Materials Science and Engineering Commons^™

Experimental And Theoretical Analyses Of The Structural, Electronic And Magnetic Properties Of Novel Inverted Core-Shell A-Cr2o3@A-Mxcr2-Xo3-Y (M=Co, Ni, Mn, Fe) Nanoparticles, Mohammad Delower Hossain

MSU Graduate Theses

I used hydrothermal nano-phase epitaxy technique to synthesize well-ordered a-Cr2O3@a-MxCr2-xO3 (M = Co, Ni, Mn, Fe) inverted core-shell nanoparticles (NPs). This resulted in the formation of novel a-MxCr2-xO3 shells having ferromagnetic/ferrimagnetic (FM/FiM) spin ordering and an antiferromagnetic (AFM) a-Cr2O3 core structure. The combined results from Xray diffraction (XRD) and high resolution transmission electron microscoy (HRTEM) provide evidence of the presence of the corundum phase both in the shell and in the core regions. HRTEM results also show a sharp interface exhibiting epitaxial atomic registry of shell atoms over highly ordered core atoms whereas TEM-Energy dispersive spectroscopy analyses show that the …

Molecule Assisted Hydrothermal Synthesis Of Zinc Oxide Nanomaterials With Possible Applicatios In Solar Energy, Austin Major Shearin

MSU Graduate Theses

A molecule assisted hydrothermal synthesis of zinc oxide nanomaterials with L-lysine has been performed to understand the interaction between the biomolecule and the zinc oxide structures during synthesis. The molecule alters the growth kinetics during the formation of the nanomaterials in the hydrothermal reaction. This alters the size and shape of the materials as seen in the scanning electron microscope. X-ray diffraction results confirm the hexagonal Wurtzite structure that zinc oxide forms and indicates no other phases in the nanomaterial. The lattice parameters are not altered, but the atomic percentage of zinc to oxygen within the structure changes as analyzed …

Cell Contraction, De-Adhesion, And Shape Effects Investigated By Cohesive Model With Finite Element Simulations, Margarita Vladimirovna Semenova Petrova

Masters Theses

Cell adhesion is a complex mechanism, and different factors control this process including surface morphology, chemical, and mechanical interactions. These aspects are usually combined to achieve robust adhesion between surfaces. The later stage in bio-adhesion process involves the formation of molecular bonds through diffusion or interpenetration of molecules at the interface. In order to create contact, cells sense their physical environment by applying mechanical forces or responding to them via traction force. The force is transmitted through cell skeleton. However, how this force is transmitted is mostly unknown. Also, there are still many open questions about fracture mechanism in bio-adhesive …

Effect Of Thermal Treatment On High Temperature Deformation Of Alloy Ep-~823, Martin Milburn Lewis

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of this research topic is to determine mechanical properties of Alloy EP-823 and to provide a mechanistic understanding of its sensitivity to both thermal treatment and performance temperature. EP-823 is a leading target material for accelerator-driven waste transmutation applications. Overall, the tensile test results of Alloy EP-823 indicated a general trend of decreasing mechanical performance with an increase in tempering time. An increase in tempering time had a statistically significant inverse relationship with ultimate tensile strength (UTS) and yield strength (YS). An increase in tempering time did not have a significant effect on elongation and reduction in area. …

Synthesis Of Lifepo4/C Cathode Nanomaterials For Lithium-Ion Batteries, Chao Cheng

Theses and Dissertations

Lithium-ion batteries have been widely used for many years. The wide application covers such as smart phones, laptops, digital cameras, MP3 players, and electric vehicles. Lithium-ion batteries have become the most important energy storage device in the future. For lithium-ion batteries, the performance of the cathode materials is one of the most important factors. In recent years, the cathode materials have been widely studied including LiCoO2, LiNiO2, LiMnO2, LiMn2O4 and phosphate etc. Among the olivine structure cathode materials, the LiFePO4 (LFP) displays an excellent electrochemical activity and a chemical stability which ensure a high safety. In order to better improve …

The Effective Use Of Coal Combustion Products (Ccps) In Ashphalt Pavements, Clayton J. Cloutier

Theses and Dissertations

Hot-Mix Asphalt (HMA) is one of the most widely used construction materials. The National Asphalt Paving Association (NAPA) estimated that there are over 2.6 million miles of roadway surfaces paved in the United States and 94% of these roads are paved with asphalt. NAPA also estimates that approximately 550 million tons of asphalt worth over $30 billion a year is produced in the United States. At such a huge production rate, innovative solutions need to be developed so that asphalt pavements last longer and can also reduce the production and maintenance costs. Producing sustainable asphalt materials can provide for improved …

Study Of Ceria Nanoparticles Synthesis And The Performance Of Nano-Ceria Coating For High Temperature Oxidation Resistance In Combustion Atmosphere, Lingke Mao

Theses and Dissertations

Ceria (CeO2 ) nanoparticles were synthesized by the microemulsion method with Bis(2-ethylhexyl) Sulfosuccinate Sodium Salt (AOT) as the surfactant. Stirring speed during synthesis was used to optimize the process and a precipitation process was applied to dilute the surfactant. The prepared ceria nanoparticles were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM). As the result, non-agglomerated and time-stable ceria nanoparticles were obtained with the average particles size of 2-3 nanometers. Stainless steel 316L substrates were coated by a dipping method with the help of a slide motor which provided constant speed and uniform coating layers. Both coated and …

Effects Of Surface Topography And Vibrations On Wetting: Superhydrophobicity, Icephobicity And Corrosion Resistance, Rahul Ramachandran

Theses and Dissertations

Concrete and metallic materials are widely used in construction and water industry. The interaction of both these materials with water and ice (or snow) produces undesirable results and is therefore of interest. Water that gets absorbed into the pores of dry concrete expands on freezing and can lead to crack formation. Also, the ice accretion on concrete surfaces such as roadways can have disastrous consequence. Metallic components used in the water industry undergo corrosion due to contact with aqueous corrosive solutions. Therefore, it is desirable to make concrete water/ice-repellent, and to make metallic surfaces corrosion-resistant.

Recent advances in micro/nanotechnology have …

Nanostructured Organic/Inorganic Semicondutor Photovoltaics: Investigation On Morphology And Optoelectronics Performance, Aruna Wanninayake

Theses and Dissertations

Organic solar cell is a promising technology because of the versatility of organic materials in terms of tunability of their electrical and optical properties. In addition, their relative insensitivity to film imperfections potentially allows for very low-cost high-throughput roll-to-roll processing. However, the power conversion efficiency of organic solar cell is still limited and needs to be improved in order to be competitive with grid parity. This work is focused on the design and characterization of a new organic/inorganic hybrid device to enhance the efficiency factors of bilayer organic solar cells such as: light absorption, exciton diffusion, exciton dissociation, charge transportation …

Coercivity Enhancement And Gamma Phase Avoidance Of Alnico Alloys, Li Zhang

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

The promotion of social progress requires greater levels of energy efficiency, quality and productivity. However, these developments usually come at the cost of the environment. Green technologies such as electric vehicles, wind turbine and solar panels are ironically overshadowed by supply limitations and high prices of rare earth elements. Therefore, it is important to find alternative materials to replace those that contain critical elements. Alnico alloys show high magnetization, high Curie temperature (800°C) and good corrosion resistance, making it one of the best candidates to replace neodymium-based magnets used in electric vehicles.

In this thesis, methods controlling shape anisotropy and …

Recent Progress In Non-Precious Metal Oxygen Reduction Reaction Catalysts With An Encapsulation Structure, Mei-Ling Xiao, Jian-Bing Zhu, Chang-Peng Liu, Jun-Jie Ge, Wei Xing

Journal of Electrochemistry

Platinum-based materials, the state-of-the-art catalysts for fuel cells, suffer from prohibitive costs, limited resources and insufficient durability. Accordingly, tremendous efforts were made in searching for efficient, durable and inexpensive alternatives to precious-metal electrocatalysts for the oxygen reduction reaction (ORR). Transition-metals (Fe, Co)/nitrogen co-doped hybrids, heteroatom (N, P, S, F, et al) doped carbons and composites with transition-metals encapsulated in graphitic layers are reported as the most efficient non-precious metal ORR catalysts. Among the various non-precious metal ORR catalysts, transition-metals encased in graphitic layer catalysts are a novel type of catalysts for ORR with high activity and durability, and thus, the …

Special Issue: Electrocatalyst And Electrocatalysis In Fuel Cells Preface, Zi-Dong Wei

Journal of Electrochemistry

In the last two decades, fuel cells captured worldwide attention as a promising renewable emission-free technology to meet the increasing demand of clean energy for stationary and transportation applications. Currently, platinum (Pt) is the most widely used electrocatalyst for both hydrogen oxidation reaction (HOR) at anode and oxygen reduction reaction (ORR) at cathode. However, the high-cost and scarcity of Pt have become the major challenges for commercialization of fuel cells. To overcome the above mentioned problems, great progress has been made in developing more active electrocatalysts on the basis of Pt-based and Pt-free electro catalysts. For the Pt-based electrocatalysts, composition, …

Mini-Review: Possible Applications Of Scanning Electrochemical Microscopy (Secm) In Characterizations Of Oxygen Reduction Reaction And Oxygen Evolution Reaction, Xing-Xing Chen

Journal of Electrochemistry

Scanning electrochemical microscopy (SECM) has been proved to be a unique technique for combinatorial screening of localized phenomena for different electrocatalysts potentially used in new energy conversion and storage systems. This mini-review provides a brief summary of different SECM working modes, such as direct mode, feedback mode, generation-collection mode, redox competition mode and noise mode, which are especially applied for characterizing the oxygen reactions. Particularly, a series of important development in SECM screening of electrocatalysts for oxygen reduction reaction and oxygen evolution reaction from the author and W. Schuhmann’s group in Germany has been highlighted and overviewed. Finally, some prospects …

Recent Progresses In Molybdenum-Based Electrocatalysts For The Hydrogen Evolution Reaction, Ze-Xing Wu, Jie Wang, Jun-Po Guo, Jing Zhu, De-Li Wang

Journal of Electrochemistry

Electrochemical catalytic production of hydrogen has been considered as a promising and sustainable strategy for clean and renewable energy technologies. Molybdenum-based non noble metal catalysts for the hydrogen evolution reaction have attracted extensive attention due to its effective catalytic performance. In this review, the recent progresses in molybdenum-carbide, phosphide, nitride and sulfide electrocatalysts are presented. In addition, the strategies to improve the catalytic performance are analyzed and the prospects for the future development trends are expected.

Rambling Between "Zhong Yong" And "Catalysis", Zi-Dong Wei

Journal of Electrochemistry

“Zhong Yong” represents a traditional Chinese wisdom, which was first proposed by Confucius and continuously richened by his followers. “Zhong Yong” pursues the balances among all kinds of contradictions, and insists that neither “too much” nor “not enough” is good. For a successful catalyst, on which the adsorption of reactants must be not so strong and not so weak either. On this point of view, there are the same pursuits for “Zhong Yong” and catalysis. In this paper, the author starts his story with a conversation between Confucius and his student, followed by 3 interesting stories happening in the ancient …

Preparation And Performance Of 3d Graphene Type Porous Carbon Employing Nano Fe(Oh)3 As Template For Oxygen Reduction Catalyst, Chong-Yun Sun, Zhong-Fang Li, Xue-Wei Lu, Xi-Zhan Zhong, Yu-Rong Liu

Journal of Electrochemistry

The 3D graphene type porous carbon was prepared using coal tar pitch as carbon source and nano Fe(OH)₃ as template. Optimal conditions for the catalytic oxygen reduction performance were determined as: the mass ratio of coal tar, nano Fe(OH)₃ and KOH is 6:8:4; the pyrolysis temperature is 800 ^oC. SEM images show that the products have uniformly porous structure. TEM images demonstrate that the products are porous with foam shapes. HRTEM images further indicate that the products have formed several-layers 3D graphene structure, which are also supported by XRD and Raman data, and the pore size mainly …

Nitrogen, Fluorine Co-Doped Silk-Derived Carbon For Electrochemical Oxygen Reduction With High Performance In Alkaline Solution, Fang-Fang Liu, Hong-Liang Peng, Shi-Jun Liao

Journal of Electrochemistry

A high-performance, doped carbon-based catalyst was synthesized by pyrolyzing hydrothermally treated silkworm cocoon. The effects of preparation conditions and fluorine promotion on various catalysts’ performance were investigated. The catalyst prepared under optimal conditions and doped with nitrogen and fluorine possessed the high specific surface area of more than 1000 m²•g^-1 and contained 3.5 and 7.3% (by mass, the same below) N and F, respectively. The activity of the catalyst toward oxygen reduction reaction in an alkaline medium was comparable to that of commercial Pt/C, showing both superior tolerance to methanol poisoning and better durability. Doping with fluorine …

Dynamic Simulation Of Oxygen Reduction Reaction In Pt/C Electrode For Proton Exchange Membrane Fuel Cells, Li Shang, Zhou Fen, Chen Lei, Pan Mu

Journal of Electrochemistry

It is an urgent need to reduce the Pt loading in electrode for practical fuel cell applications worldwide. Herein, we theoretically investigate the oxygen distribution, generated current, and minimum Pt loading of Pt/C electrode for practical applications based on kinetic model of oxygen reduction reaction. The results indicate that with increasing electrode effective thickness to 40 mm, serious concentration polarization is expected for Pt/C electrode. To generate a power density of 1.4 W•cm^-2 (2.1A•cm^-2 @0.67 V) for fuel cell, the cathode catalyst layer thickness in PEMFC should be as thin as 3 mm. The minimum Pt loading will …

Multi-Scaled Carbon Supported Platinum As A Stable Electrocatalyst For Oxygen Reduction Reaction, Yu-Ping Li, Lu-Hua Jiang, Su-Li Wang, Gong-Quan Sun

Journal of Electrochemistry

The stability of carbon supports is essential for electrocatalysts of fuel cells. Herein, the mesoporous carbon with the high graphitic degree (highly graphitic mesoporous carbon, HGMC) was synthesized by using resorcinol as the carbon precursor, SiO2 as the templates and urea as the reducing agent. The as-prepared HGMC was characterized by XRD, Raman spectroscopy, TEM, N2 adsorption. The stability of HGMC was evaluated by mimicking the start-up/shut-down conditions of fuel cells in a three-electrode system referring to the NREL standard. The obtained HGMC is of moderate surface area (187.4 m²•g^-1) and is chemically stable under potentiodynamic …

Recycling Mf Solid Waste Into Mesoporous Nitrogen-Doped Carbon With Iron Carbide Complex In Graphitic Layers As An Efficient Catalyst For Oxygen Reduction Reaction, Can-Yun Zhao, Lin Huang, Yong You, Ying-Fang Yao, Xiao-Gang Su, Hong Wan, Jian-Guo Liu, Cong-Ping Wu

Journal of Electrochemistry

Nitrogen-doped carbon materials with iron ions are known as catalytic growth agents for the oxygen reduction reaction (ORR) in fuel cells, but the design and synthesis of high-performance and low-cost catalysts still remain a significant challenge. Herein, we present a cost-effective approach to dispose of MF solid waste as the precursor for the synthesis of MCFes catalyst with the favorable structure features such as the high specific surface area, abundant active sites and suitable pore structure. The results showed that the MCFe-10/10/2 had specific surface area as high as 780.7 m²•g^-1 and high efficient catalytic activity comparable …