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Full-Text Articles in Engineering

Development Of Nanostructures By Atomic And Molecular Layer Deposition, Andrew P. Lushington Apr 2018

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 ...


Application Of Molecular Layer Deposition For Graphite Anodes In Lithium-Ion Batteries And Porous Thin-Film Materials, Craig L. Langford Jul 2016

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 ...


Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari Apr 2016

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 ...


Nanostructured Carbon Materials For Active And Durable Electrocatalysts And Supports In Fuel Cells, Adam Riese Sep 2015

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 ...


Development Of Novel Nanomaterials Based On Silicon And Graphene For Lithium Ion Battery Applications, Yuhai Hu Sep 2014

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 Apr 2014

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 ...


Nanostructured Tin-Based Anodes For Lithium Ion Batteries With X-Ray Absorption Fine Structure Studies, Dongniu Wang Sep 2013

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 ...


Controlled Synthesis Of One Dimensional Nanostructured Materials And Their Applications As Catalyst Supports In Proton Exchange Membrane Fuel Cells, Mohammad Norouzi Banis Dec 2012

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 ...


Development Of Novel Nanomaterials For High-Performance And Low-Cost Fuel Cell Applications, Shuhui Sun Dec 2011

Development Of Novel Nanomaterials For High-Performance And Low-Cost Fuel Cell Applications, Shuhui Sun

Electronic Thesis and Dissertation Repository

Proton exchange membrane fuel cells (PEMFCs) are promising energy converting technologies to generate electricity by mainly using hydrogen as a fuel, producing water as the only exhaust. However, short life-time and high cost of Pt catalyst are the main obstacles for the commercialization of PEMFCs. In the conventional carbon black supported platinum nanoparticle (NP) commercial catalyst, carbon supports are prone to oxidation and corrosion over time that results in Pt NPs migration, coalescence, even detaching from the catalyst support. In addition, Ostwald ripening of the Pt NPs could also occur due to their high surface energy and zero dimensional structural ...


Nickel-Based Catalysts For Gasification Of Glucose In Supercritical Water, Muhammad Badrul Islam Chowdhury Dec 2010

Nickel-Based Catalysts For Gasification Of Glucose In Supercritical Water, Muhammad Badrul Islam Chowdhury

Electronic Thesis and Dissertation Repository

Gasification of waste biomass to form hydrogen, H2, is a promising new source of green energy; while providing the additional benefit of treating challenging and hazardous waste streams that pollute the environment. Gasification of biomass in supercritical water (SCW) offers an attractive alternative to avoid the energy intensive drying process. In this approach, biomass is hydrolyzed by water into smaller molecules in the presence of a suitable catalyst. This study was aimed at developing an alumina supported nickel based non-noble metal catalyst suitable for biomass gasification in SCW. A lack of detailed characterization on fresh and spent catalysts in SCW ...