Engineering Commons^™

Synthesis Of Porous Carbon Nanosheets And Its Application In Sodium-Ion Battery, Jing-Fei Zhang, Jing Lu, Xiao-Yu Yang, Yun-Di Huang, Lin Xu, Dong-Mei Sun, Ya-Wen Tang

Journal of Electrochemistry

Owning to sodium’s high abundance, relatively low cost, similar chemical properties to Li and very suitable redox potential of E0(Na+/Na) = -2.71 V versus SHE which is only 0.3 V above that of lithium, rechargeable sodium ion battery hold much promise as potential alternatives to current lithium ion batteries for energy storage applications. Carbon material is regarded as the most promising anode candidate for sodium ion battery. Particularly, carbon nanosheet with porous structure and high conductivity is expected to have improved sodium ion storage properties. In this paper, we present a two-step pyrolysis-based method for facile synthesis of porous carbon …

Intercalation Of Clo4- Into Hopg Investigated By Ec-Stm, Xiao-Yan Hu, Alice Aliwowe, Jia-Wei Yan, Bing-Wei Mao

Journal of Electrochemistry

The electrochemical intercalation and surface morphology of highly oriented pyrolytic graphite (HOPG) electrode in 2 mol•L^-1 HClO₄ were studied by in situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV). Based on the step-height changes observed before and after the intercalation, the effects of different step sites on intercalation are compared. The feasibility, reversibility and speed of intercalation are discussed. The intercalation of ClO₄^- into HOPG can be divided into three types depending on the number of graphite layers at the step site: When the layers of graphite are more than three, the intercalation becomes feasible; …

Electrochemical Properties Of Graphene/Porous Nano-Silicon Anode, Chun-Li Li, Guang Yang, Ping Zhang, Zhi-Yu Jiang

Journal of Electrochemistry

Porous nano-silicon (Si) was prepared by acid etching Al-Si alloy powder method, and used as an active material for fabricating a grapene/porous nano-Si electrode. The results of SEM and TEM measurements indicated that porous nano-Si powder was uniformly mixed with graphene by emulsification dispersion-ultrasonication method. As an anode for lithium ion battery, the graphene/porous nano-Si electrode presented relatively high performance in 1 mol•L^-1 LiPF6/EC:DMC = 1:1(by volume) + 1.5% (by mass) VC solution. At the charge and discharge current densities of 0.5A•g^-1, the first discharge capacity was 1768.6 mAh•g^-1 with coulombic efficiency of 68.3%. The discharge …

Three Dimensional Nanowire Array Piezo-Phototronic And Piezo-Photo-Magnetotronic Sensors, Satish C. Rai

University of New Orleans Theses and Dissertations

Piezotronic and piezo-phototronic is a burgeoning field of study which emerges from the coupling of intrinsic materials properties exhibited by non-centrosymmetric semiconductors. In the past decade research efforts were mainly focused on the wurtzite family of 1D nanostructures, with major emphasis on ZnO nanowire nanogenerators, MS piezotronic transistors, LEDs and photodetectors mainly integrated on single nanowires. In view of previously known advantages of charge carrier separation in radial heterojunctions, particularly in type-II core/shell nanowires, it can be anticipated that the performance of photosensing devices can be largely enhanced by piezo-phototronic effect. Moreover, the performance metrics can be further improved in …

Turning An Organic Semiconductor Into A Low-Resistance Material By Ion Implantation, Beatrice Fraboni, Alessandra Scidà, Piero Cosseddu, Yongqiang Wang, Michael Nastasi, Silvia Milita, Annalisa Bonfiglio

Nebraska Center for Energy Sciences Research: Publications

We report on the effects of low energy ion implantation on thin films of pentacene, carried out to investigate the efficacy of this process in the fabrication of organic electronic devices. Two different ions, Ne and N, have been implanted and compared, to assess the effects of different reactivity within the hydrocarbon matrix. Strong modification of the electrical conductivity, stable in time, is observed following ion implantation. This effect is significantly larger for N implants (up to six orders of magnitude), which are shown to introduce stable charged species within the hydrocarbon matrix, not only damage as is the case …

Shot Noise Thermometry For Thermal Characterization Of Templated Carbon Nanotubes, Robert A. Sayer, Sunkook Kim, Aaron D. Franklin, Saeed Mohammadi, Timothy Fisher

Robert A Sayer

A carbon nanotube (CNT) thermometer that operates on the principles of electrical shot noise is reported. Shot noise thermometry is a self-calibrating measurement technique that relates statistical fluctuations in dc current across a device to temperature. A structure consisting of vertical, top, and bottom-contacted single-walled carbon nanotubes in a porous anodic alumina template was fabricated and used to measure shot noise. Frequencies between 60 and 100 kHz were observed to preclude significant influence from 1/f noise, which does not contain thermally relevant information. Because isothermal models do not accurately reproduce the observed noise trends, a self-heating shot noise model has …

The Effect Of Frictional And Adhesion Forces Attributed To Slurry Particles On The Surface Quality Of Polished Copper, Yi-Koan Hong, Ja-Hyung Han, Tae-Gon Kim, Jin-Goo Park, Ahmed A. Busnaina

Ahmed A. Busnaina

The effect of frictional and adhesion forces attributed to slurry particles on the quality of copper surfaces was experimentally investigated during copper chemical mechanical planarization process. The highest frictional force of 9 Kgf and adhesion force of 5.83 nN were observed in a deionized water-based alumina slurry. On the other hand, the smallest frictional force of 4 Kgf and adhesion force of 0.38 nN were measured in an alumina slurry containing citric acid. However, frictional (6 Kgf) and adhesion (1 nN) forces of silica particles in the slurry were not significantly changed regardless of the addition of citric acid. These …

The Effect Of Frictional And Adhesion Forces Attributed To Slurry Particles On The Surface Quality Of Polished Copper, Yi-Koan Hong, Ja-Hyung Han, Tae-Gon Kim, Jin-Goo Park, Ahmed A. Busnaina

Ahmed A. Busnaina

The effect of frictional and adhesion forces attributed to slurry particles on the quality of copper surfaces was experimentally investigated during copper chemical mechanical planarization process. The highest frictional force of 9 Kgf and adhesion force of 5.83 nN were observed in a deionized water-based alumina slurry. On the other hand, the smallest frictional force of 4 Kgf and adhesion force of 0.38 nN were measured in an alumina slurry containing citric acid. However, frictional (6 Kgf) and adhesion (1 nN) forces of silica particles in the slurry were not significantly changed regardless of the addition of citric acid. These …

Doping Plasmon-Enhanced Tio2 With Zirconia To Improve Solar Energy Harvesting In Dye-Sensitized Solar Cells, Anastasia Pasche

Electronic Thesis and Dissertation Repository

Solar energy is a promising solution towards meeting the world’s ever-growing energy demand. Dye-sensitized solar cells (DSSCs) are hybrid organic-inorganic solar cells with potential for commercial application, but are plagued by inefficiency due to their poor sunlight absorption. Silver nanoparticles have been shown to enhance the absorptive properties of DSSCs, but their plasmonic resonance causes local hot spots, resulting in cell deterioration. This thesis studies the mitigation of thermal energy loss of plasmon-enhanced DSSCs by the co-incorporation of zirconia, a well-known thermostabilizer, into the cell’s photoactive material. TiO2 was also synthesized using green bio-sourced solvents in supercritical CO2 to compare …

Solution And Surface Properties Of Architecturally- And Compositionally-Complex Block Copolymers And Their Binary Mixtures, Jesse Lawrence Davis

Doctoral Dissertations

The spontaneous generation of complex structures from polymeric building blocks provides a simple yet effective route to create useful soft matter structures having potential application in a variety of nanotechnologies. The topology, chemical structure, block composition, and sequence of the constituent building blocks of polymers are tunable through synthetic chemistry. This tunability offers attractive opportunities to generate complex, yet well-defined structures with control over the geometry, packing symmetry, and microdomain structure. This thesis work involves the study of the self-assembly behaviors of architecturally complex amphiphilic block copolymers (ABCs). ABCs are composed of two or more chemically distinct blocks that are …

Failure Simulations At Multiple Length Scales In High Temperature Structural Alloys, Chao Pu

Doctoral Dissertations

A number of computational methodologies have been developed to investigate the deformation and damage mechanism of various structural materials at different length scale and under extreme loading conditions, and also to provide insights in the development of high-performance materials.

In microscopic material behavior and failure modes, polycrystalline metals of interest include heterogeneous deformation field due to crystalline anisotropy, inter/intra grain or phase and grain boundary interactions. Crystal plasticity model is utilized to simulate microstructure based polycrystalline materials, and micro-deformation information, such as lattice strain evolution, can be captured based on crystal plasticity finite element modeling (CPFEM) in ABAQUS. The comparison …

Ion Irradiation-Induced Microstructural Change In Sic, Chien-Hung Chen

Doctoral Dissertations

The high temperature radiation resistance of nuclear materials has become a key issue in developing future nuclear reactors. Because of its mechanical stability under high-energy neutron irradiation and high temperature, silicon carbide (SiC) has great potential as a structural material in advanced nuclear energy systems.

A newly developed nano-engineered (NE) 3C SiC with a nano-layered stacking fault (SFs) structure has been recently considered as a prospective choice due to enhanced point defect annihilation between layer-type structures, leading to outstanding radiation durability.

The objective of this project was to advance the understanding of gas bubble formation mechanisms under irradiation conditions in …

Epitaxial Growth Of Si-Ge-Sn Alloys For Optoelectronic Device Application, Aboozar Mosleh

Graduate Theses and Dissertations

Microelectronics industry has experienced a tremendous change over the last few decades and has shown that Moore’s law has been followed by doubling the number of transistors on the chip every 18 months. However, continuous scaling down of the transistors size is reaching the physical limits and data transfer through metal interconnects will not be able to catch up with the increasing data processing speed in the future. Therefore, optical data transfer between chips and on-chip has been widely investigated. Silicon based optoelectronics has received phenomenal attention since Si has been the core material on which microelectronic industry has been …

When 1 + 1 > 2: Nanostructured Composites For Hard Tissue Engineering Applications, Vuk Uskoković

Pharmacy Faculty Articles and Research

Multicomponent, synergistic and multifunctional nanostructures have taken over the spotlight in the realm of biomedical nanotechnologies. The most prospective materials for bone regeneration today are almost exclusively composites comprising two or more components that compensate for the shortcomings of each one of them alone. This is quite natural in view of the fact that all hard tissues in the human body, except perhaps the tooth enamel, are composite nanostructures. This review article highlights some of the most prospective breakthroughs made in this research direction, with the hard tissues in main focus being those comprising bone, tooth cementum, dentin and enamel. …

Incorporation Of High-K Hfo2 Thin Films In A-Igzo Thin Film Transistor Devices, Aaron Hamilton Bales

Masters Theses

In this study, HfO2 [hafnium oxide] thin films are investigated extensively as part of indium gallium zinc oxide (IGZO) thin film transistor (TFT) devices. They are incorporated into the TFTs, both as a gate insulator and a passivation layer. First, the HfO2 [hafnium oxide] films themselves are investigated through an annealing study and through I-V and C-V measurements. Then, HfO2 [hafnium oxide] is suggested as a replacement for commonly used SiO2 [silicon dioxide] gate insulator, as it has a dielectric constant that is 4 – 6 times higher. This higher dielectric constant allows for comparable TFT performance at a lower …

Imaging Thermal Conductivity With Nanoscale Resolution Using A Scanning Spin Probe, Abdelghani Laraoui, Halley Aycock-Rizzo, Yang Gao, Xi Lu, Elisa Riedo, Carlos A. Meriles

Department of Mechanical and Materials Engineering: Faculty Publications

The ability to probe nanoscale heat flow in a material is often limited by lack of spatial resolution. Here, we use a diamond-nanocrystal-hosted nitrogen-vacancy centre attached to the apex of a silicon thermal tip as a local temperature sensor. We apply an electrical current to heat up the tip and rely on the nitrogen vacancy to monitor the thermal changes the tip experiences as it is brought into contact with surfaces of varying thermal conductivity. By combining atomic force and confocal microscopy, we image phantom microstructures with nanoscale resolution, and attain excellent agreement between the thermal conductivity and topographic maps. …

Optical Communication Using Hybrid Micro Electro Mechanical Structures (Mems) And Commercial Corner Cube Retroreflector (Ccr), Sunny Kedia

USF Tampa Graduate Theses and Dissertations

This dissertation presents a free-space, long-range, passive optical communication system that uses electrostatically modulated microelectromechanical systems (MEMS) structures coupled with a glass total internal reflection (TIR)-type corner cube retroreflector (CCR) as a non-emitting data transmitter. A CCR consists of three mirrors orthogonal to each other, so that the incident beam is reflected back to the incident beam, source. The operational concept is to have a MEMS modulator fusion with TIR CCR, such that the modulators are working periodically to disrupt the evanescent waves at the air interface of one of the three back glass faces of a TIR CCR. The …

Direct Solutions To Perceptual Organization Problems, Ravi Kumar Panchumarthy

USF Tampa Graduate Theses and Dissertations

Quadratic optimization problems arise in various real world application domains including engineering design, microeconomics, genetic algorithms, integrated circuit chip design, probabilistic graphical models and computer vision. In particular, there are many problems in computer vision that require binary quadratic optimization such as motion segmentation, correspondences, figure-ground segmentation, clustering, grouping, subgraph matching, and digital matting. The objective of an optimization algorithm can be related to the state of a physical system, where the goal is to bring the initial arbitrary state of the system to a state with minimum possible energy. By recognizing that the Hamiltonian of nanomagnets can be expressed …

In Vacuo Fabrication And Electronic Structure Characterization Of Atomic Layer Deposition Thin Films, Michael Schaefer

USF Tampa Graduate Theses and Dissertations

Improvement of novel electronic devices is possible by tailor-designing the electronic structure at device interfaces. Common problems observed at interfaces are related to unwanted band alignment caused by the chemical diversity of interface partners, influencing device performance negatively. One way to address this problem is by introducing ultra-thin interfacial dipole layers, steering the band alignment in a desired direction. The requirements are strict in terms of thickness, conformity and low density of defects, making sophisticated deposition techniques necessary. Atomic layer deposition (ALD) with its Ångstrom-precise thickness control can fulfill those requirements.

The work presented here encompasses the implementation of an …

The Development Of A Novel Polymer Based System For Gene Delivery, Anh Van Le

FIU Electronic Theses and Dissertations

Gene therapy involves the use of nucleic acids, either DNA or RNA for the treatment, cure, or prevention of human diseases. Synthetic cationic polymers are promising as a tool for gene delivery because of their high level of design flexibility for biomaterial construction and are capable of binding and condensing DNA through electrostatic interactions.

Our lab has developed a novel polymer (poly (polyethylene glycol-dodecanoate) (PEGD), a polyester of polyethylene glycol (PEG) and dodecanedioic acid (DDA). PEGD is a linear viscous polymer that self-assembles into a vesicle upon immersion in an aqueous solution. A copolymer of dodecanedioc acid and polyethylene glycol …

Physically Equivalent Intelligent Systems For Reasoning Under Uncertainty At Nanoscale, Santosh Khasanvis

Doctoral Dissertations

Machines today lack the inherent ability to reason and make decisions, or operate in the presence of uncertainty. Machine-learning methods such as Bayesian Networks (BNs) are widely acknowledged for their ability to uncover relationships and generate causal models for complex interactions. However, their massive computational requirement, when implemented on conventional computers, hinders their usefulness in many critical problem areas e.g., genetic basis of diseases, macro finance, text classification, environment monitoring, etc. We propose a new non-von Neumann technology framework purposefully architected across all layers for solving these problems efficiently through physical equivalence, enabled by emerging nanotechnology. The architecture builds …

P-31 Characterization And Ph Dependence Stability Of Non-Organically Supported Silver Nanoparticles Produced Via Silver Oxide Reduction, Getahun Merga, Noah Chun

Celebration of Research and Creative Scholarship

The non-organically supported silver nanoparticles produced via the reduction of silver oxide by hydrogen and acetvlacetone (acac) have unusual stability in aqueous solution. We have previously reported that the negative potential, the hydrophilic surface that is created by the adsorbed hydroxide ions, which resembles an oxide interface, and the low ionic strength of the solution due to the small salt concentrations in this synthetic approach all contribute to the unusual stability of the colloidal suspension.[1] However, their stability with pH variation has not been well documented. In order to use these silver nanoparticles for biological relevance understanding of their suspension …

Label-Free Surface-Enhanced Raman Spectroscopy-Linked Immunosensor Assay (Slisa) For Environmental Surveillance, Vinay Bhardwaj

FIU Electronic Theses and Dissertations

The contamination of the environment, accidental or intentional, in particular with chemical toxins such as industrial chemicals and chemical warfare agents has increased public fear. There is a critical requirement for the continuous detection of toxins present at very low levels in the environment. Indeed, some ultra-sensitive analytical techniques already exist, for example chromatography and mass spectroscopy, which are approved by the US Environmental Protection Agency for the detection of toxins. However, these techniques are limited to the detection of known toxins. Cellular expression of genomic and proteomic biomarkers in response to toxins allows monitoring of known as well as …

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 …

Application Of 3d Printing Technology In Porous Anode Fabrication For Enhanced Power Output Of Microbial Fuel Cells, Bin Bian

Electronic Thesis and Dissertation Repository

Microbial fuel cells (MFCs) are widely researched for application in wastewater treatment. However, the current anodes used in MFCs often suffer from high fabrication cost and uncontrollable pore sizes. In this thesis, three-dimensional printing technique was utilized to fabricate anodes with different micro pore sizes for MFCs. Copper coating and carbonization were applied to the printed polymer anodes to increase the conductivity and specific surface area. Voltages of MFCs with various anodes were measured as well as other electrochemical tests such as linear sweep voltammetry and electrochemical impedance spectroscopy. 3D copper porous anode produced higher maximum voltages and power densities …

Molecular Helices As Electron Acceptors In High-Performance Bulk Heterojunction Solar Cells, Yu Zhong, M. Tuan Trinh, Rongsheng Chen, Geoffrey E. Purdum, Petr P. Khlyabich, Melda Sezen, Seokjoon Oh, Haiming Zhu, Brandon Fowler, Boyuan Zhang, Wei Wang, Chang-Yong Nam, Matthew Y. Sfeir, Charles T. Black, Michael L. Steigerwald, Yueh-Lin Loo, Fay Ng, X.-Y. Zhu, Colin Nuckolls

Publications and Research

Despite numerous organic semiconducting materials synthesized for organic photovoltaics in the past decade, fullerenes are widely used as electron acceptors in highly efficient bulk-heterojunction solar cells. None of the non-fullerene bulk heterojunction solar cells have achieved efficiencies as high as fullerene-based solar cells. Design principles for fullerene-free acceptors remain unclear in the field. Here we report examples of helical molecular semiconductors as electron acceptors that are on par with fullerene derivatives in efficient solar cells. We achieved an 8.3% power conversion efficiency in a solar cell, which is a record high for non-fullerene bulk heterojunctions. Femtosecond transient absorption spectroscopy revealed …

Nanomechanical And Nanotribological Characterization Of Sub-Micron Polymeric Spheres, Himanshu Kumar Verma

USF Tampa Graduate Theses and Dissertations

Friction between nanoscale objects has been a subject of great interest and intense research effort for the last two decades. However, the vast majority of the work done in this area has focused upon the sliding friction between two rigid, atomically smooth surfaces. Thus the parameter most explored has been the corrugation in the atomic potentials and how this affects the force required to slide one object across another. In truth, many nanoscale objects whose translation force is of practical interest are more spherical in nature. We hypothesize that the factors that determine the translation force will be related, not …

A Comparative Study Of Polyurethane Nanofibers With Different Patterns And Its Analogous Nanofibers Containing Mwcnts, Javier Macossay-Torres, Faheem A. Sheikh, Hassan Ahmad, Hern Kim, Gary L. Bowlin

Chemistry Faculty Publications and Presentations

Tissue engineering is a multidisciplinary field that has evolved in various dimensions in recent years. One of the main aspects in this field is the proper adjustment and final compatibility of implants at the target site of surgery. For this purpose, it is desired to have the materials fabricated at the nanometer scale, since these dimensions will ultimately accelerate the fixation of implants at the cellular level. In this study, electrospun polyurethane nanofibers and their analogous nanofibers containing MWCNTs are introduced for tissue engineering applications. Since MWCNTs agglomerate to form bundles, a high intensity sonication procedure was used to disperse …

Preparation And Characterization Of Carbon Supported Pd-Sb Composite Nanocatalysts For Formic Acid Electrooxidation, Long-Long Wang, Xiao-Lu Cao, Ya-Jun Wang, Jin-Hao Ping, Qiao-Xia Li

Journal of Electrochemistry

Palladium is considered as an efficient anode catalyst with high catalytic activity for electrooxidation of formic acid. To further improve the catalytic activity and stability, alloying or surface modification with Sb is an effective way. In this work, the well dispersed carbon supported Pd-Sb composite nanocatalysts (Pd-Sb/C) were synthesized by traditional impregnation reduction method with trisodium citrate as the complexing agent, sodium borohydride as the reducing agent. The morphologies of Pd-Sb/C and the effects of molar ratio of Pd to Sb on the electrocatalytic properties of Pd-Sb/C for HCOOH electrooxidation were studied. The XRD and XPS analyses on the as-prepared …

Effect Of Carbon Nanotubes On Anodic Properties Of Ti/Ru-Ir-Sn Oxides, Feng Lian, Yong-Lei Xin, Bo-Jiang Ma, Li-Kun Xu

Journal of Electrochemistry

The Ru-Ir-Sn metal oxide anodes coated on titanium (Ti/Ru-Ir-Sn) were prepared by thermal decomposition. The effects of amounts of carbon naotubes (CNTs) on anodic properties were studied by TGA, SEM, EDS, cyclic voltammetry, EIS, polarization measurements and accelerated life test. The thermogravimetric analysis and EDS spectrum data showed that the high temperature oxidation decomposition of CNTs did not take place under the condition of the sintering temperature of 470 ℃, and the CNTS still existed in the anode coating in an element form. Compared with the contrast samples, the surface crack of the coating increased, but remained typical morphology. Adding …