Chemistry Commons^™

Recent Progress For Fe-N-C Electrocatalysts In Alkaline Fuel Cells, Xin Deng, Heng-Quan Chen, Ye Hu, Qing-Gang He

Journal of Electrochemistry

Fuel cells are highly recommended nowadays due to their intrinsic advantages such as high energy conversion efficiency, nearly no pollution, and convenient operation. With the development of anion exchange membrane, alkaline fuel cells have gone through a renaissance thanks to their superiorities such as faster reaction kinetics, wider choices for both fuels and electrocatalysts. It is essential to find an appropriate electrocatalyst for oxygen reduction reaction (ORR) to improve the performance of alkaline fuel cells. Further commercialization of the widely used Pt-based materials has suffered from disadvantages such as scarcity and high cost. As alternatives to largely investigated Pt-based materials, …

Pt/G-C3N4 Nanosheet For Visible Light-Induced Enhancement Of The Activity For Formic Acid Electro-Oxidation, Yong-Rong Sun, Chun-Yu Du, Guo-Kang Han, Ya-Jing Wang, Yun-Zhi Gao, Ge-Ping Yin

Journal of Electrochemistry

By using graphitic carbon nitride nanosheet (g-C₃N₄ nanosheet) as a support,Pt/g-C₃N₄ nanosheet catalyst was fabricated by microwave assisted polylol process. The nanoparticles size,composition,structure and optical properties of Pt/g-C₃N₄ nanosheet were characterized by TEM,XRD,XPS and UV-Vis diffuse reflectance spectroscopy. Comparing with the catalytic activities toward formic acid electro-oxidation under dark and visible light illumination,the superior activity of Pt/g-C₃N₄ nanosheet catalyst was achieved under visible light illumination. This visible light-driven enhancement in the formic acid performance could be attributed to the plasmon-induced electron-hole separation on g-C₃N₄ with …

Carbon Composite Fe3O4 Nanoparticles Based Electrochemical Sensor For Hydrogen Peroxide Detection, Si-Yu Zhang, Hui-Juan Wang, Shu-Fang Li, Jian-Ying Qu

Journal of Electrochemistry

In this work, a novel hydrogen peroxide electrochemical sensor was constructed with ferroferric oxide (Fe₃O₄) magnetic nanoparticles, which demonstrated good electrocatalytic activity for hydrogen peroxide. There existed a good linear relationship between the concentration of hydrogen peroxide and the oxidation peak current in the range of 1.00 × 10^-6 ~ 1.00 × 10^-3 mol·L^-1 (R = 0.9980) with the detection limit of 6.60 × 10-7 mol·L^-1. The sensor exhibited good anti-interference ability, high reproducibility and stability.

Simulation Of Fractal Growth On Metal Wire Electrode, Li-Feng Ding, Pei-Yuan Mao, Jun Cheng, Yu-Lan Niu, Yu-Hao Wen, Wei Chen

Journal of Electrochemistry

During processes of metal electrodepostion, there exist many complex morphological forms such as dendritic growing in the cathode deposited metal edge, which will seriously affect the quality of the electrodeposited product and current efficiency during machining. Investigations on dendritic crystal growing process and morphology could help controlling growth of electrolysis precipitate. In this work, Python and Matlab softwares were used, and the model of parallel electrode electrodeposition was established based on the diffusion-limited aggregation (DLA) model. By analyzing the law of fractal growth at different conditions of the particles number, probability, electrode spacing, the movement step length and orientation drift, …

Lead Modified Nanoporous Platinum Electro-Catalysts For Formic Acid Oxidation, Yuan-Yuan Zhang, Qing-Feng Yi, Ge-Kun-Kun Zuo, Tao Zou, Xiao-Ping Liu, Xiu-Lin Zhou

Journal of Electrochemistry

Platinum (Pt) catalysts modified by other suitable metals significantly enhance their electrochemical activities for formic acid oxidation. In this work, a titanium-supported nanoporous network platinum (nanoPt/Ti) electrode was prepared using a hydrothermal method. The as-prepared nanoPt/Ti electrode was modified with a certain amount of lead by using cyclic voltammetry for different scan cycle numbers (n), namely, n = 10, 15, 20 and 30, to synthesize the novel lead-modified nanoporous Pt (nanoPb_(n)-Pt/Ti) electrodes. Electro-oxidation of formic acid on these electrodes was studied with cyclic voltammetry (CV), chronoamperometry and chronopotentiometry in sulfuric acid solution. CV curves showed that both nanoPt/Ti …

Game Of Frontier Orbitals: A View On The Rational Design Of Novel Charge-Transfer Materials, Maxim Vadimovich Ivanov, Scott A. Reid, Rajendra Rathore

Chemistry Faculty Research and Publications

Since the first application of frontier molecular orbitals (FMOs) to rationalize stereospecificity of pericyclic reactions, FMOs have remained at the forefront of chemical theory. Yet, the practical application of FMOs in the rational design and synthesis of novel charge transfer materials remains under-appreciated. In this Perspective, we demonstrate that molecular orbital theory is a powerful and universal tool capable of rationalizing the observed redox/optoelectronic properties of various aromatic hydrocarbons in the context of their application as charge-transfer materials. Importantly, the inspection of FMOs can provide instantaneous insight into the interchromophoric electronic coupling and polaron delocalization in polychromophoric assemblies, and therefore …

Co3(Hcoo)6@Rgo As A Promising Anode For Lithium Ion Batteries, Heng Jiang, Jing-Min Fan, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

Metal–organic framework(MOF) is a kind of novel electrode materials for lithium ion batteries. Here, a composite material Co₃(HCOO)₆@rGO was synthesized for the first time by in situ loading of Co₃(HCOO)₆ on rGO (reduced oxide graphene) through a solution chemistry method. As an anode material for lithium ion batteries, it exhibited an excellent cycle stability as well as a large reversible capacity of 926 mAh·g^-1 at a current density of 500 mA·g^-1 after 100 cycles within the voltage range of 0.02 ~ 3.0 V vs. Li/Li⁺ with a good rate capability. …

Dft Study Of Water Assisted Hydrogen Dissociation On Gold Nanoparticles, Jia-Li Chen, Xia-Guang Zhang, De-Yin Wu, Zhong-Qun Tian

Journal of Electrochemistry

The gold nanoparticles (GNPs) show special activity toward hydrogen (H₂) dissociation, comparing with bulk gold. Such activity is significantly affected by the existence of water. To inspect the influence of water on GNPs catalyzed H₂ dissociation, we carried out density functional theory (DFT) calculations along the reaction paths for water clusters (H₂O)_m (m = 1, 2, 3, 7) assisted H₂ dissociation on gold clusters (Au_n^δ, n = 3 ~ 5; δ = 0, 1). Our calculated results show that water benefits to the H₂ dissociation. The dissociation mechanism varies …

Influences Of Fec-Based Electrolyte On Electrochemical Performance Of High Voltage Cathode Material Li2Copo4F, Zhi-Gang Wang, Wei-Min Zhao, Hong-Chun Wang, Min Lin, Zheng-Liang Gong, Yong Yang

Journal of Electrochemistry

The effects of fluoroethylene carbonate (FEC) as co-solvent on the electrochemical performance of high voltage cathode material Li₂CoPO₄F are investigated. Compared with traditional carbonate based electrolyte (1 mol·L^-1 LiPF₆ EC/DMC (1:1, m:m)), the FEC/DMC based electrolyte can significantly improved the electrochemical performance of Li₂CoPO₄F. After 100 cycles between 3V and 5.4 V at 1 C rate, the capacity retention of Li₂CoPO₄F electrode in 1 mol·L^-1 LiPF₆ EC/DMC (1:1, m:m) was 52.6 % , while that in the EC/DMC based electrolyte was only 14.5 %. …

Preparations And Electrochemical Performances Of Carbon Coated Silicon/Graphite Composites, Tian-Yi Gao, Zheng-Liang Gong

Journal of Electrochemistry

In this work, the carbon coated silicon (Si@C) composite materials were synthesized based on the industrial silicon powder (600 meshes) via a high energy ball milling combing with in-situ carbon coating (carbonization) method. The Si@C/graphite (Si/C) composite anode materials were prepared by a simple mechanical ball-milling approach. The effects of carbon coating and the ratio of Si to graphite on electrochemical performances of Si/graphite composite materials were investigated systematically. Compared with the nano-Si/graphite composites, the Si/C composites showed higher reversible capacity, better rate capability and cycle performance. The Si@C materials composited of amorphous carbon and crystal silicon with the primary …

Preparation And Electrochemical Performance Of Ag-Tio2-Mno2 Composites, Ling-Xiao Zhang, Hui-Hui Zhao, Li-Juan Zhang, Yu Fu

Journal of Electrochemistry

The silver-titanium dioxide  co-modified manganese dioxide (Ag-TiO₂-MnO₂) cathode material was prepared through high temperature solid state reaction. The microstructure, phase composition and electrochemical performance of the prepared samples were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDS), Cyclic voltammetry (CV), galvanostatic discharge and electrochemical impedance spectroscopy (EIS). Results showed that the unmodified and Ag-TiO₂ modified MnO₂ samples both exhibited β-MnO₂ structurebut with different morphologies. The EDS mapping results revealed that Ag was uniformly dispersed on the surface of …

Chemical Investigation Of Bioactive Marine Extracts, Selam Hagos

USF Tampa Graduate Theses and Dissertations

Natural products have been a fundamental source of medicinal scaffolds for decades; with sixty percent of marketed drugs. Many synthetic chemists are focused on synthesizing potent and nontoxic compounds for pharmaceutical targets, however, nature is still proving to be a source of new bioactive compounds. Produced by the host organism for defense, reproduction and communication, secondary metabolites also demonstrate promising bioactivity against human pathogens. Hence, natural product chemists continue their quest for new leads.

As a continuation of these efforts, this thesis attempts to explore fungi and sponges for new chemistry, and ultimately, new drug candidates. Antarctica is largely untapped; …

Super‐Resolution Imaging Of Amyloid Structures Over Extended Times By Using Transient Binding Of Single Thioflavin T Molecules, Kevin Spehar, Tianben Ding, Yuanzi Sun, Niraja Kedia, Jin Lu, George R. Nahass, Matthew D. Lew, Jan Bieschke

Electrical & Systems Engineering Publications and Presentations

Oligomeric amyloid structures are crucial therapeutic targets in Alzheimer's and other amyloid diseases. However, these oligomers are too small to be resolved by standard light microscopy. We have developed a simple and versatile tool to image amyloid structures by using thioflavin T without the need for covalent labeling or immunostaining. The dynamic binding of single dye molecules generates photon bursts that are used for fluorophore localization on a nanometer scale. Thus, photobleaching cannot degrade image quality, allowing for extended observation times. Super‐resolution transient amyloid binding microscopy promises to directly image native amyloid by using standard probes and record amyloid dynamics …

A Study Of Pulse Electrodeposition On Suppressing The Formation Of Lithium Dendrite, Wen-Jun Guo, Zi-Qiong Li, Ruo-Hao Ke, Dong-Fang Niu, Heng Xu, Xin-Sheng Zhang

Journal of Electrochemistry

A pulse charge method was used to suppress the formation of lithium dendrite on the copper electrode in 0.5 mol·L^-1 LiBr/propylene carbonate (PC) electrolyte. The surface variation of lithium deposition was investigated by scanning electron microscope and impedance measurement. The SEM test showed that the lithium dendrites were formed on the copper electrode during the traditional process of electrodeposition. However, the formed dendrite was suppressed by pulse charge method. The results of the impedance measurement confirmed that the pulse electrodeposition could suppress the dendrite under the optimized duty ratio (0.5). The long single pulse deposition time decreased the resistance …

Chemical Stability Investigations Of Catalyst Layer In Pemfc, Yan-Yan Gao, Ming Hou, Yong-Yi Jiang, Dong Liang, Jun Ai, Li-Min Zheng

Journal of Electrochemistry

This work was intended to study the effect of free radicals on the chemical stability of catalyst layer via ex situ accelerated stress test (AST). Fenton reagent was used as the free radical provider in this research. Apart from the decomposition of Nafion in catalyst layer, the agglomerated Pt nanoparticles and the corroded carbon support were also observed after being treated in Fenton reagent for 100 h. Firstly, the existence of fluoride (F) ions evidenced the chemical decomposation of Nafion after being attacked by trace radical species, which was supported by the intensity decrease in the C-F stretching and vibration …

Hydrophilic Interaction Liquid Chromatography-Electrospray Ionization Mass Spectrometry For Therapeutic Drug Monitoring Of Metformin And Rosuvastatin In Human Plasma, Nikolaos Antonopoulos, Giorgos Machairas, George Migias, Ariadni Vonaparti, Vasiliki Brakoulia, Constantinos Pistos, Dimitra Gennimata, Irene Panderi

Chemistry Faculty Publications

In this work a hydrophilic interaction liquid chromatography/positive ion electrospray mass spectrometric assay (HILIC/ESI-MS) has been developed and fully validated for the quantitation of metformin and rosuvastatin in human plasma. Sample preparation involved the use of 100 µL of human plasma, following protein precipitation and filtration. Metformin, rosuvastatin and 4-[2-(propylamino) ethyl] indoline 2 one hydrochloride (internal standard) were separated by using an X-Bridge-HILIC BEH analytical column (150.0 × 2.1 mm i.d., particle size 3.5 µm) with isocratic elution. A mobile phase consisting of 12% (v/v) 15 mM ammonium formate water solution in acetonitrile was used for the separation and pumped …

Mechanistic Studies Of Palladium-Catalyzed Aminocarbonylation Of Aryl Chlorides With Carbon Monoxide And Ammonia, Justin Y. Wang, Alexandra E. Strom, John F. Hartwig

Chemistry: Faculty Publications

Mechanistic information on a reliable, palladium-catalyzed aminocarbonylation of aryl chlorides with ammonia is reported. The reaction occurs with ethylene complex 1 as catalyst, and mechanistic information was gained by isolation of catalytic intermediates and kinetic measurements, including the first mechanistic data on the oxidative addition of aryl chloride to a palladium(0) complex in the presence of CO. Arylpalladium and phenacylpalladium halide intermediates were synthesized, and kinetic measurements of the formation and reactions of these intermediates were undertaken to determine the mechanism of the oxidative addition of aryl bromides and chlorides to a Pd(0) dicarbonyl compound in the presence of CO …

Rearrangements Of Fluorinated Cyclopropylamines As A Novel Approach Toward Fluoroalkene-Based Peptidomimetics, Igor Mezentsev, Vera Zaborova

The International Student Science Fair 2018

Organofluorine molecules have been widely applied in various research fields because of the unique properties of fluorine atoms. One type of fluorinated compounds is fluoroalkene-based peptidomimetics which are structurally similar to amide-containing compounds. They have been prepared to improve the pharmaceutical properties such as bioactivity, target specificity, and metabolic stability of the bioactive amides.

We suggested a new way of synthesizing fluoroalkene-based peptidomimetics through 2-fluoro-2-halocyclopropylamines, which provides an effective way toward fluoroalkene-based peptidomimetics with increased functional group tolerance and possibility of convergent synthesis.

Shaping Electrons’ Bremsstrahlung Beam Using Two Slit Collimators, Kh.Т. Trobov, N.B. Ferapontov, М.G. Tokmachov

Scientific Journal of Samarkand University

On the basis of a heterogeneous model of the structure of polymeric sorbents, the supramolecular properties of polymer gels are shown. It is established that the composition of the polymer gel consists of a polymer solution and an external solution. It has been proved that the amount of water sorbed by the polymer is a function of the water activity in the outer phase.

Effect Various Factors On Multiple Reaction Activity Of 2-Thioxopirimidine-4-Ones On Reaction Of Alkylation., К.А. Zahidov, Z.U. Samarov, O.I. Urinov, U.М. Norkulov

Scientific Journal of Samarkand University

Alkylation of polident anion of 6-methyl (fhenil)- 2-thioxopyrimidine-4-one with “soft” methyl iodide) and “hard” (methyltozilate) alkilation agents have been systematically studied. It was shown the nature of solvents influnce on reactivity and the direction of alkylation.

Steric Effects Of Alkyl Ammonium Salts On The Combustion Of Exchanged Smectite Clays, Celeste A. Keith

Electronic Theses and Dissertations

Bomb calorimetry was explored as a new method for determining the cation exchange capacity (CEC) of clays. Smectite clays were modified with several alkyl ammonium salts varying in number of carbons and the spatial orientation of the carbons about the central nitrogen atom. The clays used, standards purchased from the Source Clay Repository, have CECs of 44, 80, 88, and 120 meq/100 g. Theoretically, the combustion energy of the organo-clays should be approximately the same for each salt. Any differences in energy would be due to the different structures of the salts and how they are oriented in the interlamellar …

Kinetic Solvent Viscosity Effects As Probes For Studying The Mechanisms Of Enzyme Action, Giovanni Gadda, Pablo Sobrado

Chemistry Faculty Research & Creative Works

The study of enzyme reaction mechanisms is fundamentally important to our understanding of biochemistry, cellular metabolism, and drug development. This Perspective focuses on the use of kinetic solvent viscosity effects (KSVEs) to study enzyme reactions. This technique is easily implemented and uses steady-state kinetic analyses to probe whether substrate binding is diffusion-controlled and whether product release is the rate-limiting step in the catalytic cycle. In addition, KSVEs can identify isomerization steps that are important for catalysis. The use of KSVEs in combination with other techniques, such as kinetic isotope effects, pH effects, and site-directed mutagenesis, can provide a detailed view …

Feco2o4 As An Anode Material For Lithium Ion Batteries, Chelsea Wong

The International Student Science Fair 2018

Lithium ion batteries (LIBs) are commonly found in many portable electronic appliances due to their ability to be rechargeable. Currently, commercial anodes in Li-ion batteries (graphite) have a theoretical capacity of around 372 mAh/g, while FeCo2O4 that will be investigated as the anode material has a theoretical capacity of 901.985mAh/g, more than double of the current commercial anode’s capacity. Earlier work done by Sharma et al also showed that FeCo2O4 has a very promising initial capacity of 827mAh/g. As such, the engineering goal is to produce a battery that will have a higher capacity than the current commercial Li-ion batteries …

Removal Of Pb2+ Ions From Consuming Water Using A Fabricated Water Filter For Home Use, Pantaree Sodkhoksoong, Papidchaya Chanpong, Thunyarus Rodsawatchuchoke

The International Student Science Fair 2018

Lead contamination in water is one of the worldwide concerned environmental problems. For example, lead leaking from pipe corrosion and solder has been found contaminated in consuming water in many U.S. areas. The uncontrolled release of effluents containing lead from various industries has also caused lead-contaminated water in Thailand. Exposing to lead-contaminated water can lead to serious symptoms (e.g. fatigue, headaches, abdominal pain, irritability, depression, and seizures) or even death. Therefore, the elimination of lead ions (Pb²⁺) from consuming water or from effluents before releasing into the environment is necessary. The selection of adsorbents and the fabrication of …

Glucosamine From Hydrolysis Of 3d Printing Chitosan For Osteoarthritis Treatment, Ruj Dansriboon, Laphon Premcharoen

The International Student Science Fair 2018

This project aims to introduce a new way for osteoarthritis treatment which is expected to increase in the future. Glucosamine is the main subject for a treatment, which can be derived by hydrolyzing chitosan. This project also includes extraction of chitosan from shrimp waste to make a worthy use of food waste from industry. In this project, 3D printer is applied to print chitosan gel since 3D printing is adjustable to form various shapes of the gel.

The research process begins with the extraction of chitosan from shrimp shells. For the next step, the percent of deacetylation of chitosan was …

An Entirely New Molecular Glue For Mof Using Unusual Structural Transformation Of A Coordination Polymer, Sukwoo Jung, Hangyeol Kim, Junseok Ahn

The International Student Science Fair 2018

In this research, an entirely new molecular glue is reported. This ‘coordination polymer glue’ is synthesized from zinc metal and BDC-NPE(2,5-bis{4-[1-(4-nitrophenyl)ethylamino]butoxy}terephthalic acid). Molecular glue transforms from 1D coordination polymer to a 3D cross-linked framework, resulting in a phase change of solution to solid. The carboxylate group of this glue makes the preformed MOF bind to its framework. Therefore, when the solution of molecular glue is mixed with preformed MOF powder and heated, homogeneous and thin MOF film – MOF/ZnNPE film – is fabricated. The film is irrelevant to the kind of its substrate, and its thermal stability was enhanced in …

The Effect Of Semiconductor Materials On Solar Cell Efficiency, Shivam Vohra

The International Student Science Fair 2018

The purpose of this project was to increase the efficiency of solar cells through the use of quantum dots and nanoparticles. These substances would increase the efficiency of the semiconductor. The research hypothesis stated that if lead iodide was applied to the semiconductor, then the average voltage, amperage, power, and efficiency of the solar cells would increase. The procedure for this project involved creating a lead iodide and titanium dioxide mixture with dimethylformamide, ethanol, acetylacetone, and Triton X-100 in an autoclave. Then, two milliliters of each solution were applied to cadmium selenide quantum dots to make four different solutions. Each …

New Platinum(Ii) And Rhenium(I) Complexes Of "Linear" Chelate Ligands Terminated With Pyridyl Or Imidazolyl N-Donor Groups, Himali Kokila Ranasinghe Pilana Vithanage

LSU Doctoral Dissertations

The overall goal of this dissertation research is to design, synthesize, and study new Pt(II) and Re(I) complexes relevant to biomedical applications. One of the projects involves the assessment of the interactions of bulky tridentate carrier ligands with a bound guanine nucleobase derivative (G) in platinum complexes, with a goal of developing chemistry potentially relevant to active anti-cancer Pt drugs. In another project, the fac-[Re^I(CO)₃]⁺ core is used to prepare novel Re(I) complexes with the purpose of developing new linking chemistry relevant to ^99mTc and ¹⁸⁷Re radiopharmaceuticals. This research explores …

Production Of Trimethylaluminum (Me3al) With Counterfeit Refrigerant Chloromethane (R-40), Reactivity Of Me3al With Refrigerant Oils And Methods To Deactivate Me3al, Zhichao Chen, Rudy Luck

Michigan Tech Publications, Part 1

Reactions between Al containing materials and counterfeit refrigerant chloromethane (R-40) were investigated under various conditions. The addition of Mg effected a reaction indicating that trimethylaluminum may have been produced in the reaction. A different study involving Al-foil, AlCl₃ and chloromethane resulted in cracks detected on the Al-foil which reduced in weight by 19% and methane was detected. Studies conducted either at room temperature or at 80°C with two other genuine refrigerants, R-142b (1-chloro-1,1-difluoroethane) and R-133a (2-chloro-1,1,1-trifluoroethane) did not form organoaluminum compounds. Several commercially available refrigerant oils were subjected to Me₃Al. Only polyester oil resulted in a decrease …

Quantitative Proteomics To Support Translational Cancer Research, Melissa Hoffman

USF Tampa Graduate Theses and Dissertations

Altered signaling pathways, which are mediated by post-translational modifications and changes in protein expression levels, are key regulators of cancer initiation, progression, and therapeutic escape. Many aspects of cancer progression, including early carcinogenesis and immediate response to drug treatment, are beyond the scope of genetic profiling and non-invasive monitoring techniques. Global protein profiling of cancer cell line models, tumor tissues, and biofluids (e.g. serum or urine) using mass spectrometry-based proteomics produces novel biological insights, which support improved patient outcomes. Recent technological advances resulting in next-generation mass spectrometry instrumentation and improved bioinformatics workflows have led to unprecedented measurement reproducibility as well …