Chemistry Commons^™

Syntheses Of Ag@Pd@Pt Nanoparticles With Tunable Shell Thickness For Electrochemical Oxidation Of Formic Acid, Xiao-Dong Lin, Du-Hong Chen, Zhong-Qun Tian

Journal of Electrochemistry

In an effort to lower cost of a catalyst, the silver (Ag) core with palladium (Pd) layer then platinum (Pt) island (Ag@Pd@Pt) nanoparticles were synthesized and the electrocatalytic activity of Ag@Pd@Pt nanoparticles on formic acid was compared with that of Au@Pd@Pt nanoparticles reported previously. The results showed that the existence of a small amount of Pt could significantly improve the activity of the catalyst. When the surface coverage of Pt approached 0.5 monolayers, the activity of Ag@Pd@Pt nanoparticles reached the maximum. Though the onset potential of the electro-oxidation was slightly more positive (about 50 mV), the overall electrocatalytic activity of …

Electrochemical Behaviors And Determinations Of Terbutaline Sulfate At Poly Eriochrome Black T Modified Electrode, Yan-Jie Zheng, Hong Yao, Shao-Huang Weng, Hua-Ping Peng, Shi-Wen Gong, Li Huang, Qiang Dai, Xin-Hua Lin

Journal of Electrochemistry

The poly eriochrome black T modified electrode was prepared by electropolymerization. This modified electrode was characterized by scanning electron microscopy(SEM), electrochemical impedance spectroscopy(EIS) and cyclic voltammetry (CV). The electrochemical behaviors of terbutaline sulfate were studied by CV, while the recoveries were measured by differential pulse voltammetry (DPV). The modified electrode shows excellent electrocatalytic characteristics for terbutaline sulfate. In pH 7.0 phosphate buffer solution, the oxidation peak currents obtained by DPV were linear to the terbutaline sulfate concentrations over the range of 1.2x10^-7~2.0x10^-6 mol•L^-1. The detection limit was estimated to be 1.5x10^-8 mol•L^-1 and …

An Stm Study On The Structure Of Pt(100)/Ionic Liquid Omipf6 Interface, Jin Peng, Mian-Gang Li, Li-Qiang Xie, Jia-Wei Yan, Bing-Wei Mao

Journal of Electrochemistry

Potential-dependent structures of Pt(100)/ionic liquid 1-methyl-3-octylimidazolium hexafluorophosphate (OMIPF₆) interface have been studied by electrochemical scanning tunneling microscopy (ECSTM). The cation OMI⁺ forms ordered structure on Pt(100) surface, which exists in a potential region of about 1.2 V. When the potential is more negative than -0.6 V, it can be seen that the ordered structure transforms to disordered structure. When the potential shifts positively to +0.6 V, the desorption of cations OMI⁺ occurs, which indicates that strong electrostatic repulsion is needed to overcome chemical interaction between OMIPF6 and Pt(100) surface, leading to the desorption. The above results …

A Study On The Oxidation Of Hydrogen Peroxide At Au(111) And Au(100) Electrodes, Yong-Li Zheng, Jie Wei, Yan-Xia Chen

Journal of Electrochemistry

The oxidation reactions of hydrogen peroxide (H₂O₂) at Au(111) and Au(100) electrodes in 0.1 mol·L^-1 HClO₄ were investigated by using rotating disk electrode system. It was found that H₂O₂ could be readily oxidized to O₂ at both Au(100) and Au(111) surfaces with the onset potential close to its equilibrium potential. In contrast, the onset overpotential for H₂O₂ reduction was above 0.4 V, while the onset overpotential for H₂O₂ oxidation at Au(100) was ca. 0.1 V more negative than that at Au(111), this is probably …

Lithium-Sulfur (Selenium) Batteries: Interface Issues And Solving Strategies, Nian-Wu Li, Ya-Xia Yin, Yu-Guo Guo

Journal of Electrochemistry

The stable interface is still a challenge for lithium-sulfur (selenium) batteries because of the low conductivity of sulfur (selenium), dissolution of polysulfide (polyselenide), volume expansion of sulfur (selenium), and lithium dendrite growth. This review describers some recent developments in lithium-sulfur (selenium) batteries and highlights our efforts in this field. The possible strategies for building stable interface in the lithium-sulfur (selenium) batteries including nano-restriction effect, chemical bonding, interface adsorption, surface coating, electrolyte optimization, and Lithium anode treatment have been discussed.

Intrinsic Interfacial Property Between High-Voltage Lini0.5Mn1.5O4 Cathode And Electrolyte, Li Li, Jing-Jing Xu, Shao-Jie Han, Wei Lu, Li-Wei Chen

Journal of Electrochemistry

To obtain high energy density, developing high-voltage cathode materials is an effective approach. The cathode/electrolyte interface stability is the key factor for the cycle performance and safety performance of high-voltage lithium ion batteries. It is, therefore, of significant importance to study the stability of cathode/electrolyte interface. However, many reports have shown that at the cathode/electrolyte interface the cathodes were prepared by coating the mixture of active materials with a conductive additive and a binder on an Al current collector. The introduction of additives will interfere the surface morphology and component analyses, resulting in difficulty to acquire the intrinsic information at …

Stm Investigation Of Oxygen Reduction Reaction On Solid Interface In Fuel Cell, Zhen-Feng Cai, Bing Sun, Wen-Jie Jiang, Ting Chen, Dong Wang, Li-Jun Wan

Journal of Electrochemistry

An electrocatalyst for oxygen reduction reaction (ORR) is an important component for fuel cells. An investigation at interfacial electrochemical reactions toward ORR at a molecular scale benefits mechanistic understanding as well as rational design of catalysts. Scanning tunneling microscopy (STM) has been proven to be a powerful tool to monitor chemical reactions and to provide in-situ information about the interfacial electrochemical reactions at a molecular level. This review summarizes the recent STM studies in monitoring the interface processes such as morphological changes, molecular changes, reaction intermediates, and oxidation products. The prospects of future development in this field are outlined.

Investigation On Laser Induced Deposition Of Cu-Based Materials At [Bmim]Bf4/Pt Electrode Interface, Min-Min Xu, Jin-Hua Mei, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

By controlling the negative potential, Cu-based materials were deposited at the [BMIm]BF₄/Pt electrode interface under the laser irradiation. The effects of laser power and irradiation time on the yield of deposition products were studied by using different laser powers and different irradiation time. The product yield could be directly determined by the size of deposition point through the observation from the optical microscope. Further mechanism study combined with the formula deduced that the thermal effect of the laser could make the electrode surface temperature rise 110 degrees, which can promote the occurrence of electrodeposition. By SEM characterization, the …

Chitosan/Nonahydrate Gel Derived Fe-N-Doped Porous Carbon Sheet As High-Efficient Orr Electrocatalyst, Fan-Lu Meng, Xin-Bo Zhang, Jun-Min Yan

Journal of Electrochemistry

The chitosan/nonahydrate gel was used as a precursor to realize the uniform mixture of N-polymer and metal salt. After lyophilization treatment, the gel went through heat treatment and acid etch. Accordingly, the Fe-N-doped porous carbon sheet with homogenous composition and microstructure was prepared. Compared with the commercial Pt/C catalyst, the Fe-N-doped porous carbon sheet exhibited more positive onset potential and half-wave potential, higher current density, and especially, excellent durability. The power density of 318 mW·cm^-2 was obtained in alkaline fuel cell with the Fe-N-doped porous carbon sheet as a cathode catalyst, which is higher than 267 mW·cm^-2 with …

Synthesis Of Ultrathin Co3O4 Nanoflakes Film Material For Electrochemical Sensing, Hui-Juan Wang

Journal of Electrochemistry

Ultrathin cobalt oxide (Co₃O₄ ) nanoflakes film material was synthesized by using an electro-deposited cobalt layer as a raw material through a simple oxidation method and followed by a heat treatment at 350 ^oC. The physical characterizations of the Co₃O₄ nanoflakes film were performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) technologies, and the electrochemical activity was measured by cyclic voltammetry (CV). As a promising material for electrochemical sensing, the as-synthesized ultrathin Co₃O₄ nanoflakes film material exhibited excellent electrochemical activity for H₂O …

Lithium Plating Identification From Degradation Behaviors Of Lithium-Ion Cells, Jian-Bo Zhang, Lai-Suo Su, Xin-Yu Li, Hao Ge, Ya-Kun Zhang, Zhe Li

Journal of Electrochemistry

Lithium plating has huge impact on the lifetime and safety of lithium-ion cells. It is, therefore, necessary to identify lithium plating. In this study, the accelerated stress tests of lithium-ion cells were conducted under different conditions with multi-stress loads. Based on the different effects of the two major aging mechanisms, namely, SEI (Solid Electrolyte Interface) layer growth and lithium plating, on the degradation behaviors, two lithium plating identification methods of resistance-capacity plot and Arrhenius plot were employed. The experimental results revealed that the two identification methods are highly consistent with each other. Furthermore, the origins of capacity loss were distinguished …

Synthesis Of Metal-Containing Phosphines And Their Use In Coordination, Polymer, And Materials Chemistry, Amir Rabiee Kenaree

Electronic Thesis and Dissertation Repository

This thesis describes the investigation of a novel strategy for the synthesis of metal-containing small molecules, polymers, and nanomaterials. In this context, a new family of air-stable, homo- and heterometallic primary, secondary, and tertiary phosphines were prepared via the radical-initiated hydrophosphination reaction of PH₃ with vinylferrocene and/or vinylruthenocene. The full characterization of the phosphines confirmed their targeted structures and proved that the properties of the starting metallocenes are reflected in those of the resulting phosphines.

To study the coordination behavior of this family of phosphines, primary, secondary, and tertiary ethylferrocene phosphines were reacted with Group 6 metal carbonyl adducts …

Creating Functional Materials With Phosphorus, Tyler John Cuthbert

Electronic Thesis and Dissertation Repository

Understanding the relationship between small molecules or polymers and how they affect the properties of materials they compose is the basis of materials science. Using unique and versatile components can impart useful and interesting properties to materials. Here, we aimed to extend this understanding to phosphorus, and the known properties it possesses. This included the production of photopolymerizable coatings containing phosphonium molecules and polymers for antifouling and antibacterial applications. The synthesis and characterization of these phosphonium components was completed and materials were produced utilizing UV curing technology. Addition of these components produced coatings that could resist bacteria attachment and efficiently …

X-Ray Absorption And Emission Studies Of Anodic Titania Nanostructures, Jun Li

Electronic Thesis and Dissertation Repository

One-dimensional (1D) TiO₂ nanomaterials with ordered structure have been extensively applied in various fields, such as photocatalysts, solar cells, supercapacitors and rechargeable batteries, due to the unique structural and functional properties compared to the disordered nanoparticulate forms. Nevertheless, intrinsic disadvantages of TiO₂, such as its large band gap (~3 eV), fast recombination rate of photoexcited electron–hole pairs and insufficient ionic conductivity, severely limit the development of 1D TiO₂ nanomaterials for practical applications. To address the above issues, the scope of this thesis focus on the fundamental understandings of the electronic structure of highly ordered TiO_{2 …}

Synthesis Of Metal-Containing Polymers And Stable Organic Radical-Containing Polymers And Their Use As Advanced Functional Materials, Joseph A. Paquette

Electronic Thesis and Dissertation Repository

The work presented in this thesis details the synthesis and characterization of two different families of multifunctional polymers. The first family involved the incorporation of stable 6-oxoverdazyl radicals into polymer scaffolds. This was originally achieved by the polymerization of the radical precursors, phenyl- and isopropyl-6-oxotetrazanes, followed by post-polymerization oxidation to afford the phenyl- and isopropyl-6-oxoverdazyl polymers. A second methodology involved the direct polymerization of isopropyl-6-oxoverdazyl radicals using ring-opening metathesis polymerization (ROMP) to afford polymers with controlled molecular weights and narrow molecular weight distributions. The polymers were characterized by the close comparison of the physical and spectroscopic properties …

Properties Of High Nitrogen Content Carbon Nitride Thin Films Prepared By A Radio Frequency Magnetron Sputtering Deposition Technique, David Pipher

Electronic Thesis and Dissertation Repository

The properties of carbon nitride (CNx) films deposited onto various substrates using a radiofrequency magnetron sputtering technique were studied as a function of deposition parameters, especially magnetron power, gas pressure and nitrogen content in the plasma. Indium tin oxide (ITO) coated glass and fluorine tin oxide (FTO) coated glass as well as metal substrates (silver and tungsten) were used. Scanning electron microscopy (SEM) was used to study the surface morphology of the prepared CNx films. Energy-dispersive X-ray spectroscopy (EDX) as well as survey X-ray photoelectron spectroscopy (XPS) spectra were used to perform the elemental analysis of the CNx films.

Ultraviolet-visible …

Polyol Induced Partitioning Of Essential Oils In Aqueous Organic Solvent Mixtures, Thomas Delmastro

Seton Hall University Dissertations and Theses (ETDs)

Polyol Induced Extraction (PIE) was developed and patented at Seton Hall University by Drs. John R. Sowa Jr., Wyatt R. Murphy, and Mithilesh Deshpande. It was originally discovered and implemented as a method to recycle and reuse waste acetonitrile during the production shortage in 2008. Through the use of PIE, a solvent mixture containing acetonitrile and water can be separated by employing a polyol mass separating agent, which induces a phase separation. The system is separated into its corresponding aqueous and organic phases, with the organic phase being a highly purified organic liquid. Based on the successful experimental results that …

A Grand Unified Model For Liganded Gold Clusters, Wen Wu Xu, Beien Zhu, Xiao Cheng Zeng, Yi Gao

Xiao Cheng Zeng Publications

A grand unified model (GUM) is developed to achieve fundamental understanding of rich structures of all 71 liganded gold clusters reported to date. Inspired by the quark model by which composite particles (for example, protons and neutrons) are formed by combining three quarks (or flavours), here gold atoms are assigned three ‘flavours’ (namely, bottom, middle and top) to represent three possible valence states. The ‘composite particles’ in GUM are categorized into two groups: variants of triangular elementary block Au₃(2e) and tetrahedral elementary block Au₄(2e), all satisfying the duet rule (2e) of the valence shell, akin to …

Development Of An F-Element Separation Chemistry Using Solid Electrolytes, Kristian Guy Myhre

Doctoral Dissertations

The f‒elements (lanthanides and actinides) have numerous applications and are critically important to many industries, including the energy, security, and medical industries. One of the barriers to increased use and availability of the f‒elements is the difficulty in separating them from each other due to their similar chemistries. This is especially true of the trivalent f‒elements (lanthanides and minor actinides). The development of separation techniques that maximize the differences in the physicochemical properties of the f‒elements is therefore an important area of research. For these reasons, an effort was undertaken to explore the use of solid …

Subtractive Methods To Form Pyrite And Sulfide Nanostructures Of Fe, Co, Ni, Cu And Zn, Kurt W. Kolasinski

Chemistry Faculty Publications

The low Z metals Fe, Co, Ni, Cu and Zn are Earth abundant, i.e. inexpensive, and their sulfides are of low toxicity. This makes them appealing candidates for materials applications requiring semiconductors or, in the case of CoS₂, a metal since they can potentially be produced in large quantities and low cost. Though of great potential little work has explored how subtractive methods can be used to form nanostructured and/or porous structures in, e.g. FeS₂, CoS₂, NiS, Cu₂S and ZnS.

Role Of The Inner Shell Architecture On The Various Blinking States And Decay Dynamics Of Core-Shell And Core-Multishell Quantum Dots, Pooja Bajwa

Graduate Theses and Dissertations

Colloidal semiconductor nanocrystals (quantum dots, QDs) have received much attention in recent years due to their uniquely size-tunable properties leading to a number of promising applications. Some of their most popular applications include their use as fluorescent probes in biology, as electro-optical components and in photovoltaic devices. CdSe-based QDs are particularly important because of their ease of synthesis, high photoluminescence quantum yields (PL QYs) across the whole visible spectrum and their photostabilty. Shelling of core QDs is usually carried out to improve their optical properties, minimize outer environmental effects on their properties, and avoid toxic element exposure to the environment. …

Design And Synthesis Of Novel Octacarboxy Porphyrinic Metal-Organic Frameworks, Jacob A. Johnson

Department of Chemistry: Dissertations, Theses, and Student Research

Metal-Organic Frameworks (MOFs) are a class of nanoporous crystalline materials constructed via the interconnection between metal-ions/inorganic clusters and organic ligands. Since the surface area, pore size and distribution, and chemical functionalities of MOFs are highly tunable via the judicious combinations of inorganic clusters and organic ligands, MOFs have attracted intensive interests for a variety of applications including gas adsorption and separation, catalysis, chemical sensing, and drug delivery among others. Porphyrin based ligands are of particular interest for building functional MOFs due to their unique photo-, electro-, and catalytic properties. In addition, the four-fold symmetry of porphyrin ligands offers an effective …

Design And Synthesis Of Dynamic Covalent Polymer Scaffolds With Controlled Architectures, Emily Annette Hoff

Dissertations

The design and synthesis of functional, controlled polymer architectures is essential to the development of new materials with precise and tailorable properties or applications. The work described in this dissertation focuses on the development of controlled polymer architectures with dynamic linkages for the design of multifunctional materials and surfaces via robust, efficient, and stimuli-responsive strategies.

In Chapter III, a post-polymerization modification strategy based on ambient temperature nucleophilic chemical deblocking of polymer scaffolds bearing N-heterocycle blocked isocyanate moieties is reported. Room temperature RAFT polymerization of three azole-N-carboxamide methacrylates, including 3,5-dimethyl pyrazole, imidazole, and 1,2,4-triazole derivatives, afforded reactive polymer scaffolds …

Electrogenerated Chemiluminescence Study Of Semiconductor Nanoparticles Towards Sensitive Detection Of Biomolecules, Yiliyasi Wusimanjiang

Dissertations

The main focus of this dissertation is to unfold the fundamental aspects of electrogenerated chemiluminescence (ECL) generation from semiconductor nanoparticles (also known as quantum dots or QDs) within different ECL systems. The ECL and photo-physical interactions between the CdTe QDs (λ_emission= ~760 nm) and the CdSe QDs (λ_emission= ~550 nm), as well as the effects of carbon nanotubes on ECL of QDs were separately investigated. Optimum experimental conditions for peptide bond formation on an electrode surface through EDC (1-ethyl-3-(-3-dimethylaminopropyl) carbodiimide hydrochloride)/NHS (N-Hydroxysulfosuccinimide) coupling were also revealed using cyclic voltammetry technique. Based on the information …

Preparation Of Aminoalcohols And Their Application For The Synthesis Of Heterocycles And As Potential Sensors For Nerve Agents, David L. Sellers

Dissertations

Oxazoles and oxazolines are important heterocyclic scaffolds commonly used in pharmaceuticals and optoelectronic materials. Traditionally these heterocyclic compounds are prepared by condensation methodology that suffers from poor reactivity when using electron deficient or sterically crowded reaction partners. Condensation methods also exhibit low tolerance of many functional groups as the reactions typically use strong acids and high temperatures. This dissertation describes an alternate strategy for the formation of these compounds by employing an epoxide opening followed by oxidation to form these heterocyclic compounds.

Epoxide opening reactions with primary aliphatic, allylic, and benzylic amines, aminolysis reactions, often achieve high yields regardless of …

Graphene Quantum Dots Electrochemistry And Development Of Sensitive Electrochemical Biosensor [Hybrid Poster 1-B], Tyler Smith, Alexander Banaszak

Posters-at-the-Capitol

Graphene quantum dots (GQDs) are zero-dimensional material derived from graphene derivatives with characteristics from the structure of graphene with quantum confinement and edge effects possessing unique properties. Intense research activity in GQDs is attributed to their novel physical-chemical phenomena arising from the sp²-bonded carbon core surrounded with edge functional moieties. In this work, GQDs of optimal 5-7 nm size are investigated for their fundamental electrochemical properties and use in electrochemical sensing including enzyme-based glucose biosensor. Glucose oxidase (GO_x) was immobilized on GQDs modified glassy carbon (GC) and the UV-Vis absorption and fluorescence spectroscopy, electron microscopy, cyclic …

Molecular Sensitivity And Selectivity Of Metal Nanoparticles Decorated Graphene As ‘Smart’ Surface-Enhanced Raman Scattering (Sers) Platforms [Hybrid Poster 1-A], Alexander Banaszak, Tyler Smith

Posters-at-the-Capitol

Raman scattering signal enhancement that uses graphene as support, graphene-enhanced Raman scattering (GERS), is a recent phenomenon. It can produce clean and reproducible Raman signals of chemical molecules with significantly enhanced signal intensity in contrast to traditional surface- (SERS) and tip- enhanced Raman scattering (TERS) techniques. While enhancement in SERS and TERS arise due to the electromagnetic mechanism, GERS also relies on a chemical mechanism and therefore shows unique molecular sensitivity and selectivity. In this work, we developed graphene materials decorated with noble metal (silver and gold) nanoparticles for detection of different chemical molecules e.g. methylene blue (MB) and rhodamine …

Evaporation Induced Self-Assembly And Characterization Of Nanoparticulate Films: A New Route To Bulk Heterojunctions, Yipeng Yang

Doctoral Dissertations

Polymer-based semiconducting materials are promising candidates for large-scale, low-cost photovoltaic devices. To date, the efficiency of these devices has been low in part because of the challenge of optimizing molecular packing while also obtaining a bicontinuous structure with a characteristic length comparable to the exciton diffusion length of 10 to 20 nm. In this dissertation we developed an innovative evaporation-induced nanoparticle self-assembly technique, which could be an effective approach to fabricate uniform, densely packed, smooth thin films with cm-scale area from home-made P3HT nanoparticles. Unlike the previous reports of nanoparticle-based film formation, we use a mixture of two solvents so …

Cell Modulation Using Functionalized Nanoparticles, Rui Tang

Doctoral Dissertations

Monolayer functionalized ultra-small gold nanoparticles (AuNPs) provide a versatile platform for applications in cell research. Through rational design of surface ligands, the chemistry of AuNPs are precisely regulated at atomic level. In this dissertation, applications of AuNPs in cell modulation are discussed. The topics are split into two categories. In the first category, functionalized AuNPs are harnessed to generate a robust monolayer on cell culture surface for cell modulation. The proliferation and behavior of different types of cancer cells and normal cells are modulated by tuning the surface ligands of AuNPs. Fate decision of mesenchymal stem cells are also modulated …

Engineering The Nano-Bio Interface Of Gold Nanoparticles For Biomedical Applications, Ying Jiang

Doctoral Dissertations

Gold nanoparticles (AuNPs) have emerged as a promising platform for a myriad of biomedical applications, including sensing, drug delivery, and antibiotics. In this thesis, I have studied and engineered the interface of AuNPs with different biological systems, demonstrating a large variety of biomedical applications by modulation of these interfaces. My research was initially focused on systematically tuning the physicochemical properties of nanoparticles to understand nano-bio interactions at the cellular level. The results demonstrate that size and surface charge of AuNP interact in an interrelated fashion to modulate nanoparticle internalization by cells, providing an engineering strategy for designing nanomaterials for drug …