Nanoscience and Nanotechnology Commons^™

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 …

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; …

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 …

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 …

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 …

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 …

Effect Of Adsorption Potential On Co Oxidation At Au@Pt Nanoparticles Electrodes, A Surface Enhanced Raman Spectroscopic Study, Pu Zhang, Yi Wei, Yong-Li Zheng, Yan-Xia Chen, Zhong-Qun Tian

Journal of Electrochemistry

The adsorption/oxidation of CO on the 55 nm Au@0.7 nm Pt nanoparticles electrode in both potentiodynamic and potentiostatic modes were investigated by surface enhanced Raman spectroscopy in a thin layer electrochemical flow cell under controlled mass transport, with the aim of clarifying the origin CO oxidation at lower electrode potentials (in current pre-wave region of corresponding cyclic voltammograms). Our results demonstrated that the CO oxidation kinetics differed significantly from the three kinds of different CO adsorption history, with almost no CO oxidation current in the pre-peak potential region after 0.35 V_RHE CO adsorption with or without subsequent holding the …

Broadband Sum-Frequency Generation Spectroscopic Invstigations Of Thiocyanate On Polycrystalline Au Electrode In Alkaline Solutions, Mei Xu, Jing-Jing Wang, Zhi-Chao Huangfu, Ng Ying Wa, Yu-Han He, Zhao-Hui Wang

Journal of Electrochemistry

Broadband sum frequency generation (BB-SFG) spectroscopy has been used to investigating the potential-dependent adsorption behaviors of thiocyanate ions on polycrystalline Au electrode in alkaline solutions. During the positive scan, a change in the Stark slope (dω_C-N/dE) for C—N stretching mode can be observed in the range of -1.1 V ~ 0.2 V (vs. SCE), which implies that the orientation of adsorbed thiocyanate ions at Au electrode surface changes from N-bound (dω_C-N/dE=45 cm^-1·V^-1) form to S-bound (dω_C-N/dE = 16.2 cm^-1·V^{-1 …}

Tunable Photonic Multilayers From Stimulus-Responsive, Photo-Crosslinkable Polymers, Maria C. Chiappelli

Doctoral Dissertations

This dissertation describes the synthesis of photo-crosslinkable copolymers and their utilization for the fabrication and testing of tunable and responsive one-dimensional (1D) photonic multilayers. Photonic multilayers exhibit structural color due to the interference of incident light at layer interfaces, providing a convenient route towards optically responsive materials that do not rely on potentially light- or oxygen-sensitive chromophore-containing pigments and dyes. A fabrication technique based on sequential spin-coating and crosslinking of photo-crosslinkable polymers is used to assemble tunable and responsive photonic multilayers. Chapter One introduces the fundamental underlying principles of 1D photonic structures and explores their importance in a variety of …

Field Scale Application Of Nanoscale Zero Valent Iron: Mobility, Contaminant Degradation, And Impact On Microbial Communities, Chris M.D. Kocur

Electronic Thesis and Dissertation Repository

This thesis began by verifying that nanoscale zero valent iron (nZVI) synthesis methods could be scaled up and implemented at the field scale in a safe manner. This led to successful demonstration of nZVI injection and mobility under constant head gravity injection into a contaminated utility corridor in Sarnia, Ontario. Where field studies have fallen short in the past was linking the somewhat qualitative field geochemical parameters to other evidence of nZVI transport. Definitive nZVI detection was elusive in previous field studies due to the highly reactive nature of the particles caused by their high surface area. nZVI was detected …

Nanoscaled Cellulose And Its Carbonaceous Material: Application And Local Structure Investigation, Yujie Meng

Doctoral Dissertations

In this dissertation, cellulose nanocrystals three-dimensional morphology, size distribution, and the crystal structure were statistically and quantitatively investigated. Lognormal distribution was identified as the most likely for cellulose nanocrystals’ size distribution. Height and width dimensions were shown to decrease toward the ends from the midpoint of individual CNCs, implying a spindle-like shape. XRD analysis of crystallite size accompanied with TEM and AFM measurements revealed that the cross-sectional dimensions of individual switchgrass CNC were either rectangular or elliptical shape, with an approximately 3~5 nm [nanometer] lateral element length range. A sponge-like carbon aerogel from microfibril cellulose with high porosity, ultra-low density, …

Effect Of Surface Omniphobicity On Drying By Forced Convection, Madani A. Khan, Jeffrey Alston, Andrew Guenthner

STAR Program Research Presentations

Low energy surfaces can strongly repel both oil and water. Recently these surfaces have been fabricated on various substrates including fabric, aluminum, stainless steel and many other materials. In this experiment we explore the use of low energy surface deposition on aluminum alloy, stainless steel and silicon substrates, to enhance the drying rate of liquids removed from the surface by forced convection. We control surface roughness by substrate abrasion and by the growth of Al₂O₃ nanograss to enhance liquid repellence by use of a hierarchical texture. Liquid repellence of the substrates is measured by contact angles of …

Wet Chemical Synthesis And Characterization Of Nanomaterials For Solar Cell Applications, Krystle N. Sy, Ramprasad Gandhiraman, Jessica E. Koehne

STAR Program Research Presentations

During long term space missions, it is necessary to have a reliable source of energy. Solar cells are an easy and reliable way to convert energy from the sun to electrical energy. NASA has used solar cells manufactured on Earth as an energy source for many of its missions. In order to develop technologies that will enable high efficiency solar cells, we are synthesizing nanostructured materials. A range of nanostructured materials, such as titanium dioxide nanowires, nickel nanoparticles, copper nanoparticles, and silver nanoparticles/nanowires, are synthesized. In this work, we are reporting on the synthesis of these nanomaterials and the electron …

Three-Dimensional Scaffolds Of Graphene, Carbon Nanotubes And Transition-Metal Oxides For Applications In Electronics, Sensors And Energy Storage, Gilbert N. Mbah

Department of Chemistry: Dissertations, Theses, and Student Research

Electronics, sensors and energy storage devices are the new waves behind economic development, security and communication¹. Engineering small sizes of electronic, sensors and energy storage devices is the hurdle limiting efficient, portable and vast applications of Nano-devices for economic, security and communication advancement². Silicon the major material used in transistors has approached its limit to fabricated Nano-devices³. The discovery of free standing, one atomic layer thick and two-dimensional graphene sheets with high conductivity, inert, high specific surface area, stable and high tensile strength material in 2004 has shown capabilities to replaced silicon in electronics, …

Local Heating With Lithographically Fabricated Plasmonic Titanium Nitride Nanoparticles, Urcan Guler, Justus Ndukaife, Gururaj Naik, Agbai Nnanna, Alexander Kildishev, V. Shalaev, Alexandra Boltasseva

U. Guler

Titanium nitride is considered a promising alternative plasmonic material and is known to exhibit localized surface plasmon resonances within the near-infrared biological transparency window. Here, local heating efficiencies of disk-shaped nanoparticles made of titanium nitride and gold are compared in the visible and near-infrared regions numerically and experimentally with samples fabricated using e-beam lithography. Results show that plasmonic titanium nitride nanodisks are efficient local heat sources and outperform gold nanodisks in the biological transparency window, dispensing the need for complex particle geometries.

Synthesis Of Palladium And Palladium-Copper Nanostructures As Electrocatalysts, Haibin Wu

Graduate Theses and Dissertations

Pd and its alloys are alternatives of Pt as promising catalysts and electrocatalysts for many reactions. Size controlled synthesis of nanoparticles remains a major research subject, since smaller size particles show better catalytic performance. In this work, we developed a modified chemical wet method to prepare Pd and Pd-Cu nanostructures with uniform small size. Different sizes and shapes of Pd nanostructures were successfully synthesized by using the two reducing agents (i.e., L-ascorbyl-6-palmitate or phenylphosphinic acid). The reducing agents play a role to control the final morphologies and sizes of particles. The use of L-ascorbyl-6-palmitate favors to form irregular branch shapes …

Surface Modification Of Noble Metal Nanostructures Toward Biomedical Applications, Samir V. Jenkins

Graduate Theses and Dissertations

Noble metal nanostructures have seen a steady increase in biomedical application over the last several decades; new diagnostic and therapeutic modalities are under intense investigation. Many of these applications are possible because of post-synthetic modifications to the particle surface. These modifications take a variety of forms and can significantly affect the pharmacokinetics of these particles. In this work, various surface modifications were investigated. Particle agglomeration, which occurs when particle surfaces remain in contact, can significantly affect the toxicity and efficacy of a nanomedicine. Darkfield microscopy and single-particle ICP-MS were developed as complementary methods to detect agglomeration in blood, with the …

Energy Harvesting-Aware Design For Wireless Nanonetworks, Shahram Mohrehkesh

Computer Science Theses & Dissertations

Nanotechnology advancement promises to enable a new era of computing and communication devices by shifting micro scale chip design to nano scale chip design. Nanonetworks are envisioned as artifacts of nanotechnology in the domain of networking and communication. These networks will consist of nodes of nanometer to micrometer in size, with a communication range up to 1 meter. These nodes could be used in various biomedical, industrial, and environmental monitoring applications, where a nanoscale level of sensing, monitoring, control and communication is required. The special characteristics of nanonetworks require the revisiting of network design. More specifically, nanoscale limitations, new paradigms …

Engineering The Ground State Of Complex Oxides, Derek Joseph Meyers

Graduate Theses and Dissertations

Transition metal oxides featuring strong electron-electron interactions have been at the forefront of condensed matter physics research in the past few decades due to the myriad of novel and exciting phases derived from their competing interactions. Beyond their numerous intriguing properties displayed in the bulk they have also shown to be quite susceptible to externally applied perturbation in various forms. The dominant theme of this work is the exploration of three emerging methods for engineering the ground states of these materials to access both their applicability and their deficiencies.

The first of the three methods involves a relatively new set …

Studies Of Periodic And Quasiperiodic Gold Nanohole Arrays And Their Applications, Zhaoliang Yang

Electronic Thesis and Dissertation Repository

Wavelength to refractive index sensitivity and resonance wavelength position are two very important performance characteristics for nanohole array based surface plasmon resonance sensors while these characteristics are mostly researched on periodic nanohole arrays, instead of quasiperiodic nanohole arrays. This thesis deduces theoretical equations about the wavelength to refractive index sensitivity and resonance wavelength position of quasiperiodic nanohole arrays. Theoretical analysis shows that wavelength to refractive index sensitivity is not associated with geometry pattern, hole size or pitch but with the wavelength. A novel surface plasmon resonance platform is built by transferring gold films patterned with quasiperiodic nanohole arrays to the …

Inertial Force-Driven Synthesis Of Near-Infrared Plasmonic Nanosphere Composites: Physicochemical Characterizations, Joseph Noel Batta-Mpouma

Graduate Theses and Dissertations

Near-infrared (NIR) responsive nanoparticles (NPs) like gold nanorods (GNRs) are important in biomedical fields because of their transparency for biological tissues. Although GNRs are sought after as contrast agents for theranostics in cancer studies, capping ligands like cetyltrimethylammonium bromide (CTAB) for the GNR synthesis are toxic for biological tissues. The need for an alternative to toxic GNRs is of interest to alleviate the problem.

This work aimed to optimize the synthesis of NIR responsive nanosphere composites (NSCs) by inertial force (g-force) using colloidal gold NPs as model, elucidate the mechanism for the NSC formation, and study their detailed physicochemical characteristics. …

Tio 2 Fibers: Tunable Polymorphic Phase Transformation And Electrochemical Properties, Edna Garcia, Qiang Li, Xing Sun, Karen Lozano, Yuanbing Mao

Chemistry Faculty Publications and Presentations

A series of one-dimensional (1D) nanoparticle-assembled TiO2 fibers with tunable polymorphs were prepared via a novel and large scale ForceSpinning® process of titanium tetraisopropoxide (TTIP)/polyvinylpyrrolidone (PVP) precursor fibers followed with a thermal treatment at various calcinations temperatures. The thermal and structural transformations were characterized by thermogravimetric analysis/differential scanning calorimetry, scanning electron microscopy, and X-ray diffraction. The influence of polymorphic phase of the TiO2 fibers on the electrochemical performance in neutral aqueous 1 M Na2SO4 electrolyte was investigated. The polymorphic amorphous/anatase/rutile TiO2 fibers prepared at 450 °C achieved a highest capacitance of 21.2 F g−1 (6.61 mF cm−2) at a current …