Chemistry Commons^™

A Promising Modification Of Pt Surfaces With Cnts For Decreasing Poisoning Impact In Direct Methanol Fuel Cells, Yaser M. Asal Mr., Islam M. Al-Akraa Dr, Aya A. Khalifa Ms.

Chemical Engineering

Direct methanol fuel cells (DMFCs) are clean energy sources that have many applications due to the high energy density of methanol as a fuel. However, this type of fuel cells (FCs) has limitations that are preventing it from being commercialized. One such limitation is the adsorption of intermediates such as CO into the surface of the Platinum (Pt) catalyst during methanol oxidation (MO) which deactivates its active sites, where the reaction is taking place, and leads to poisoning of the electrode over the long term. In this study, multi-walled carbon nanotubes (MWCNTs) have been introduced to the Pt-modified glassy carbon …

Recent Advances In Nanofluidic Electrochemistry For Biochemical Analysis, Zhong-Qiu Li, Zeng-Qiang Wu, Xing-Hua Xia

Journal of Electrochemistry

Nanofluidics, as a young research field, has been receiving more and more attentions. It has been successfully applied in various fields including nanoscale separation, biochemical sensing and energy conversion. The development of nanofluidics is closely related to electrochemistry that can provide a driving force for the study of the material transport characteristics in nanopores/nanochannels. On the other hand, nanopores/nanochannels can creat a microenvironment for study of spatially nanoconfined electrochemistry. The combination of nanofluidics and electrochemistry has given rise to many new theories and technologies for single molecule/particle analysis and nanofluid manipulation. Herein, we provide a review of the recent progresses …

Recent Progresses Of Enzymes Assembled In Nanochannels For Catalytic Reaction, Li Shangguan, Xuan Xu, Song-Qin Liu

Journal of Electrochemistry

The research of enzymes assembled and catalytic reaction not only is beneficial to exploit the essences of life’s activities, but also is significant in developing the practical application of enzymes in these areas including industrial production, analysis and detection, treatment of disease, etc. The effective immobilization and ordered assembly of enzymes are important methods for maintaining the catalytic activity, catalytic reaction stability and catalytic process controllability of enzymes. Among them, single or multi-enzymes are immobilized orderly in nanochannels that exhibit unique features and advantages, accordingly, the confinement effect of nanochannels can increase the selectivity and catalytic efficiency of enzymes through …

Electrocatalytic Nanomaterials For Reduction Of Hydrogen Peroxide As Potential Radioprotectors, Rui-Hong Jia, Jin-Xuan Zhang, Xiao-Dong Zhang, Mei-Xian Li

Journal of Electrochemistry

Nanomaterials have shown many potential application prospects in the biomedical field, such as medical imaging, drug delivery and biosensing due to their unique physical and chemical properties. In this review we focus on nanomaterials that have shown not only abilities of radiation protection, but also good electrocatalytic activities toward reduction reactions of hydrogen peroxide and oxygen. We discuss the abilities of radiation protection of these nanomaterials that are ascribed to their enzyme-like activities because their catalytic properties provide an effective pathway for scavenging free radicals in vivo via rapid reactions with reactive oxygen species. We also provide insights into electrocatalytic …

Correlated Optical Imaging And Electrochemical Recording For Studying Single Nanoparticle Collisions, Lin-Lin Sun, Wei Wang, Hong-Yuan Chen

Journal of Electrochemistry

With the development of nano-fabrications in recent years, a novel strategy based on random collisions of single electroactive nanoparticles (NPs) onto an inert ultramicroelectrode (UME) has been emerged in the field of nanoelectrochemistry, and named as single nanoparticles collisions (SNCs). The technique uses a chronoamperometric method to detect transient current generated by random collisions of single NPs onto an UME. By analyzing the current signal, one could study the properties of single NPs. Although this technique can detect electrochemical or electrocatalytic currents of a single NP, the traditional SNCs technology lacks necessary spatial resolution to identify and characterize a specific …

A Low Noise Temperature Control System For Nanopore-Based Single Molecule Analysis, Cheng-Yu Yang, Zhen Gu, Zheng-Li Hu, Yi-Lun Ying, Yi-Tao Long

Journal of Electrochemistry

Nanopore employs a single bio-molecule interface, which is a highly sensitive single-molecule detection technology for measuring single biomolecules such as DNA, RNA, protein, and peptide. The interaction between single molecule and nanopore is thermodynamically controlled. Therefore, it is urgent to precisely control the temperature of the nanopore system without introduction of any noise. In this paper, we have developed a low-noise temperature control system for single-molecule detection of nanopores to achieve precise regulation at the ambient temperature during measurements. The system utilizes the thermoelectric effect of the semiconductor refrigerating chip to heat or cool the detection chamber, while adopts electromagnetically …

Single Particle Impact Electrochemistry: Analyses Of Nanoparticles And Biomolecules, Jian-Hua Zhang, Yi-Ge Zhou

Journal of Electrochemistry

Single particle impact electrochemistry (SPIEC) has grown rapidly in recent years and shown great promise in the analysis of nanoparticle properties as well as the detection of biomolecules including DNA, RNA, protein, enzyme, bacteria, virus, vesicles and others. This minireview summarizes recent advances in electroanalytical applications of SPIEC according to different analytical methods, i.e., direct electrolysis of nanoparticles or labeled nanoparticles, direct electrolysis of soft particles encapsulated redox molecule, indirect electrochemistry of particles, area and diffusion blocking, and changes in current magnitude and collision frequency.

Non-Einstein Viscosity Phenomenon Of Acrylonitrile–Butadiene–Styrene Composites Containing Lignin–Polycaprolactone Particulates Highly Dispersed By High-Shear Stress, Sing-Hoon Kim, Kisuk Choi, Kyouk Ryeol Choi, Taesung Kim, Jonghwan Suhr, Kwang Jin Kim, Hyoung Jin Choi, Jae-Do Nam

Mechanical Engineering Faculty Research

Lignin powder was modified via ring-opening polymerization of caprolactone to form a lignin–polycaprolactone (LPCL) particulate. The LPCL particulates were mixed with an acrylonitrile–butadiene–styrene (ABS) matrix at an extremely high rotational speed of up to 3000 rpm, which was achieved by a closed-loop screw mixer and in-line melt extruder. Using this high-shear extruding mixer, the LPCL particulate size was controlled in the range of 3395 nm (conventional twin-screw extrusion) down to 638 nm (high-shear mixer of 3000 rpm) by altering the mixing speed and time. The resulting LPCL/ABS composites clearly showed non-Einstein viscosity phenomena, exhibiting reduced viscosity (2130 Pa·s) compared to …

Synthesis Of Metal Oxide Surfaces And Interfaces With Crystallographic Control Using Solid-Liquid-Vapor Etching And Vapor-Liquid-Solid Growth, Beth S. Guiton, Lei Yu

Chemistry Faculty Patents

The present invention provides integrated nanostructures comprising a single-crystalline matrix of a material A containing aligned, single-crystalline nanowires of a material B, with well-defined crystallographic interfaces are disclosed. The nanocomposite is fabricated by utilizing metal nanodroplets in two subsequent catalytic steps: solid-liquid-vapor etching, followed by vapor-liquid-solid growth. The first etching step produces pores, or “negative nanowires” within a single-crystalline matrix, which share a unique crystallographic direction, and are therefore aligned with respect to one another. Further, since they are contained within a single, crystalline, matrix, their size and spacing can be controlled by their interacting strain fields, and the array …

Implementation Of Multivariate Artificial Neural Networks Coupled With Genetic Algorithms For The Multi-Objective Property Prediction And Optimization Of Emulsion Polymers, David Chisholm

Master's Theses

Machine learning has been gaining popularity over the past few decades as computers have become more advanced. On a fundamental level, machine learning consists of the use of computerized statistical methods to analyze data and discover trends that may not have been obvious or otherwise observable previously. These trends can then be used to make predictions on new data and explore entirely new design spaces. Methods vary from simple linear regression to highly complex neural networks, but the end goal is similar. The application of these methods to material property prediction and new material discovery has been of high interest …

Nano Fab Lab 63, Brian K. Deemer, Josh Clemons, Nick Brodine, Delaney Fitzsimmons

Mechanical Engineering

Lawrence Livermore National Laboratories (LLNL) has several steps in the production process for ceramic nanofiber tubes that they would like to improve - electrospinning, cutting, rolling, sealing and heat treating. We undertook the challenge to deliver LLNL with a semi-automated process that efficiently integrates the steps of cutting, rolling, and sealing to save time and improve control over end dimensions. In this document, we discuss the technical background of the manufacturing steps currently followed to create nanofiber tubes, identify which steps are incorporated in our prototype and explain how they will interface with one another, define the design requirements, present …

Supercapacitors With Gate Electrodes, Tazima Selim Chowdhury

Dissertations

A new approach to improve the capacitance of supercapacitors (SC) is proposed in this study. A typical SC is composed of an anode and a cathode; a separator in between them assures an unintentional discharge of the capacitor. The study focuses on a family of structured separators, either electronically active or passive which are called gates. An active structured separator layer has been fabricated and analyzed. The structured separator has characteristics of electrical diode and is fabricated out of functionalized carbon nanotubes (CNT). Improvement of the overall capacitance of SC, equipped with either active or passive structured separators demonstrated a …

Speciation Of Gaseous Oxidized Mercury Molecules Relevant To Atmospheric And Combustion Environments, Francisco J. Guzman

Dissertations

Mercury is a pervasive and highly toxic environmental pollutant. Major anthropogenic sources of mercury emissions include artisanal gold mining, cement production, and combustion of coal. These sources release mostly gaseous elemental mercury (GEM), which upon entering the atmosphere can travel long distances before depositing to environmental waters and landforms. The deposition of GEM is relatively slow, but becomes greatly accelerated when GEM is converted to gaseous oxidized mercury (GOM) because the latter has significantly higher water solubility and lower volatility. Modeling GOM deposition requires the knowledge of its molecular identities, which are poorly known because ultra-trace (tens to hundreds part …

N8- Polynitrogen Stabilized On Carbon-Based Supports As Metal-Free Electrocatalyst For Oxygen Reduction Reaction In Fuel Cells, Zhenhua Yao

Dissertations

The sluggish oxygen reduction reaction (ORR) kinetics at the cathode is one of the key factors limiting the performance of polymer electrolyte membrane fuel cell (PEMFC). Platinum-based materials are the most widely studied catalysts for this ORR reaction while their large-scale practical application in fuel cells is hindered due to their scarcity and low stability. Therefore, highly active, low cost and robust non-Pt catalysts are being developed to overcome the drawbacks. Recently, a novel polynitrogen N8- (PN) stabilized on multiwall carbon nanotube (MWNT) was synthesized under ambient condition for the first time by our group and demonstrated high ORR activities. …

Surface-Enhanced Raman Detection Of Glucose On Several Novel Substrates For Biosensing Applications, Laila Saad Alqarni

Dissertations

The small normal Raman cross-section of glucose is considered to be a major challenge for its detection by Surface Enhanced Raman Spectroscopy (SERS) for medical applications. These applications include blood glucose level monitoring of diabetic patients and evaluation of patients with other medical conditions, since glucose is a marker for many human diseases. This dissertation focuses on Surface-Enhanced Raman Scattering primarily for the detection of glucose. Some experiments also are carried out for the detection of the corresponding enzyme glucose oxidase that is used in electrochemical glucose sensors and in biofuel cells. This project explores the possibility of utilizing Surface …

Triperyleno[3,3,3]Propellane Triimides: Achieving A New Generation Of Quasi-D3h Symmetric Nanostructures In Organic Electronics, Lingling Lv, Josiah Roberts, Chengyi Xiao, Zhenmei Jia, Wei Jiang, Chad Risko, Lei Zhang

Chemistry Faculty Publications

Rigid three-dimensional (3D) polycyclic aromatic hydrocarbons (PAHs), in particular 3D nanographenes, have garnered interest due to their potential use in semiconductor applications and as models to study through-bond and through-space electronic interactions. Herein we report the development of a novel 3D-symmetric rylene imide building block, triperyleno[3,3,3]propellane triimides (6), that possesses three perylene monoimide subunits fused on a propellane. This building block shows several promising characteristics, including high solubility, large π-surfaces, electron-accepting capabilities, and a variety of reactive sites. Further, the building block is compatible with different reactions to readily yield quasi-D_3h symmetric nanostructures (9, …

An In-Situ Study Of The Aqueous Speciation Of Uranium (Vi) Under Hydrothermal Conditions, Diwash Dhakal

Graduate Theses/Dissertations

Rigorous study of the speciation distribution of uranyl-chloride bearing solutions under hydrothermal conditions is important to understand the transport mechanism of uranium underground, which is of uttermost interest to parties studying the geological uranium deposits and those studying the possibilities of geological repositories for spent nuclear waste. I report an in-situ Raman spectroscopic study of the speciation distribution of aqueous uranyl-chloride complexes upto 500°C conducted using a HDAC as the high PT spectroscopic cell. The samples studied contained the species UO₂²⁺, UO₂Cl⁺, UO₂Cl₂⁰ and UO₂Cl₃^{- …}

Defect Chemistry And Ion Intercalation During The Growth And Solid-State Transformation Of Metal Halide Nanocrystals, Bo Yin

McKelvey School of Engineering Graduate Student Theses & Dissertations

Abstract of the Dissertation

Defect Chemistry and Ion Intercalation During the Growth and Solid-State Transformation of Metal Halide Nanocrystals

Semiconductor metal halides as light-sensitive materials have applications in multiple areas, such as photographic film, antibacterial agents and photocatalysts. One focus of this dissertation is to achieve novel morphologies of ternary silver bromoiodide (AgBr1-xIx, 0

For the silver halide system, we demonstrate that the anion composition of AgBr1-xIx nanocrystals determines their shape through the introduction of twin defects as the nanocrystals are made more iodide-rich. AgBr1-xIx nanocrystals grow as single-phase, solid solutions with the rock salt crystal structure for anions compositions …

Application Of X-Ray Grating Interferometry To Polymer/Flame Retardant Blends In Additive Manufacturing, Omoefe Joy Kio

LSU Doctoral Dissertations

X-ray grating interferometry is a nondestructive tool for visualizing the internal structures of samples. Image contrast can be generated from the absorption of X-rays, the change in phase of the beam and small-angle X-ray scattering (dark-field). The attenuation and differential phase data obtained complement each other to give the internal composition of a material and large-scale structural information. The dark-field signal reveals sub-pixel structural detail usually invisible to the attenuation and phase probe, with the potential to highlight size distribution detail in a fashion faster than conventional small-angle scattering techniques. This work applies X-ray grating interferometry to the study of …

“Polysoaps” Via Raft Copolymerization To Form Well-Defined Micelles For Water Remediation And Targeted Drug Delivery Applications, Phillip Pickett

Dissertations

Amphiphilic copolymers have become increasingly important for environmental and biological applications due to their behavioral characteristics in aqueous solution. For example, structurally-tailored statistical amphiphilic copolymers or “polysoaps” can self-assemble into micelles or other architectures in water at various concentrations. Polysoaps may be differentiated from small molecule surfactant micelles in their capability to self-assemble into unimolecular associates (unimolecular micelles) with no dependence on concentration. Such micelles offer enormous potential for dispersion of hydrophobic species in water at high dilution. Importantly, each polymer chain forms its own micelle and upon dilution, these micelles remain intact and capable of dispersing hydrocarbon material in …

Engineering Multifunctional And Morphologically Diverse Polymer Brush Surfaces, Cassandra M. Reese

Dissertations

The combination of surface-initiated polymerization (SIP) and post-polymerization (PPM) serves as a powerful approach to fabricate complex, multifunctional polymer films, which can be precisely tuned for desired surface engineering applications. Careful manipulation of PPM parameters such as reaction conditions, the tethered brush parameters, and the physical properties of the unbound post-modifier greatly influence the depth of penetration of the post-modifier and the polymer brush compositional heterogeneity. This dissertation focuses on engineering polymer brush surfaces with multifunctional chemistries and tunable morphologies by investigating the PPM parameters that dictate the distribution of post-modifiers on grafted polymer brush surfaces.

The first chapter of …

Using Green Emitting Ph-Responsive Nanogels To Report Environmental Changes Within Hydrogels: A Nanoprobe For Versatile Sensing, Mingning Zhu, Dongdong Lu, Shanglin Wu, Qing Lian, Wenkai Wang, L. Andrew Lyon, Weiguang Wang, Paulo Bártolo, Brian R. Saunders

Engineering Faculty Articles and Research

Remotely reporting the local environment within hydrogels using inexpensive laboratory techniques has excellent potential to improve our understanding of the nanometer-scale changes that cause macroscopic swelling or deswelling. Whilst photoluminescence (PL) spectroscopy is a popular method for such studies this approach commonly requires bespoke and time-consuming synthesis to attach fluorophores which may leave toxic residues. A promising and more versatile alternative is to use a pre-formed nanogel probe that contains a donor/acceptor pair and then “dope” that into the gel during gel assembly. Here, we introduce green-emitting methacrylic acid-based nanogel probe particles and use them to report the local environment …

Surface Immobilization Of Terpyridine Compounds, Elizabeth Hallett

Chemical Engineering Undergraduate Honors Theses

The deoxydehydration (DODH) of polyols to alkenes is a promising method of producing high-value chemical feedstocks from biomass-derived materials. Current catalytic systems for DODH require the use of costly reducing agents that generate stoichiometric amounts of chemical waste. Immobilizing catalysts on electrode surfaces using chemical linking groups eliminates the need for sacrificial reductants. In this work, glassy carbon electrodes were modified with 4’-(3,4-dihydroxyphenyl)-2,2’:6’,2’’-terpyridine to investigate o-benzoquinone as a potential linking group for DODH, and possibly for other reactions. Previous studies involving electrodes modified with quinone-containing compounds have primarily been focused on catalyzing the oxidation of NADH; the nature or …

In Situ Nmr Parameter Monitoring Systems And Methods For Measuring Ph And Temperature, Ming Huang, Lingyu Chi, Rex E. Gerald Ii, Jie Huang, Annalise R. Pfaff, Klaus Woelk

Electrical and Computer Engineering Faculty Research & Creative Works

Devices and methods are provided for measuring temperatures and pHs of a sample in situ using NMR spectroscopy, and for sealing one or more ends of a capillary tube after a reference material has been added to the capillary tube, which is used in an in situ NMR temperature measurement device. A method for measuring a pH of a sample in situ using NMR spectroscopy includes providing an in situ NMR pH measurement device. This device includes a sample housing member configured to house a target sample, at least one pH sensor configured to exhibit an NMR spectral change due …

Synthesis And Characterization Of Dielectric And Multiferroic Nanocrystalline Transition Metal Oxide Materials And Nanocomposites, Frederick A. Pearsall

Dissertations, Theses, and Capstone Projects

Nanocrystalline transition metal oxides with unique chemical, physical, magnetic and dielectric properties have very broad applications, ranging from photocatalysis, capacitor energy storage and 4-state memory. Frequency stable, high permittivity nanocomposite capacitors produced under mild processing conditions offer an attractive replacement to MLCCs derived from conventional ceramic firing. In one project reported herein, 0-3 nanocomposites were prepared using BaTiO₃ (barium titanate, BTO) nanocrystals, suspended in a poly(furfuryl alcohol) matrix, resulting in a stable, high effective permittivity, low and stable loss dielectric. Effective medium approximations were used to compare this with similar nanocomposite systems. The use of synthesized BTO nanocrystal photocatalysts …

Experimental And Computational Study On Magnetic Nanowires Of Layered Titanates, Caleb Layne Heath

Graduate Theses and Dissertations

The intricate nanostructures of layered titanates are unique among nanomaterials due to their easy and inexpensive syntheses. These nanomaterials have been proven valuable for use in industries as varied as energy, water treatment, and healthcare, and can be produced at industrial scales using already existent equipment. They have complex morphology, and surface structure well suited to chemical modification and doping. However, there is a longstanding debate on their lattice structure after the doping. There is a long-unmet need to understand, using both experimental and simulation methods, how dopants alter the clay-like layered crystal structure and associated physical and chemical properties. …

Surface-Enhanced Infrared Absorption Spectroscopy- Surface Sensitive In Situ Label-Free Spectroelectrochemistry, Lie Wu, Jian-Long Sun, Xiu-E Jiang

Journal of Electrochemistry

Surface-enhanced infrared absorption spectroscopy (SEIRAS), especially in attenuated total reflectance (ATR) mode, taking advantages of surface-enhancement and near-field optical effect of enhancing substrate, is a ultra-sensitive infrared spectroscopy, which could achieve surface-selected detection at a sub-monolayer level. Since the enhancing substrate could simultaneously serve as a working electrode, ATR-SEIRAS is a readily surface-sensitive in situ label-free spectroelectrochemistry technique. With the advantages of small influence from metal species on enhancement effect, good potential reversibility of spectra, simple surface selection rule and sensitivity to polar molecules, ATR-SEIRAS has been widely applied in the fields of orientation analysis and species identification of interfacial …

High-Efficiency Nitrite Sensor Based On Cop Nanowire Array, Fu-Ling Zhou, Xiao-Li Xiong, Xu-Ping Sun

Journal of Electrochemistry

Nitrite has a negative impact on the environment and human health. The long-term consumption of nitrite-containing foods has a carcinogenic risk. Therefore, the analysis and detection of nitrite are important. It is of great significance to develop high-efficiency electrocatalysts to achieve high sensitivity and selectivity for nitrite detection. The cobalt phosphide nano-array (CoP/TM) was obtained by hydrothermal and low-temperature phosphating. The electrochemical test results show that the constructed CoP/TM was a highly efficient electrochemical reduction nitrite catalyst with the excellent sensing performance and response time less than 3 s, as well as the linear detection range of 1.0 μmol·L^{-1 …}

Preparation And Capacitive Property Of Two-Dimensional Multilayer Ti3C2TX-Mxene/Ppy-Nw Composite Material, Lu Chen, Xuan Jian, Min He, Mi-Mi Zhang, Xiao-Die Chen, Lou-Jun Gao, Zhen-Hai Liang

Journal of Electrochemistry

In this paper, the two-dimensional multilayered Ti₃C₂T_x-MXene was obtained by hydrofluoric acid etching method on the bulk phase material MAX(Ti₃AlC₂) substrate. The two-dimensional multilayered Ti₃C₂T_x-MXene/PPy-NW composite electrode materials were successfully prepared by combining the one-dimensional polypyrrole nanowires (PPy-NW) with two-dimensional multilayered Ti₃C₂T_x-MXene. The morphologies and compositions of the synthetic materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Electrochemical tests showed that Ti₃C_{2 …}

In Situ/Operando Visualization Of Electrode Processes In Lithium-Sulfur Batteries: A Review, Shuang-Yan Lang, Xin-Cheng Hu, Rui Wen, Li-Jun Wan

Journal of Electrochemistry

Lithium-sulfur (Li-S) batteries have been regarded as one of the most promising candidates for the next-generation energy storage devices. Fundamental understanding of the structure and evolution processes at electrode-electrolyte interfaces is essential to the further development. In this review, we summarize recent advances in the interfacial observations by means of various in situ/operando visualization techniques, including scanning probe microscopy (SPM), electron microscopy (EM), X-ray microscopy (XRM) and optical microscopy (OM). The real-time investigation provides important evidence for the morphology and component changes including S/Li₂S transformation, polysulfide dissolution on cathodes and Li/solid electrolyte interphase (SEI) evolution on anodes, which …