Materials Chemistry Commons^™

Ii-Vi Semiconductor Nanowire Array Sensors Based On Piezotronic, Piezo-Phototronic And Piezo-Photo-Magnetotronic Effects, Shuke Yan

University of New Orleans Theses and Dissertations

With the rapid progress of nanotechnologies, there are two developing trends for the next generation of sensors: miniaturization and multi-functionality. Device miniaturization requires less power consumption, or even self-powered system. Multi-functional devices are usually based on multi-property coupling effects. Piezoelectric semiconductors have been considered to be potential candidates for self-powered/multi-functional devices due to their piezotronic coupling effect. In this dissertation, ZnO and CdSe nanowire arrays have been synthesized as the piezoelectric semiconductor materials to develop the following self-powered/multi-functional sensors: (1) self-powered gas sensors of ZnO/SnO₂, ZnO/In₂O₃, ZnO/WO₃ and CdSe nanowire arrays have been …

Nanocomposites Of Polypyrrole And Cobalt Oxide As Efficient And Stable Multifunctional Materials For Supercapacitors And Overall Water Splitting, Ahlam Alghamdi

Electronic Theses & Dissertations

NANOCOMPOSITES OF POLYPYRROLE AND COBALT OXIDE AS EFFICIENT AND STABLE MULTIFUNCTIONAL MATERIALS FOR SUPERCAPACITORS AND OVERALL WATER SPLITTING

An Abstract of the Thesis by

Ahlam Alghamdi

The main objective of this study is to synthesize nanostructured cobalt oxide decorated on polypyrrole using a facile method for energy applications. For this, polypyrrole was first synthesized using a chemical polymerization method. In the second step, a varying amount of cobalt oxide was decorated on polypyrrole using a hydrothermal process. The synthesized materials were structurally and electrochemically characterized. It was observed that the electrochemical properties of the composites depend on their composition. The …

Evaluation Of The Biocompatibility And Micromechanical Properties Of Experimental Dental Adhesives, Hoda Moussa

Forensic Science Theses

The purpose of this study was to investigate the biocompatibility and micromechanical properties of newly synthesized antibacterial monomer and cross-linker functional surfactants into a commercially available dental adhesive (Single Bond, 3M ESPE, Saint Paul, MN, USA) at three concentrations (0.05, 0.1, 0.25 mg/mg). All groups were analyzed by evaluation of micro-tensile bond strength, ultimate tensile strength, cell viability, antibacterial properties, and surface micro-hardness. Scanning electron microscopy (SEM) was used for interfacial characterization.

Human extracted molars were used as a substrate for bonding adhesives for the micro-tensile bond strength (MTBS) and scanning electron microscopy (SEM) studies. Twenty resin-dentin beams (0.9 ± …

Polymer Nanocomposites Containing High Aspect Ratio Particulates: Innovation In Co-Extruded Multilayer Barrier Films, Kevin Meyers

Dissertations

Delaminated montmorillonite (MMT) clay/ maleic anhydride grafted LLDPE nanocomposite multilayer films with alternating layers of LDPE were produced through multilayer co-extrusion. The MMT concentration within the nanocomposite layers was increased through annealing the films in the melt due to a mismatch in interdiffusion rates of the polymer layers. Analysis of the nanocomposite layers upon annealing revealed that the platelets impinged upon one another resulting in significant improvement in oxygen barrier in the multilayer system, exceeding the results of bulk nanocomposites.

Model analysis demonstrated that increasing the nanoplatelet aspect ratio or initial concentration in the filled layers would lead to even …

Photoelectrochemical Studies On Non-Noble Metal Based Catalysts Towards Tandem Solar Water Splitting, Arun Siddarth Sridhar

Dissertations

Photoelectrochemical (PEC) water splitting makes direct use of solar energy incident on semiconductor photoelectrodes, and it is a convenient, economic option to produce high purity hydrogen at low temperatures. The use of multiple light absorbers can increase overall solar energy utilization and provide a solution to the trade-off between overall band gap and band edge positioning of photoelectrodes specific to solar water oxidation and water reduction. The study of non-noble metal based catalysts for hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) are essential for economic practical commercialization of photo-electrolyzers. This dissertation focuses on the use of a variety …

Understanding The Coating-Substrate Interface Changes And Degradation Caused By Environmental Acclimation With Water And Electrolytes, Russell Vick

Honors Theses

While it is well known that polymeric coatings are used to protect metals from corrosion, efficient and reliable protocols for quantifying and estimating protective coatings’ lifetimes have yet to match real-time results in rate or in detected mechanisms of material failure. Alkoxysilane pretreatments are widely utilized for substrate preparation and improved coating system performance by changing the metal substrate surface morphology to improve adhesion at the coating-substrate interface by creating a foundation and excluding water from the system. Three pretreatments used were 3-aminopropyltriethoxy silane (APS), tetraethylortho silicate (TEOS), N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAS). They were investigated to improve the understanding of the relationships …

Highly Flame Retardant And Bio-Based Rigid Polyurethane Foams Derived From Orange Peel Oil, Chunyang Zhang

Electronic Theses & Dissertations

Polyurethane is an important class of polymer which is being used for various industrial applications in the form of rigid foams, flexible foams, thermoplastic, elastomer, coating, and adhesive. Especially there is a huge market for rigid polyurethane foams for their applications as thermal insulating material in building and housing. In general, polyurethanes are prepared using polyols and diisocyanates. Most of the polyols used by industries are petrochemical based. In this project, a novel polyol from an orange peel oil-based derivative, limonene dimercaptan, was synthesized using one step photochemical thiol-ene reaction. The synthesized polyol was used to prepare flame retardant polyurethane …

Long-Range Electrostatic Interactions In Gold Catalysis And Fluorinating Reagent Development., Zhichao Lu

Electronic Theses and Dissertations

Our research focus is on applying two long range electrostatic interactions--coulombic interaction between ion pairs and hydrogen bonding—to two tasks: exploring counterion effects in gold catalysis and utilizing hydrogen bonding for fluorinating reagent development. Cationic gold catalysis is considered one of the most important breakthroughs in organic synthesis over the past two decades. A wealth of empirical information on counterion effects is now available regarding homogeneous gold catalysis. However, the rational understanding of the counterion effect on reactivity is still elusive. We proposed a widely applicable model to rationalize the kinetic effect in gold catalyzed reaction. We first solved the …

Surface Reaction And Diffusion Kinetics In Semiconducting Metal Oxide Film Gas Sensors, Aravind Reghu

Electronic Theses and Dissertations

Chemiresistive metal oxide gas sensors based on materials such as SnO₂, ZnO, and TiO₂, have been investigated extensively by many researchers for a wide range of applications. The band bending model, based on the surface chemistry of highly reactive ionosorbed species (O₂^- or O^-) and the semiconducting material properties of SnO₂, TiO₂ and ZnO, adequately predicts the dependence of the change in sensor conductivity (Δσ) as a function of target gas pressure and temperature. However, the band bending model is not applicable to gas sensors based on reducible oxides …

Lithium And The Foreseeable Future, Paolo Vargas

Mechanical Engineering Undergraduate Honors Theses

This paper aims to clarify the uncertainties regarding worldwide lithium resource availability in the years to come. Previous studies made on the subject are presented with some ambiguity and this work intends to fill the gaps. The information and data presented throughout this script with respect to global lithium resources and reserves are mostly based on data released by the United States Geological Survey (USGS). Lithium resource availability in the future is a point of paramount significance primarily for the automotive, portable electronics, and the power generation industry. Since, a change of supply would ultimately affect the price of lithium, …

Synthesis Of A Silsesquioxane Based Supramolecular Polymer, Rachel Bianculli

Honors Projects

Research toward smart materials, specifically self-healing polymers, is an expanding topic within the materials science field. These materials rely heavily on dynamic crosslinking that is achieved by inducing different degrees of hydrogen bonding, van der Waals forces, etc. This work, demonstrated by research previously done within the Ostrowski research group, shows how coordination bonds of transition metals have been shown to create light activated, self-healing properties. Work done with these light-activated chromium (III) complexes with a poly(butylyene-co-ethylene) backbone have shown how metal—ligand coordination geometries can tune mechanical properties of the polymeric material. However, these materials suffer from being incredibly soft …

Preparation Of Ni(Dpim)2Cl2 Complex For The Electrocatalytic Reduction Of Co2, Li-Pu Zhang, Dong-Fang Niu, Xin-Sheng Zhang

Journal of Electrochemistry

A new Ni(dpim)₂Cl₂complex using 2-(diphenylphosphino)-1-methylimidazole (dpim) as ligand was prepared and served as a catalyst for the electrochemical reduction of CO₂. The electrochemical redox behavior of Ni(dpim)₂Cl₂ in CH₃CN/TPABF₄ solution under nitrogen atmosphere showed the two-electron irreversible reduction at -0.7 V and one-electron quasi-reversible reduction at -1.3 V. After bubbling CO₂ into the electrolyte, the reduction peak appeared at -1.3 V became irreversible and the peak current increased from 0.48 mA·cm^-2 to 0.55 mA·cm^-2. Moreover, the peak current at -1.3 V could further increase …

Interaction Between Energy And Electrocatalysis—A Review On The 1st Young Scientist Forum On Energy Electrocatalysis, Hong Li, Wen-Bin Cai

Journal of Electrochemistry

No abstract provided.

Electrochemical Oxidation Of P-Chlorophenol On Porous Ti/Bdd Electrode Cooperated With Cathode Dechlorination, Rong-Ling Chen, Wei-Min Huang, Ya-Peng He, Jun Shi, Hai-Bo Lin

Journal of Electrochemistry

The electrochemical oxidation of p-chlorophenol on porous Ti/BDD electrode cooperated with synergistic effect of cathode dechlorination was studied. Electrochemical degradation tests of p-chlorophenol were conducted in single and double compartment electrolytic cells separately, and the results showed that the mineralization happened mainly in the anode region. The product of chloride ions produced from the cathodic reduction of 4-chlorophenol in the single cell migrated to the anode region and further generated active chlorine toward electro-catalytic oxidation. At the same time, the chloride ion produced from the cathode of the double cell was difficult to be migrated to the anode …

Preparation Of Co3O4/Ti Electrocatalytic Membrane Electrode For Catalytic Oxidation Of Benzyl Alcohol, Yu-Mei Zheng, Zhen Yin, Hong Wang, Jian-Xin Li

Journal of Electrochemistry

The cobalt oxide(Co₃O₄) nanoparticles were loaded on microporous Ti membrane to prepare Co₃O₄/Ti electrocatalytic membrane electrode by dip-coating method. The microstructures and electrochemical properties of Co₃O₄/Ti electrocatalytic membrane were investigated. The Co₃O₄/Ti electrocatalytic membrane reactor (ECMR) assembled by using the Co₃O₄/Ti electrocatalytic membrane as an anode was adopted for catalytic oxidation of benzyl alcohol to produce benzaldehyde and benzoic acid.The effects of different operation parameters on benzyl alcohol conversion, and selectivity to benzaldehyde and benzoic acid of ECMR were studied. …

A Label-Free Immunosensor Based On K3[Fe(Cn)6] And Aldehyde-Functionalized Pyridinium, Xia Hu, You-Ming Shen, Guang-Yu Shen

Journal of Electrochemistry

A novel aldehyde-functionalized pyridinium was successfully synthesized. Using K₃[Fe(CN)₆] as a redox species modified on the surface of the electrode through Poly(diallyldimethylammonium chloride), we developed a label-free immunosensor based on aldehyde-functionalized pyridinium that was applied to simplify antibody immobilization on the electrode surface, in which no additional chemical cross-linking was required. In addition, the introduction of K₃[Fe(CN)₆] on the surface of electrode avoided the use of other redox species in the electrolyte solution. Under the optimal experimental conditions, differential pulse voltammetry (DPV) signals corresponding to different α-Fetoprotein (AFP) concentrations were measured. …

Effects Of Rotating Magnetic Fields On Pem Fuel Cell Performance, Mao-Liang Wu, En-Ze Wang, Guang-De Pan, Zhong-Jun Liu, Fei Xie

Journal of Electrochemistry

Proton Exchange Membrane (PEM) fuel cell performance may be improved by application of additional magnetic fields. In this work, one square permanent magnet, made of either 16 combination cylinder magnets with homopolarity or 16 combination cylinder magnets with heteropolarity, was exerted on the fuel cell surface to produce additional magnetic field affecting PEM fuel cell performance. The influences of magnetic field status (rotating, static and none) on polarization and power density curves measured in a PEM fuel cell were investigated. The results verified the benefit of magnetic field, proving that the magnetic field distribution could improve the fuel cell output. …

Preparation And Properties Of Manganese Oxide And Polyaniline-Carbon Composite Electrode, Tian-Tian Zhou, Bing Wu, Chao Deng, Ying Gao

Journal of Electrochemistry

The polyaniline-carbon (PAnC) electrode was prepared by the polymerization of aniline monomer and activated carbon in ice water bath, and followed by chemical deposition of manganese dioxide MnO₂-PAnC composite material. The specific capacitance of MnO₂-PAnC reached 459 F•g^-1. The cyclic voltammetric results showed a small deformation in the voltammogram curve obtained with the MnO₂-PAnC electrode at high scan rate, indicating good reversibility and capacitive properties. The AC impedance results revealed that the MnO₂-PAnC electrode displayed the smallest charge transfer resistance and the fastest diffusion
rate of surface ions than other …

Electrochemical Performance Of Moo2-C Composite Coatings, Quan-Yi Li, Qi Yang, Yan-Hong Zhao

Journal of Electrochemistry

The molybdenum dioxide-carbon(MoO₂-C)composite coatings on the surface of Cu foils were prepared by simple knife coating route and followed by sintering in vacuum. The morphology, composition, structure and electrochemical performance of the MoO₂-C composite coatings were investigated. The results demonstrated that the MoO₂-C composite coatings consist of MoO₂ nano-particles with monoclinic crystal structure and amorphous carbon. Some MoO₂ nano-particles with a size range of 5-30nm were loaded on the surface of carbon matrices; while some MoO₂ nano-particles with a size of ~5nm were encapsulated inside. The composite coatings showed porous structure …

Preparations And Corrosion Protection Investigations Of Diethylene Triamine Penta(Methylene Phosphonic Acid)-Zn2+ Conversion Coatings On Cold Rolled Steel Substrates, Wei He, Ru Yan, Ying-Qi Wang, Xiang Gao, Hou-Yi Ma

Journal of Electrochemistry

Novel diethylene triamine penta(methylene phosphonic acid) (DTPMPA)-zinc ion (Zn²⁺) conversion coatings with uniform blue color and excellent corrosion protection were directly formed on the cold rolled steel (CRS) substrates by immersing a CRS plate into the film-forming solutions containing the appropriate concentrations of DTPMPA and Zn²⁺ ion at the proper pH. In this paper, surface morphologies and elemental compositions of DTPMPA-Zn²⁺ conversion coatings were characterized by SEM and EDS, respectivey. The surface functional groups, chemical constituents and binding modes to the substrates were investigated by means of FTIR and XPS methods. The influences of DTPMPA concentrations …