Nanoscience and Nanotechnology Commons^™

Boosting Electrocatalytic Activity Of Nitrogen-Doped Graphene/Carbon Nanotube Composite For Oxygen Reduction Reaction, Yu Zhang, Jin-Song Hu, Wen-Jie Jiang, Lin Guo, Zi-Dong Wei, Li-Jun Wan

Journal of Electrochemistry

Developing low-cost catalysts with high electrocatalytic activity for oxygen reduction reaction (ORR) has recently attracted much attention because the sluggish ORR currently limits the performance and commercialization of fuel cells and metal-air batteries as well. Nitrogen doped carbon materials have been considered as a promising candidate for the replacement of high-cost and scarce Pt-based catalysts although their electrocatalytic activity still needs to be much improved. In this work, an improved nitrogen-doped graphene/carbon nanotubes composite (N-rGO/CNT) was developed as an efficient ORR electrocatalyst. It was found that the ORR activity of N-rGO/CNT composite could be significantly enhanced by introducing iron in …

Fabrication Of Pattern Of Graphene Oxide And Au Nanoparticles By Microcontanct Printing Technique, Wen-Hui Pang, Xiao-Jian Xiao, Meng-Wei Ye, Kai-Chao Deng, Jing Tang

Journal of Electrochemistry

Graphene oxide (GO) was prepared by modified Hummers method. Using the GO solution as "ink", Au nanoparticles (AuNPs) and GO were transferred to the surface of ITO substrate modified with (3-aminopropyl) triethoxysilane (APTES/ITO) in a sequence. The transferred AuNPs and GO could form a uniform and dense composite pattern which was characterized by FE-SEM and AFM. Moreover, using the APTES/ITO substrate surface potential as zero, the sequences of the surface potential were APTES>GO>Au.

Dynamic Control Of Plasmonic Resonances With Graphene Based Nanostructures, Naresh Kumar Emani

Open Access Dissertations

Light incident on a metallic structure excites collective oscillations of electrons termed as plasmons. These plasmons are useful in control and manipulation of information in nanoscale dimensions and at high operating frequencies. Hence, the field of plasmonics opens up the possibility of developing nanoscale optoelectronic circuitry for computing and sensing applications. One of the challenges in this effort is the lack of tunable plasmonic resonance. Currently, the resonant wavelength of plasmonic structure is fixed by the material and structural parameters. Post-fabrication dynamic control of a plasmonic resonance is rather limited.^ In this thesis we explore the combination of optoelectrical properties …

Structural Characterization Of Multimetallic Nanoparticles, Vineetha Mukundan

Open Access Dissertations

Bimetallic and trimetallic alloy nanoparticles have enhanced catalytic activities due to their unique structural properties. Using in situ time-resolved synchrotron based x-ray diffraction, we investigated the structural properties of nanoscale catalysts undergoing various heat treatments. Thermal treatment brings about changes in particle size, morphology, dispersion of metals on support, alloying, surface electronic properties, etc. First, the mechanisms of coalescence and grain growth in PtNiCo nanoparticles supported on planar silica on silicon were examined in detail in the temperature range 400-900°C. The sintering process in PtNiCo nanoparticles was found to be accompanied by lattice contraction and L1₀chemical ordering. …

Advanced Iii-V / Si Nano-Scale Transistors And Contacts: Modeling And Analysis, Seung Hyun Park

Open Access Dissertations

The exponential miniaturization of Si CMOS technology has been a key to the electronics revolution. However, the continuous downscaling of the gate length becomes the biggest challenge to maintain higher speed, lower power, and better electrostatic integrity for each following generation. Hence, novel devices and better channel materials than Si are considered to improve the metal-oxide-semiconductor field-effect transistors (MOSFETs) device performance. III-V compound semiconductors and multi-gate structures are being considered as promising candidates in the next CMOS technology. III-V and Si nano-scale transistors in different architectures are investigated (1) to compare the performance between InGaAs of III-V compound semiconductors and …

Optical Spectroscopy And Langmuir Probe Diagnostics Of Microwave Plasma In Synthesis Of Graphene-Based Nanomaterials, Alfredo D. Tuesta

Open Access Dissertations

Along with the revolutionary discovery and development of carbon nanostructures, such as carbon nanotubes and graphitic sheets, has arrived the potential for their application in the fields of medicine, bioscience and engineering due to their exceptional structural, thermal and electrical properties. As roll-to-roll plasma deposition systems begin to provide means for large scale production of these nanodevices, a detailed understanding of the environment responsible for their synthesis is imperative in order to more accurately design and control the growth of carbon nanodevices. To date, the understanding of the chemistry and kinetics that govern the synthesis of carbon nanodevices is only …

Transport And Optical Properties Of Low-Dimensional Complex Systems, Andrii Iurov

Dissertations, Theses, and Capstone Projects

Over the last five years of my research work, I, my research was mainly concerned with certain crucial tunneling, transport and optical properties of novel low-dimensional graphitic and carbon-based materials as well as topological insulators. Both single-electron and many-body problems were addressed. We investigated the Dirac electrons transmission through a potential barrier in the presence of circularly polarized light. An anomalous photon-assisted enhanced transmission is predicted and explained in a comparison with the well-known Klein paradox. It is demonstrated that the perfect transmission for nearly-head-on collision in an infinite graphene is suppressed in gapped dressed states of electrons, which is …

Control Of Light-Matter Interaction Via Dispersion Engineering, Harish Natarajan Swaha Krishnamoorthy

Dissertations, Theses, and Capstone Projects

This thesis describes the design, fabrication and characterization of certain nanostructures to engineer light-matter interaction. These materials have peculiar dispersion properties owing to their structural design, which is exploited to control spontaneous emission properties of emitters such as quantum dots and dye molecules. We will discuss two classes of materials based on the size of their unit cell compared to the wavelength of the electromagnetic radiation they interact with. The first class are hyperbolic metamaterials (HMM) composed of alternate layers of a metal and a dielectric of thicknesses much smaller than the wave- length. Using a HMM composed of silver …

Electrochemical And Surface Enhanced Raman Spectroscopic Studies Of Benzimidazole On Nickel Electrode, Ping-Jie Wei, Ya-Xian Yuan, Min-Min Xu, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

By measuring cyclic voltammograms and polarization curves, the inhibition effects of benzimidazole (BMIH) concentration in acetonitrile system on a nickel electrode were investigated. It was found that the oxidation and the corrosion potentials shifted positively, and the oxidation current decreased with the increase in the concentration of BIMH. Potential dependent adsorption and film formation behavior of BMIH on the nickel electrode were investigated by in situ SERS spectroscopy. With the potential moving from negative direction to positive direction, the complexes made of BIMH and nickel were formed, preventing the nickel electrode from corrosion. In addition, the 0.001 mol·L^-1 of …

Synthesis Of Silver Nanoparticles Supported On Graphene Quantum Dots For Oxygen Reduction Reaction, Jian Ju, Wei Chen

Journal of Electrochemistry

Silver-based catalysts have been extensively investigated as the platinum substituted catalysts due to their high catalytic efficiency, low cost and long-term durability. In this study, the surfactant-free silver nanoparticles supported on graphene quantum dots were synthesized through a facile approach without addition of any other protecting ligands and reducing agents. The “surface-clean” silver nanoparticles had remarkable electrocatalytic performance towards oxygen reduction reaction (ORR) with the most efficient four-electron transfer process. Compared with commercial Pt/C catalyst, the hybrid nanoparticles showed comparable catalytic performance for ORR but much higher tolerance to methanol. Such silver nanoparticles supported on graphene quantum dots may have …

Room Temperature Ionic Liquid Templated Meso-Macroporous Material By Self-Assembled Giant Gold Nanoparticles And Its Enhancement On The Direct Electrochemistry Of Cytochrome C, Pei Li, Dong-Ping Zhan, Yuan-Hua Shao

Journal of Electrochemistry

Room temperature ionic liquid (RTIL) is used as a soft-template to organize a meso-macroporous material constructed by self-assembled giant gold nanoparticles which are capped by L-cysteine. First, L-cysteine capped gold nanoparticles can self-assembly to form nanowires and sub-micrometer spherical giant particles due to the static interaction and/or the condensation reaction between the carboxyl and amino groups at the outer terminal of the ligand. Second, the spherical assembled particles can form a quasi-solid gel when grinding with a hydrophobic RTIL, 1-octyl-3-metyllimidazolium hexafluorophosphate. Finally, when the composite gel is coated on a glassy carbon electrode and then polarized by using cyclic voltammetry …

In-Situ Afm Force Curve Investigations On Layered Structures Of Au(111)-Ionic Liquid Interfaces And Temperature Dependence, Xiao Zhang, Yun-Xin Zhong, Jia-Wei Yan, Bing-Wei Mao

Journal of Electrochemistry

By utilizing in-situ AFM force curve measurements systematic investigations have been carried out on Au(111)-ionic liquid interface in BMIPF₆ and OMIPF₆ of imidazolium-based ionic liquids with different lengths of alkyl side chains. The temperature dependence of the number, thickness and stability of the layered structures of each system are studied by performing AFM force curve measurements at potentials far negative of the PZC. The layered structures at Au (111)/BMIPF₆ interface are composed of two charged interior layers and two neutral exterior layers at -1.0 V, while those at Au (111)/OMIPF₆ interface only one charged interior layer …

A Sensitive And Label-Free Electrochemical Aptasensor Based On Signal Amplification Of Carbon Nanotubes, Chun-Yan Deng, Hui-Min Fan, Juan Xiang, Yuan-Jian Li

Journal of Electrochemistry

A label-free electrochemical sensing electrode for highly sensitive detection of adenosine was constructed based on the signal amplification of carbon nanotubes (CNTs). The change in the interfacial feature of the modified electrode was characterized by electrochemical impedance spectroscopy. Using [Ru(NH₃)₆]³⁺ as the signaling moiety, adenosine with concentrations as low as 0.027 nmol·L^-1 can be selectively detected. Additionally, the fabrication of this present aptasensor was simple, time-saving and cost-effective. Compared with other reported aptasensors, the proposed aptasensor had advantages of excellent sensitivity, selectivity and simplicity, which plays a potential role in development of aptasensor.

Investigation Of The Dynamics Of Photocarriers During Photoelectrochemical Water Splitting By Combination Of Photoelectrochemistry And Transient Absorption Spectroscopy, Wen-Hua Leng

Journal of Electrochemistry

Semiconductor photoelectrochemical hydrogen production is an important and promising technology for utilizing solar energy. The efficiency of hydrogen production depends on the efficiencies of separation and transport of photo-generated carriers. A deep understanding of the behavior of these processes has guiding significance for designing efficient solar hydrogen device. photoelectrochemical and transient absorption spectroscopy methods are powerful tool for studying the microscopic dynamics and mechanism of photocatalytic reaction. This review describes the part of the latest results of the author regarding the semiconductor photoelectrochemical hydrogen production obtained by these methods,and the problems and future research priorities in this field are proposed.

Preparation And Lithium Storage Performance Of Sn-Snsb Nanoparticles, Yao Xiao, Jiao-Hong Wu, Qi Wang, Ling Huang, Jun-Tao Li, Shi-Gang Sun

Journal of Electrochemistry

Tin was widely studied as alternative anode material to carbon for lithium-ion batteries thanks to its much higher theoretical capacity. However, a pure tin electrode suffers severely from its poor cycleability due to mechanical fatigue caused by volume change during lithium insertion and extraction processes. Tin-based alloy may improve the cycleability property of tin electrode. In this article, we report facile synthesis of spherical Sn-SnSb nanopartciles using a simple solvent-thermal approach. It is amazing to find that the spherical Sn-SnSb nanoparticles can circumvent volume changes effectively during charge-discharge process. Electrochemical discharge/charge results show that the spherical Sn-SnSb nanoparticles electrode exhibits …

Electrochemical Fabrication Of Two-Dimensional Flower-Like Pt Nanostructures For Methanol Electrocatalytic Oxidation, Xia Wang, Jun Hu, Yong-Jun Li

Journal of Electrochemistry

Two-dimensional flower-like Pt nanostructures (2D FPNs) were fabricated on glassy carbon substrates by galvanostatical electrochemical technique. The electrolyte was the HAuCl₄ + HClO₄ aqueous solution without addition of any structure-directing organic reagent, which made as-prepared Pt nanostructures cleaner, exhibiting much higher reactivity. Scanning electron microscopic images revealed that 2D FPNs were spherical Pt nano-flowers constructed by the smallest building blocks, nano-leaves. The number density of spherical Pt nano-flowers can be tuned by controlling the electrodeposition time. High resolution transmission electron microscopic images indicated that each nano-leaf was formed by growing along Pt(111) direction. Electrocatalytic activities of as-prepared 2D …

Optical Resonators And Fiber Tapers As Transducers For Detection Of Nanoparticles And Bio-Molecules, Huzeyfe Yilmaz

McKelvey School of Engineering Graduate Student Theses & Dissertations

In recent years, detection of biological interactions on single molecule level has aspired many researchers to investigate several optical, chemical, electrical and mechanical sensing tools. Among these tools, toroidal optical resonators lead the way in detection of the smallest particle/molecule with the real time measurements. In this work, bio-sensing capabilities of toroidal optical resonators are investigated. Bio-sensing is realized via measuring the analyte-antigen interaction while the antigen is immobilized through a novel functionalization method.

Not long ago, detection of single nanoparticles using optical resonators has been accomplished however the need for cost-effective and practical transducers demands simpler tools. A tapered …

Granular Matter: Microstructural Evolution And Mechanical Response, Aashish Ghimire, Ishan Srivastava, Timothy S. Fisher

The Summer Undergraduate Research Fellowship (SURF) Symposium

Heterogeneous (nano) composites, manufactured by the densification of variously sized grains, represent an important and ubiquitous class of technologically relevant materials. Typical grain sizes in such materials range from macroscopic to a few nanometers. The morphology exhibited by such disordered materials is complex and intricately connected with its thermal and electrical transport properties. It is important to quantify the geometric features of these materials and simulate the fabrication process. Additionally, granular materials exhibit complex structural and mechanical properties that crucially govern their reliability during industrial use. In this work, we simulate the densification of soft deformable grains from a low-density …

Bayesian Calibration Tool, Sveinn Palsson, Martin Hunt, Alejandro Strachan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Fitting a model to data is common practice in many fields of science. The models may contain unknown parameters and often, the goal is to obtain good estimates of them. A variety of methods have been developed for this purpose. They often differ in complexity, efficiency and accuracy and some may have very limited applications. Bayesian inference methods have recently become popular for the purpose of calibrating model's parameters. The way they treat unknown quantities is completely different from any classical methods. Even though the unknown quantity is a constant, it is treated as a random variable and the desired …

Self-Assembly Of Gold Nanosphere Dimers By Inertial Force, George Andrew Christopher Sakhel

Graduate Theses and Dissertations

The morphology and composition of a nanoparticle (NP) play a critical role in determining the NP's properties and function. To date, researchers have created a myriad of NPs of different shapes, sizes, and compositions with interesting attributes and applications ushering a revolution in medicine, electronics, microscopy, and microfluidics.

In this study, gold (Au) nanosphere dimers (NSDs) have been synthesized through a novel self-assembly method. These particles were created from Au NPs mono-dispersed in aqueous solution via a process of centrifugation and capping agent replacement. Au NSDs consist of two Au NPs combined together with minimal gaps between them. Optical spectral …

Nanoscale Manipulation Of Pristine And Functionalized Freestanding Graphene Using Scanning Tunneling Microscopy, Matthew Ackerman

Graduate Theses and Dissertations

Over the past ten years the 2D material graphene has attracted an enourmous amount of attention from researchers from across diciplines and all over the world. Many of its outstanding electronic properties are present only when it is not interacting with a substrate but is instead freestanding. In this work I demonstrate that pristine and functionalized freestanding graphene can be imaged using a scanning tunneling microscope (STM) and that imaging a flexible 2D surface is fundamentally different from imaging a bulk material due to the attraction between the STM tip and the sample. This attraction can be used to manipulate …

A Biophysical Understanding Of The Applications And Implications Of Nanomaterials, Nicholas Geitner

All Dissertations

The last few decades have seen an explosion in the study and application of nanomaterials that continues to grow at a dizzying pace. Despite exciting applications in nano-enabled electronics, materials, medicine, and environmental remediation, an understanding of the interactions of these materials with natural materials and systems and the resulting implications lags severely behind. The purpose of this Dissertation is to illuminate these interactions as well as develop novel environmental applications from a biophysical perspective. Following an introduction and literature review in Chapter 1, Chapters 2-4 will explore the application of dendritic polymers as novel and biocompatible oil dispersants for …

Characterizing Nanoparticle Size By Dynamic Light Scattering Technique (Dls), Marzia Zaman

Graduate Theses and Dissertations

The Dynamic Light Scattering Technique was used to determine the size, shape and diffusion coefficient of nanoparticle. The intensity auto correlation functions of light scattered by particles in a solution were measured by using a photomultiplier tube and analyzed to get the relaxation rates for decay of intensity correlations, which correspond to the diffusion constants pertaining to the motion of the particle. In the case of nanorods there are two types of motion - translational and rotational. By dis-entangling the relaxation rates, corresponding to these two types of motion, the shape and size of nanoparticle could be characterized. These experiments, …

Nickel Aluminum Shape Memory Alloys Via Molecular Dynamics, Keith Ryan Morrison

Open Access Theses

Shape memory materials are an important class of active materials with a wide range of applications in the aerospace, biomedical, and automobile industries. These materials exhibit the two unique properties of shape memory and superelasticity. Shape memory is the ability to recover its original shape by applying heat after undergoing large deformations. Superelasticity is the ability to undergo large, reversible deformations (up to 10%) that revert back when the load is removed. These special properties originate from a reversible, diffusionless solid-solid phase transformation that occurs between a high temperature austenite phase and a low temperature martensite phase. The development of …

Synthesis And Characterization Of Crystalline Iron Nanoparticles From Zerovalent Iron Sandwich Complexes, Anh Tue Nguyen

Open Access Theses

In this project we present a systematic study on the synthesis of crystalline iron nanocubes by thermal decomposition of an iron sandwich complex, ( π-C₅H₅)Fe⁰(π-C ₆H₇), in the presence of oleylamine and oleylamine.HCl as surfactants and n-decane as a solvent. The presence of oleylamine.HCl is essential for the reproducible formation of crystalline iron cores.^ Reaction parameters such as temperature, surfactant concentration, effect of counterion, and organoiron reagent structure were investigated in order to obtain iron nanoparticles with uniform size and shape. The nanoparticles, which were characterized by …

Biodegradable Electrospun Nanofibers Coated With Platelet-Rich Plasma For Cell Adhesion And Proliferation, Luis Diaz-Gomez, Carmen Alvarez-Lorenzo, Angel Concheiro, Maite Silva, Fernando Dominguez, Faheem A. Sheikh, Travis Cantu, Raj Desai, Vanessa L. Garcia, Javier Macossay-Torres

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Biodegradable electrospun poly(ε-caprolactone) (PCL) scaffolds were coated with platelet-rich plasma (PRP) to improve cell adhesion and proliferation. PRP was obtained from human buffy coat, and tested on human adipose-derived mesenchymal stem cells (MSC) to confirm cell proliferation and cytocompatibility. Then, PRP was adsorbed on the PCL scaffolds via lyophilization, which resulted in uniform sponge-like coating of 2.85 (s.d. 0.14) mg/mg. The scaffolds were evaluated regarding mechanical properties (Young’s modulus, tensile stress and tensile strain), sustained release of total protein and growth factors (PDGF-BB, TGF-β1 and VEGF), and hemocompatibility. MSC seeded on the PRP-PCL nanofibers showed an increased adhesion and proliferation …

Surface Enhanced Raman Spectroscopic Studies Of Pyridine Adsorbed On Ti/Au@Sio2 Film Electrode, Min-Min Xu, Ke Liu, Qing-Hua Guo, Jian-Lin Yao

Journal of Electrochemistry

This study was performed based on shell-isolated nanoparticles-enhanced Raman spectroscopy (SHINERS) technology. The Au@SiO₂ nanoparticles were prepared and characterized by TEM and cyclic voltammetry. It was shown that the shell of SiO₂ was compact. The high quality signal measured by surface enhanced Raman spectroscopy (SERS) was obtained from the adsorbed pyridine on Ti/Au@SiO₂ electrode. The origin of the SERS signals was further confirmed by testing Pt and Ni electrodes. In addition, potential dependent adsorption behavior was investigated. It was found that pyridine was adsorbed parallel on the surface from -0.1 V to -0.6 V, and converted to …

Horseradish Peroxidase-Attapulgite Clay Nanocomposites: Fabrication And Application To Sensing The Extracellular H2O2 Released From Cells, Ping Wu, Chen-Xin Cai

Journal of Electrochemistry

The nanostructured attapulgite clay was employed as a support matrix for immobilizing horseradish peroxidase (HRP). FTIR and electrochemical methods demonstrated that HRP had been effectively assembled on attapulgite surface with the formation of HRP-attapulgite nanocomposites. The HRP-attapulgite hybrid was deposited on the glassy carbon (GC) electrode forming the HRP-attapulgite/GC electrode. Cyclic voltammetric results showed a pair of well-defined redox peaks, which were ascribed to direct electron transfer (DET) of HRP, with the formal potential E₀′ = -335 mV (vs. SCE) in the phosphate buffer solution (PBS, pH 7.0). The dependence of E₀′ on solution pH indicated …

Novel Electrochemical Interfaces Based On Functional Nanomaterials And Their Related Applications, Cheng-Zhou Zhu, Lei Han, Shao-Jun Dong

Journal of Electrochemistry

Due to the unique optical, electronic, magnetic and catalytic properties, functional nanomaterials provide new opportunities for the rapid development in a variety of disciplines and show considerable promise in different fields. Specifically, constructions of the novel electrochemical interface using various nanomaterials and exploring their advanced electrochemical properties have received great attention to develop electrochemical devices with potential applications. In this account, we focus on our up-to-date progress in the construction of novel electrochemical interfaces based on nanomaterials, mainly highlighting our research advances on electrochemical sensors, fuel cells and fluorescence spectroelectrochemistry. These novel advanced nanomaterials endow them excellent performances and open …

Preparation And Photocatalytic Properties Of Zno Nanorod Arrays On Ti Substrates, Jia-Ming Yang, Ling-Jun Han, Li-Ping Zhong, Zhen-Hai Liang

Journal of Electrochemistry

In this paper, the uniform ZnO nanorod arrays were prepared by galvanostatic electrodeposition on Ti Substrates. The morphology and structure of samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of the concentration of Zn(NO₃)₂ and the deposition current on the morphology of the ZnO nanorod arrays were investigated. Photocatalytic properties of ZnO nanorod arrays were investigated by degradation of methyl orange (MO) under UV-light irradiation. The analysis revealed that the concentration of Zn(NO₃)₂ and the deposition current strongly influenced the morphology of the ZnO nanorod arrays. Compared with …