification routes to improve CNC dispersion within the trimesoyl chloride (TMC)/n-hexane (non-aqueous) monomer solution. In one case, we acetylated the CNCs (ACNCs) using a straightforward, efficient, solvent-free method to achieve a more uniform CNC dispersion in the PA layer. The resulting ACNCs were less hydrophilic, which allowed increased nanoparticle loading and improved dispersion in the PA layer. In an RO desalination process, compared to unmodified CNC-TFN membranes, the NaCl rejection of the ACNC-TFN membranes remained stable (at 98-99%) up to a 0.4 wt% loading, while water permeability increased by up to 40%. For the second case, we synthesized L-cysteine functionalized CNCs (CysCNCs) and incorporated them into the PA layer for testing in an NF wastewater treatment process. The amine functional groups of L-cysteine covalently bonded with the acyl chloride groups of the TMC monomer. This resulted in improved nanoparticle dispersion but could also have prevented nanoparticle leaching. Moreover, because L-cysteine contains strong chelating groups, their inclusion in the PA layer led to improved heavy metal rejection. A loading of 0.1 wt% CysCNCs in the TFN membranes provided high rejection of both copper and lead ions, 98.1 and 95.2%, respectively. The CysCNCs were also evaluated in an NF desalination process resulting in a 40% increase in water permeability with almost no decline in Na₂SO₄ (97-98%), MgCl₂ and NaCl rejection. The modified CNCs enabled us to overcome the water permeability/selectivity trade-off in CNC-TFN membranes for both RO and NF membrane desalination. Finally, we developed an experimental protocol to investigate the effect of the adsorption of heavy metal ions (if any) on the performance of thin film composite (TFC) and TFN membranes in NF. We confirmed that adsorption occurred, and the equilibrium capacity of the membranes was reached after 8 - 12 h of the experiment. Despite reaching the equilibrium capacity, the water permeability and heavy metal rejection remained at their highest values. This led to the conclusion that the adsorbed heavy metals altered the membrane surface, thereby improving the performance of both TFC and TFN membranes. The ability to modify CNCs enables one to achieve a controlled range of hydrophilicity/ hydrophobicity. This allows one to fine-tune CNC compatibility with the TMC/n-hexane non-aqueous monomer solution and enable improved dispersion in the PA layer, eventually leading to improved TFN membrane performance for both RO and NF processes.

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The need for miniaturized, portable devices to separate and detect unknown compounds has greatly multiplied, leading to an increased interest in microfluidics. Total integration of the detector and pump are necessary to decrease the overall size of the microfluidic device. Using previously developed thin film technologies, an electroosmotic flow (EOF) pump was incorporated in a microfluidic liquid chromatography device. An EOF pump was chosen because of its simple design and small size. EOF pumps fabricated on silicon and glass substrates were evaluated. The experimental flow rates were 0.19-2.30 microliters/minute for 40-400 V. The theoretical pump efficiency was calculated along with the generated mechanical power by various pump shapes to elucidate more efficient pump designs. To better understand the EOF on plasma enhanced chemical vapor deposition (PECVD) silicon dioxide, the zeta potential was investigated. PECVD oxide is amorphous and less dense than thermal silicon dioxide, which slightly changes the zeta potential. Zeta potentials were found for pH values from 2.6 to 8.3. Also, surface defects that affect the zeta potential were observed, and procedures to detect and prevent such defects were proposed. Finally, surface modifications to the microfluidic device were attempted to demonstrate that thin film EOF pumps can be used in the liquid chromatographic separation of mixtures. The microfluidic separation channel was coated with chlorodimethyloctadecylsilane, however, due to problems with channel filling and reservoir adhesives, separation was not achieved. The use of new adhesives and external pumps were proposed to resolve these problems for future testing. Also new methods to combine EOF pumps with microfluidic channels and on-chip detectors were suggested.

Approximately 7.5 million people suffer from voice disorders in the United States. Previous studies indicate that the quality of the fluid layer that coats the vocal folds appears to be different for people with voice disorders than for people whose voice is considered normal. These studies suggest that the composition and/or physical properties of the fluid layer may contribute to voice disorders. Despite these findings, little research has been undertaken to investigate the role of the fluid layer on voice, and in almost all cases, the fluid layer is considered to be insignificant. The purpose of this research was to investigate the role of the fluid layer and the potential it may have to influence voice production; particularly, to identify some aspects of the fluid layer that have the potential to contribute to voice disorders. In order to investigate the potential significance of the effects of a fluid layer on vocal fold operation, an existing lumped model was modified to incorporate the Newtonian squeeze-flow equation as a fluid model during the colliding portion of the oscillatory cycle. Results indicated that thicker films produced more significant deviations from the case with no fluid layer. Experimental testing was performed to validate existing analytical equations for squeezing flow of Newtonian and non-Newtonian fluids confined between parallel axisymmetric plates. Based on available published data on the rheological properties of the fluid layer found on the surface of the vocal folds, several fluids with a range of fluid properties were selected. Reasonable agreement was found for much of data collected for the Newtonian fluid cases within measurement tolerances. For the non-Newtonian cases, the constitutive equation was found to be in poor agreement with the measured physical characteristics of the selected non-Newtonian fluids. A summary of the collected experimental data is provided so that it can be used in for validation and comparison in future research. A preliminary computational model based on the classical two-mass vocal fold model was implemented which incorporated squeezing effects of a thin Newtonian film of fluid on the surface of the vocal folds. Results indicated that the fluid layer may not be insignificant, although further tests and modeling are required. Finally, different fluids were applied to a physical model of the vocal folds and measurements were taken to determine the effects of the application of fluid. The results showed significant changes in the vocal fold model response that indicated the fluid layer affects vocal fold operation in important ways. Some of the changes in response could not be attributed solely to the fluid layer. Suggestions regarding future work with physical model testing are given which may help clarify the effects of a fluid layer on vocal fold flow-induced vibration.