Engineering Commons^™

Development Of Nanostructures By Atomic And Molecular Layer Deposition, Andrew P. Lushington

Electronic Thesis and Dissertation Repository

Atomic layer deposition (ALD) is a thin film deposition technique that has a rich history of being an enabling technique. This vapor phase deposition process can produce a variety of thin films and nanostructures. ALD is based on sequential, self-limiting reactions and provides angstrom level control over film growth. Furthermore, ALD allows for conformal deposition on high-aspect ratio structures and can provide tunable film composition. As nanotechnology marches forward, the development of nanomaterials has significantly advanced. Additional functionality can be imparted to nanomaterials by using surface modification techniques. Given the advantages of ALD, this technique has become a powerful tool …

Combustion Of Nanocomposite Thermite Powders, Ian Monk

Dissertations

This work investigates combustion of nanocomposite thermite powders prepared by arrested reactive milling (ARM). The focus is on how ARM as a top-down approach to nano-thermite building generating fully-dense nanocomposite particles with dimensions of 1-100 µm affects the rates and mechanism of their combustion. A variety of thermites are milled using both aluminum and zirconium as fuels combined with several oxidizers (WoO₃, MoO₃, CuO, Fe₂O₃, and Bi₂O₃). The powders are ignited using both an electrostatic discharge (ESD) and a CO₂ laser beam.

A range of parameters vary …

Nonlinear Coupled Effects In Nanomaterials, Sia Bhowmick

Theses and Dissertations (Comprehensive)

Materials at the nanoscale have different chemical, structural, and optoelectrical properties compared to their bulk counterparts. As a result, such materials, called nanomaterials, exhibit observable differences in certain physical phenomena. One such resulting phenomenon called the piezoelectric effect has played a crucial role in miniature self-powering electronic devices called nanogenerators which are fabricated by using nanostructures, such as nanowires, nanorods, and nanofilms. These devices are capable of harvesting electrical energy by inducing mechanical strain on the individual nanostructures. Electrical energy created in this manner does not have environmental limitations. In this thesis, important coupled effects, such as the nonlinear piezoelectric …

Modeling Of Thermally Aware Carbon Nanotube And Graphene Based Post Cmos Vlsi Interconnect, K M Mohsin

LSU Doctoral Dissertations

This work studies various emerging reduced dimensional materials for very large-scale integration (VLSI) interconnects. The prime motivation of this work is to find an alternative to the existing Cu-based interconnect for post-CMOS technology nodes with an emphasis on thermal stability. Starting from the material modeling, this work includes material characterization, exploration of electronic properties, vibrational properties and to analyze performance as a VLSI interconnect. Using state of the art density functional theories (DFT) one-dimensional and two-dimensional materials were designed for exploring their electronic structures, transport properties and their circuit behaviors. Primarily carbon nanotube (CNT), graphene and graphene/copper based interconnects were …

Advanced Purification And Direct-Write 3d Nanoprinting Via Focused Electron Beam Induced Deposition, Brett Bloxton Lewis

Doctoral Dissertations

This dissertation addresses three difficulties with focused electron beam induced deposition preventing broader application; purity, spatial control, and mechanical characterization.

Focused electron beam induced deposition (FEBID) has many advantages as a nanoscale fabrication tool. It is compatible for implementation into current lithographic techniques and has the potential to direct-write in a single step nanostructures of a high degree of complexity. FEBID is a very versatile tool capable of fabricating structures of many different compositions ranging from insulating oxides to conducting metals.

Due to the complexity of the technique and the difficulty in directly measuring many important variables, FEBID has remained …

Mechanical Characterization Of Polymer Concrete With Nanomaterials, Alaeddin Douba

Civil Engineering ETDs

Nanomaterials are defined by those whose characteristic length scale lies within the nanometer scale. Their extreme dimension achieves extraordinary mechanical properties superior to other micro and macro additives. The introduction of nanotechnology to Civil Engineering utilizes low volume inclusions of nanomaterials to alter the properties of conventionally used bulk materials. Polymer Concrete (PC) where epoxy polymer binders replace cement binders, has become a common repair material among many other application and often can be considered an alternative to Portland cement concrete (PCC). PC is often used in bridge deck overlays, manholes, machine foundations and repairs. Its diverse chemical composition and …

Novel Design Of Nanostructured Material For Advanced Energy Conversion And Storage Devices, Wangwang Xu

LSU Master's Theses

Nowadays, the fast-increasing energy demand for efficient, sustainable and environmentally-friendly energy storage devices remains a significant and challenging issue. Lithium ion batteries (LIBs) have been widely used as commercial energy devices in portable electronics and also shown great promise in upcoming large scale applications due to their advantages of environmental safety, efficiency in energy delivering and light weight. However, due to their limited capacity, energy densities and cycle ability, LIBs still need further improvement to expand their applications to a larger field, especially electric vehicle (EVs) and hybrid electric vehicles (HEVs), in which energy storage devices with large capacity and …

Nanomaterials For Solar Distillation Technology, Jack Warren Stoddard Cheney

UNLV Theses, Dissertations, Professional Papers, and Capstones

Water is the most important resource for mankind. Yet, 97% of the earth’s surface water is seawater in the oceans and only 3% is fresh water in ground water. Therefore, different kinds of water desalination and treatment technologies have been developed, and water distillation is a basic process of evaporating water in order to leave behind impurities such as minerals, pollutants, and other contaminants. Although distillation is known as an effective water treatment process that removes many kinds of bacteria and inorganic chemicals and heavy metals, a large amount of conventional energy and non-renewable resources are consumed for this process. …

Application Of Molecular Layer Deposition For Graphite Anodes In Lithium-Ion Batteries And Porous Thin-Film Materials, Craig L. Langford

Electronic Thesis and Dissertation Repository

With climate change occurring because of greenhouse gas emissions, the demand for emission free transportation has led to the development of electric vehicles. Improving the batteries’ cycling stability, capacity and safety have been the leading challenges to compete with gasoline and diesel engines. With advances in thin-film deposition techniques via atomic and molecular layer deposition, ultrathin films can be deposited to control the surface chemistry of the battery’s active materials. This thesis aims to understand two main aspects of molecular layer deposition. First, how it can influence solid electrolyte interface formation on the graphite surface during cycling in a lithium-ion …

Custom Engineered Nanomaterials For Energetics And Energy Applications, Ani Abraham

Dissertations

Recent interest in reactive material has shifted to more custom formulations targeting specific applications. In this work, preparation and characterization of nanomaterials used for several energetics and energy applications are addressed.

The main challenge of this effort is to design and prepare nanomaterials which have significant improvements associated with combustion dynamics, reaction rates, sensitivity, biocidal effectiveness, moisture stability, and are environmentally safer over the existing energetics. Nanomaterials that are used to defeat stockpiles of chemical and biological weapons, modify ionosphere properties for transmission of optical and radio signals, and for energy storage are prepared under room or cryogenic temperatures via …

Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari

Electronic Thesis and Dissertation Repository

This thesis explores the synthesis of metal oxide 1-D nanowires using a sol-gel method in supercritical carbon dioxide (sc-CO₂), as an environmental friendly enabling solvent. Porous nanowires were synthesized and their performance was tested in dye sensitized solar cell and sacrifical hydrogen production. Titanium isopropoxide (TIP) was used as a precursor for titania synthesis while copper, bismuth and indium were examined as dopants, respectively. The sol-gel reactions were catalyzed by acetic acid in CO₂ at a temperature of 60 °C and pressure of 5000 psi. It was observed that acetic acid/monomer ratio > 4 produced nanowires while a …

Bio-Inspired Synthesis Of Nanostructured Materials On Substrates For Environmental And Energy Applications, Xinghua Meng Meng

Wayne State University Dissertations

It is still a challenging task to develop simple methods for facile synthesis of functional nanostructures on substrates under mild conditions without using expensive instruments. We have successfully developed a bio-inspired method using simple diaphragm-assisted system to synthesize functional nanostructures on various substrates under mild conditions. We have systematically studied the effects of experimental parameters on the formation of nanostructures under controlled conditions. The fundamental mechanism involved has been systematically studied and revealed. By growing the unique networks of nanostructures on a piece of substrate, a double-rough surface, with structures at both nanoscale and microscale, has been achieved, showing interesting …

Copper And Zinc Oxide Composite Nanostructures For Solar Energy Harvesting, Fei Wu

McKelvey School of Engineering Theses & Dissertations

Solar energy is a clean and sustainable energy source to counter global environmental issues of rising atmospheric CO2 levels and depletion of natural resources. To extract useful work from solar energy, silicon-based photovoltaic devices are extensively used. The technological maturity and the high quality of silicon (Si) make it a material of choice. However limitations in Si exist, ranging from its indirect band gap to low light absorption coefficient and energy and capital intensive crystal growth schemes. Therefore, alternate materials that are earth-abundant, benign and simpler to process are needed for developing new platforms for solar energy harvesting applications.

In …

Nanostructured Carbon Materials For Active And Durable Electrocatalysts And Supports In Fuel Cells, Adam Riese

Electronic Thesis and Dissertation Repository

Meeting the energy demands of the future will require a breadth of technologies and materials for generating and converting electricity. Increasing activity and reducing costs of electrocatalysts for fuel cells is among the most important challenges for the technology. With advances in nanomaterials there has been increased interest in creating novel catalysts with both high activity and excellent long-term durability. This thesis aims to understand how modification of nanostructured carbons can be used to improve the activity and durability of catalysts and supports for the oxygen reduction reaction (ORR). Using an integrating approach to synthesis, characterization, and electrochemical testing, it …

A High Pressure Cell For Spark Plasma Sintering, Justin Robert Carmichael

Masters Theses

Many nanostructured materials have been shown to have performance gains strongly dependent on the grain size in the material. Nanostructured thermoelectric materials for instance have found great performance increases through reduction of the grain sizes, due mostly to the scattering of phonons while retaining a good electrical conductivity. Other such examples abound where the grain size plays an important role in the performance of the material, including magnetic materials, proton fuel cell membranes, or simply improving the mechanical properties of a system through the Hall-Petch relationship.

A considerable amount of effort has been applied into reducing the grain size of …

Enhancement Of The Performance Of Gaas Based Solar Cells By Using Plasmonic, Anti-Reflection Coating And Hydrophobic Effects, Yahia Fayiz Makableh

Graduate Theses and Dissertations

Investigation of renewable energy resources is gaining huge momentum in recent years due to the limited fossil fuels, and their detriment impact on the environment. Solar energy is promising to meet the increased energy demand. In order to achieve this goal, solar energy has to be harvested efficiently at low cost. Therefore, higher efficiency solar cells are the primary focus of research worldwide. Photovoltaics based on InAs/GaAs intermediate band solar cells and their device performance enhancements are investigated in this dissertation. The device enhancement is carried out by surface modification methods. The dissertation work is inspired by the need of …

Preparation And Characterization Of Copper-Doped And Silver-Doped Titanium Dioxide Nano-Catalysts For Photocatalytic Applications, Haya Abdel Ra'ouf Ahmed

Theses

The goal of this work was to improve the performance of TiO₂ nanomaterials by increasing their optical activities by shifting the onset of the response from the UV to the visible-light region. Among the several ways to achieve this goal, doping TiO₂ nanomaterials with other elements (e.g. metals) was selected to narrow the band gap and enhance the optical properties of TiO₂ nanomaterials. In this work, we have prepared Cu-doped TiO₂ nano-catalysts, characterized them and studied their properties, and the optical ones in particular. The Ag-doped TiO₂ catalyst was prepared by the sol-gel method while …

Novel Nanostructured Materials For Solar Fuel Production And Advanced Rechargeable Batteries, Cunyu Zhao

Theses and Dissertations

Non-renewable fossil fuels are the major sources to meet the energy, electricity and transportation demands of today's world. The over consumption of fossil fuels will lead to the increasing energy crisis and disastrous effects such as air pollution, global warming etc.

The primary greenhouse gas is CO2 mainly emits from the combustion of fossil fuels. Photocatalytic reduction of CO2 using sunlight as the energy input is a promising way to reduce CO2 level in the atmosphere and in the meantime produce alternative fuels such as CO, methane, methanol, etc. Among the various photocatalyst materials reported, nanomaterial TiO2 is the most …

Development Of Novel Nanomaterials Based On Silicon And Graphene For Lithium Ion Battery Applications, Yuhai Hu

Electronic Thesis and Dissertation Repository

Electrochemical energy storage is one of the important strategies to address the strong demand for clean energy. Rechargeable lithium ion batteries (LIBs) are one of the typical electrochemical devices and have been used in a great number of areas. Now, the challenge for the LIB research is to make the batteries carry higher energy density so as to fulfill the demand of the emerging markets, particularly, electric vehicles and portable smart electronics. In this regard, the present commercial anode material can not meet this requirement. Much effort is being made toward either exploring new morphologies of carbon materials or searching …

Antibacterial Studies On Titania Polyurethane Nanocomposite Coatings, Koosha Azhie

Electronic Thesis and Dissertation Repository

While temporary disinfection of a surface is possible with the help of strong cleaners, tremendous interest exists for the control of microorganisms on surfaces by effective, durable antimicrobial coatings. There is a wide spectrum of potential applications for antibacterial coatings, spanning from industrial surface coatings to biomedical applications, where sterile conditions are crucial. This work examined the synthesis of the functionalized 2,2-Dimethylolpropionic acid - nanotitanium dioxide (DMPA-nTiO₂) monomer. Moreover, functionalized nanotitanium dioxide/polyurethane (nTiO₂/PU) composite coatings were prepared using the above mentioned functionalized monomer. The distribution of nTiO₂ in the polymer matrix was enhanced by monomer …

An Atomic Force Microscopy Nanoindentation Study Of Size Effects In Face-Centered Cubic Metal And Bimetallic Nanowires, Erin Leigh Wood

Graduate College Dissertations and Theses

The enhancement of strength of nanoscale materials such as face-centered cubic metal nanowires is well known and arises largely from processes mediated by high energy surface atoms. This leads to strong size effects in nanoscale plasticity; ,smaller is stronger. Yet, other factors, such as crystalline defects also contribute greatly to the mechanical properties. In particular, twin boundaries, which are pervasive and energetically favorable defects in face-centered cubic metal nanowires, have been shown to greatly enhance the strength, furthermore this increase in strength has been shown to be directly influenced by the twin density. However, attempts to control the …

Nanostructured Tin-Based Anodes For Lithium Ion Batteries With X-Ray Absorption Fine Structure Studies, Dongniu Wang

Electronic Thesis and Dissertation Repository

The practical applications of lithium ion batteries are highly dependent on the choice of electrodes, where boosting the materials innovations to design and achieve high capacity, excellent cycling performance, rate capability, low-cost and safe electrode materials provide the best solution. Based on this, tin-based anodes have gained great attention due to its high theoretical capacity, low cost and nontoxic nature to environment. Nevertheless, it undergoes significant volume variation(259%)during the operation of the battery, leading to pulverization and significant capacity fade. Thus, the practical application of tin-based anodes is still quite challenging. This thesis tackles issues related to tin-based anodes. It …

Novel Bimetallic Plasmonic Nanomaterials, Ritesh Sachan

Doctoral Dissertations

Plasmonic nanomaterials have attracted a lot of attention recently due to their application in various fields such as chemical and biological sensing, catalysis, energy harvesting and optical devices. However, there is a need to address several outstanding issues with these materials, including cost-effective synthesis, tunability in plasmonic characteristics, and long term stability. In this thesis, we have focused on bimetallic nanoparticles (NPs) of Ag and Co due to their immiscibility as well as their individual properties. First, a pulsed laser induced dewetting route was used to synthesize Ag-Co bimetallic plasmonic NPs. An synthesis parameter space was derived to show the …

Tuning The Performance Of Nanocarbon-Based Gas Sensors Through Nanoparticle Decoration, Shumao Cui

Theses and Dissertations

Tin dioxide (SnO₂) is a well–known gas sensing material, but it becomes sensitive only at elevated temperatures (e.g., above 200 °C). Nanoparticles (NPs) combined with nanocarbons, such as carbon nanotubes (CNTs) and graphene, form a new class of hybrid nanomaterials that can exhibit fascinating gas sensing performance due to tunable electron transfer between NPs and nanocarbons induced by gas adsorption. Indeed, sensors made of SnO₂ NPs&ndascoated CNTs have shown outstanding room–temperature sensing performance to various gases, including those that are undetectable by either SnO₂ or CNTs alone.

The objectives of this dissertation study are to synthesize …

Influence Of Media Size And Flow Rate On The Transport Of Silver Nanoparticles In Saturated Porous Media: Laboratory Experiments And Modeling, Travis J. Meidinger

Theses and Dissertations

Silver nanoparticles (AgNPs) are widely produced and used. Because of their potential toxicity and the possibility of their release into the environment, it is important to understand the factors involved in their transport; particularly how they may move in groundwater, which is a potential pathway to human and environmental receptors. By passing a solution of 15 mg/L AgNPs with an average size of 17 nm through sand-filled glass columns, this study looks at the physical effects of flow rate and media size on transport. Three different sand sizes ( 0.074, 0.21-0.297, and 0.4-2.0mm) were used, as well as two different …

Nanoscale Electrochemistry By In-Situ Transmission Electron Microscopy, Qi Gao

Dissertations, Master's Theses and Master's Reports - Open

Nanoscale research in energy storage has recently focused on investigating the properties of nanostructures in order to increase energy density, power rate, and capacity. To better understand the intrinsic properties of nanomaterials, a new and advanced in situ system was designed that allows atomic scale observation of materials under external fields. A special holder equipped with a scanning tunneling microscopy (STM) probe inside a transmission electron microscopy (TEM) system was used to perform the in situ studies on mechanical, electrical, and electrochemical properties of nanomaterials. The nanostructures of titanium dioxide (TiO2) nanotubes are characterized by electron imaging, diffraction, and chemical …

Synthesis And Characterization Of One Dimensional Boron-Based Nanomaterials, Rui Li

Theses and Dissertations

One dimensional (1D) metal borate and boride nanomaterials have attracted tremendous attention due to their good chemical inertness, high-temperature stability, excellent mechanical properties, and low thermal expansion coefficient.

Beta-BaB2O4 (BBO) is a well-known nonlinear optical material with a high second-order nonlinear susceptibility, wide transparency range, and high damage threshold. Using a low temperature, organic-free hydrothermal technique, single-crystalline barium polyborate Ba3B6O9(OH)6 (BBOH) nanorods were synthesized. It was found that BBO nanospindles can be achieved by annealing the BBOH nanorods at a relatively low temperature of 810 oC. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques were …

Controlled Synthesis Of One Dimensional Nanostructured Materials And Their Applications As Catalyst Supports In Proton Exchange Membrane Fuel Cells, Mohammad Norouzi Banis

Electronic Thesis and Dissertation Repository

Nanomaterials have attracted significant interest in the past decade due to their unique structure and properties compared to their bulk counterparts. Nanomaterials-based solutions can address challenges in various technologies such as proton exchange membrane fuel cells (PEMFCs). PEMFC is an innovative energy conversion technology to directly convert chemical energy to electrical energy by using hydrogen as fuel. However, the current PEMFC system still faces significant technological roadblocks which have to be overcome before the system can become economically viable. A major impediment to the commercialization of PEMFC is the high cost of materials and manufacturing and stability, which is primarily …

Functionalized Nanoparticles As Removable Coatings For Reverse Osmosis Membranes, Megan Smith

All Theses

Reverse osmosis (RO) desalination is increasingly used to produce potable water throughout the world. Despite their promising abilities, membrane filtration processes are limited by fouling. Fouling is a broad term for organics, inorganics, colloids and organisms that interact physically, chemically, or biologically with the membrane surface, resulting in reduced flux and shortened membrane lifespan. There is potential to create a snakeskin-like barrier between the membrane and foulants by electrostatically binding a coating material to the membrane that can be released by pH manipulation, removing foulants in the process. The feasibility of using functionalized nanoparticles as removable adsorptive coatings on RO …

Characteristics And Functionalities Of Natural And Bioinspired Nanomaterials, Lijin Xia

Doctoral Dissertations

Green nanoscience is a rapidly emerging field that aims to achieve the maximum performance and benefits from nanotechnology, while minimizing the impact on the environment. In this study, several methods for the green nanomanufacturing of biomedically important nanomaterials, specifically through the use of natural plants, have been extensively investigated. It was found that natural nanomaterials are inherent within plants, and can be further manipulated for potential biomedical applications. In addition, the metabolites and reductive capacity of plant extracts can be used to synthesize metallic nanoparticles with advantages over semi-conductor based nanomaterials. Nanoparticles were found to exist in the extracts produced …