Chemistry Commons^™

Preparation And Properties Of Separator For Lithium-Ion Battery, Xu-Mei Ren, Feng Wu, Chuan Wu, Han-Jun Li, Xue-Jie Huang

Journal of Electrochemistry

Lithium-ion batteries are well adapted to the new multimedia applications. PP/PE based microporous film is commonly used as separator in commercial lithium ion batteries. Herewe report a microporous film which is superior to the commercial available separator. The microporous PVDF polymer separators were prepared by the phase inversion process. The pore size of the separator is Φ 7 μm , and it's porosity is 75 %. The membrane in LiPF₆-EC/DEC showedhigh ionic conductivity (above 10^-3 S/cm at room temperature), and good mechanical properties(10³ kg/cm²). The half-cells consisted of Li/PVDF separator/MCMB showed excellent cyclingcharacteristics and …

The Effect Of Calcium On The Properties Of Molybdenum Nitride Electrode, Yun-Gui Zhu, Xue-Liang Li, Dao-Rong Lu, Jian-Bo He, Ji-Huai Xia

Journal of Electrochemistry

The effect of calcium on the properties of molybdenum nitride film electrode wasstudied by using XRD, SEM and cyclic voltammetry. The results show that the specific electriccapacity and the voltage operating range of electrode vary with the concentration of additive in thedipping solution. At the optimum concentration of additive in the dipping solution, the specificelectric capacity of the electrode is 2.1 times as large as that of the electrode prepared in the dipping solution without additive, and the voltage operating range of electrode is increased by 0.11 V. The active mechanism of calcium on the properties of film electrode suggested …

Corrosion Behavior Of Titanium In Fgd System, J-C Lin, T-L Chang, C-T Dung, S-L Lee, S-D Chyou, S-D Guo

Journal of Electrochemistry

In-situ corrosion test of titanium in flue gas desulfurization(FGD) system has been studied. Specimens of commercial Ti alloy have been put in four different locations (i. e , cooler, pre-scruber, absorber and heater) of the FGD system for 271 days. The corrosion rate is very low (i.e.<1 mpy) in all locations. Almost no corrosion can be found in the prescruber(0 mpy), but a sensible corrosion rate is estimated in the heater (0.58 mpy). Examination through SEM, all the specimens are subject to pitting corrosion except those in the prescruber. ESCA analysis indicates that the surface film for the specimen in prescruber is calcium carbonate, but titanium nitrate for the specimen in heater. Cyclic anodic potentiodynamic polarization (CAPP) of titanium in aerated and deaerated green solution provides an interpretation on the corrosion behavior of the titanium in the FGD system.

Electrochemical Studies On The Intermetallic Interaction In Binuclear Ruthenium(Ⅱ) Complexes, Hong Li, Hui Chao, Liang-Nian Ji, Xiong Jiang

Journal of Electrochemistry

The electrochemical characteristics and intermetallic interaction of symmetrical binurclear ruthenium (ll) complexes [Ru2 : (bpy)₂Ru(DIPB)Ru(bpy)₂(ClO₄)₄ and Ru2-2H : (bpy)₂Ru(DIPB - 2H)Ru(bpy)₂(ClO₄)₂]containing dinuclear ligand 2,2-bipyridine (bpy) andbridging ligand 1,4-di[2-imidazo[4,5-f][1,10] phenanthroine ]benzene(DIPB) or 1,4-di[2-dehydrogen-imidazo[4,5-f][1,10]phenanthroine]benzene(DIPB-2H) on a platinum electrode havebeen investigated using cyclic voltammetry, cyclic ac voltammetry and differential capacitancetechniques,etc. In acetonitrile solutions with a concentration of 0.1 mol/L TBAP, the centraruthenium ions in Ru2 and Ru2-2H complexes have shown a single 2e reversible oxidationreduction wave on the cyclic voltammograms with basically the same formal potentials of Ru2-2H …

Comparison In Surface Enhanced Raman Scattering On Salicylideneamine Between Silver And Gold Colloid And Silver Mirror Substrate, Bing Zhao, Yukihiro Ozaki

Journal of Electrochemistry

This work studied the potential difference and galvanic currents on particulate contamination of the abrasive on the patterned surface and on corrosion behaviors of TiN and W. The polarization curves of TiN and W were, respectively, obtained in 0.01mol/L KNO₃ solutions in the absence and presence of three typical oxidants (H₂O_2, KIO₃, Fe(NO₃)₃) by DC polarization technique. The corrsion potentials and galvaniccurrents were measured when TiN and W were placed in a specially designed electr-chemical cell to form electro-couple. The preliminary results revealed that the corrosionrate of TiN-W electro-couple significantly …

Performance Of A Direct Methanol Fuel Cell, Zhao-Bin Wei, Jian-Guo Liu, Ya-Guang Jiao, Wei-Jiang Zhou, Wen-Zhen Li, Li-Kang Chen, Qin Xin, Bao-Lian Yi

Journal of Electrochemistry

A direct methanol fuel cell with 9cm² active area consists of Pt-Ru/C anode ,Pt/Ccathode and Nafion 115 membrane. The effect of operating conditions: methanol solution concentration, oxygen pressure and cell temperature on the cell performances was investigated. The results show that performance of single cell was enhanced by increasing oxygen pressure and celltemperature ,and a maximum power density 75 mW/cm² was obtained in the range of 250-300mA/cm² current density, 0.2 MPa oxygen pressure, 1.0 mol/L methanol concentration and 75 ℃ cell temperature. When cell operating at room temperature, a relatively low, but a stable performance of cell …

The Dependence Of Relative Enhancement Of Sers Bands On Temperature, Ling Huang, Jian Shen, Tsing Yu, Qing-Jin Meng

Journal of Electrochemistry

The adsorption and binding behavior of 2,5-dimercapto-1,3,4-thiadizole(DMTD) on silver surface was studied by near-infrared Fourier Transfer surface enhanced Raman scattering(NIR FT-SERS) technique. It was found that the relative intensities of the SERS bands change regularly with the increasing of temperature, which suggests the transformation of the tautomers or the re-orientation of DMTD molecules in the surface layer.

Study On Corrosion Resistance Of Electroless Nickel Composite Coatings, Tsong-Jen Yang, Meng-Feng Jou

Journal of Electrochemistry

The eletroless nickel composite coating was prepared by uniform dispersion of diamond (or PTFE) particles throughout electroless nickel deposition. Corrosion resistance of composite coating in 3.5% NaCl aqueous solution was investigated by electrochemical analysis, dipping test and salt spray test. The results showed that the corrosion resistance of composite coating was inferior to that of electroless nickel coating if small amount of particles was added to the composite coating. Microsturctural analysis by SEM, AES, XRD, and EPMA indicated that the distribution of phosphorus is not homogeneous in the composite coating. The phosphorus_rich region acts as microcathode, however, the phosphorus-lean region …

Preparation Of Ti-Based Nanocrystalline Tio2 Film Electrode With High Activity, Dao-Bao Chu, Guang-Xia Shen, Xing-Fu Zhou, Chang-Jian Lin, Hua-Shui Lin

Journal of Electrochemistry

The potentiostatic electrosynthesis of Ti(EtO)₄ was studied by anodic dissolution of metal titanium(TA1) in solution of 0.005 mol·L^-1 (EtO)₄NBr in the ethanol (AR) in the presence negligible CH₃COCH₂COCH₃. The Ti-based nanocrystalline TiO₂ Film electrode (Ti/nano-TiO₂) was prepared by sol-gel method. By TEM, SEM and XRD, it has been shown that the anatase particle of TiO₂ was 10～35 nm in diameter and the film was 0.5 μm in thickness. The nanocrystalline film was composed of a three-diminsional network of interconnected particles. Reodx behavior and electrocatalytic activities of …

New Progress In Studies Of Lithium Nickel Oxide As Positive Electrode Materials Of Lithium Ion Batteris, Han-San Liu, Yong Yang, Zhong-Ru Zhang, Zu-Geng Lin

Journal of Electrochemistry

Lithium nickel oxide as the positive electrode of lithium ion batteries has aroused more and more interests.This paper reviews the recent reserches on synthesis and element-substitution of LiNiO₂ cathode material,and summarizes the intrinsical relationship between properties and sturcture of the material.The developments of new synthesis methods and mutilsubstitution of the material are expecting to be studied in the future research.

Electrochemistry Characteristic Of Carbon Steel Under Biofilm And Sulfide Film, Ze-Hua Dong, Xing-Peng Guo, Jia-Shen Zheng, Li-Ming Xu

Journal of Electrochemistry

Wire Beam Electrode (WBE) made of Q235 carbon steel was applied to study theheterogeneous corrosion beneath biofilm formed by Sulfate Reducing Bacteria (SRB) in cultureand sulfide film in solution with 1% NaCl and 300 mg/L⋅S^2-. The potential, galvanic density mapping, as well as polarization curve and Electrochemical Impedance Spectrum (EIS) were measured to predict the localized corrosion under biofilm and sulfide film. As a result, the mappingshowed the potential fluctuation on the WBE suface decreased over time due to the conductivityof the biofilm and sulfide film. Therefore, the potential mapping could not be a criterion of localized corrosion …

The Effect Of Preparation Condition On The Photoelectrochemical Performance Of Both The Pani Film And Tio2-Pani Composite Film On Au, Huai-Guo Huang, Hong-Ping Zhang, Zhi-Xin Zheng, Yan-Yan Xi, Ling-Ling Wu, Zhong-Hua Lin

Journal of Electrochemistry

Both the PANI (polyaniline) film and TiO₂-PANI composite film on the PATP(paminothiophenol)/Au substrate were obtained under different preparation condition by electrochemical methods, and their photoelectrochemical performances were alo studied. The resultsshowed that the photoelectrochemical performances of the films depend deeply on the comditionsof preparation. The self-assembling of PATP favors the adhesion of PANl. The partially-oxidizedPANI has a greater photoelectrochemical response than that of the reduced PANI and oxidized PANl. There is an optimum of film thickness for the photoelectrochemical performance of PANI film. Heat treating is in favor of the photoelectrochemical performance of TiO₂, but decreases …

Efficient New Ribozyme Mimics: Direct Mapping Of Molecular Design Principles From Small Molecules To Macromolecular, Biomimetic Catalysts, William C. Putnam, Andrew T. Daniher, Bobby N. Trawick, James K. Bashkin

Educator Preparation & Leadership Faculty Works

Dramatic improvements in ribozyme mimics have been achieved by employing the principles of small molecule catalysis to the design of macromolecular, biomimetic reagents. Ribozyme mimics derived from the ligand 2,9-dimethylphenanthroline (neocuproine) show at least 30-fold improvements in efficiency at sequence-specific RNA cleavage when compared with analogous o-phenanthroline- and terpyridine-derived reagents. The suppression of hydroxide-bridged dimers and the greater activation of coordinated water by Cu(II) neocuproine (compared with the o-phananthroline and terpyridine complexes) better allow Cu(II) to reach its catalytic potential as a biomimetic RNA cleavage agent. This work demonstrates the direct mapping of molecular design principles from small-molecule …

Quantification Of Nanomolar Superoxide In Aqueous Solution : Flow Injection Analysis Using The Chemiluminescent Reagent Mcla., Nathan Boland

Honors Theses

A flow injection system using the chemiluminescent reagent 2-methyl-6-(4methoxyphenyl)- 3,7-dihydroimidazo[1,2-a]pyrazin-3-one (MCLA) was used to quantify aqueous concentrations of superoxide. Stock solutions of superoxide were produced by photolysis of a solution of 2-propanol and benzophenone. The concentration of superoxide was quantified in the stock solutions by direct measurement of the absorbance at 240 nm. Quantified additions of superoxide to the flow injection analysis system reacted with MCLA at pH 5.1 demonstrated a detection limit of 0.074 nM superoxide. Selective superoxide detection was confirmed by pH-dependent decay of superoxide, which was in excellent agreement with published rates.

Metal Ion Stabilization Of G-Tetrads Containing 6-Thioguanosine, Julia Drees

Honors Theses

As alternative structures to the double helix, G-tetrads are thought to occur in DNA with many repeating deoxyguanosines (dG). These tetrads have one dG on each corner of a plane and can stack into tetraplexes that can be aptamers and may be found in telomeres. G-tetrads are destabilized by incorporation of 6-thiodeoxyguanosine (?sdG). Addition of metal ions that bind sulfur may stabilize these ?sdG-tetrads. We have carried out a survey of metal ion titrations into ?sG. Stable ?sG:MD? complexes were found for Hg2? (2:1), Cd2? (4:1), Ag2? (0.7:1) and Pt2? (thought to be 2:1). UV/Visible spectrophotometry indicates that G-tetrads containing …

Photochemical Generation And Intramolecular Chemistry Of 2-Hydroxy-2-Methylpropylidene, Robin Farlow

Honors Theses

2-(1a,9b-Dihydro-lH-cyclopropa[l]phenanthren-1-yl)-propan-2-ol was synthesized by two different but related synthetic routes and characterized by melting point, IR GC/MS, CHN, and NMR spectroscopy. Photolysis of the alcohol in benzene d-6 led to the formation of 2-butanone, 1-methylcyclopropanol, and 2,2-dimethyloxirane in a 26:10:1 ratio via 2-hydroxy-2methylpropylidene, a novel ?-hydroxycarbene. These products are a consequence of intramolecular insertions of the carbene into C-C, C-H, and O-H bonds. Molecular orbital calculations performed at the Becke-3LYP/6-31G(d) level indicate that the singlet form of this carbene is more thermodynamically stable than the triplet. Furthermore, the transition states to the three products from the singlet species were modeled …

Nucleation Of Water And Methanol Droplets On Cations And Anions: The Sign Preference, K.J. Oh, G.T. Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The barrier height to cation- and anion-induced nucleation to produce water and methanol droplets are calculated by means of an umbrella-sampling Monte Carlo method. The computer simulation corroborates the century-old finding of Wilson that the anion is a better nucleator to produce water droplets than the cation having the same magnitude of charge, even without the presence of external electric field. The simulation also shows that the cation is a better nucleator to produce methanol droplets than the anion.

Effects Of Eluent Ph And Different Types Of Acidic Modifiers On The Retention And Electrospray Ionization Efficiency Of Basic Analytes In Lc-Esi-Ms., Unita L. Peri-Okonny

Seton Hall University Dissertations and Theses (ETDs)

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The Partition/Adsorption Model For The Description Of The Retention Mechanism In Reversed Phase Liquid Chromatography, Tarun S. Patel

Seton Hall University Dissertations and Theses (ETDs)

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Anionic Photofragmentation Of Co: A Selective Probe Of Core-Level Resonances, Wayne C. Stolte, D. L. Hansen, Maria Novella Piancastelli, I. Dominguez-Lopez, A. Rizvi, Oliver Hemmers, H. Wang, Alfred S. Schlachter, M. S. Lubell, Dennis W. Lindle

Environmental Studies Faculty Publications

Anion-yield spectroscopy using x rays is shown to be a selective probe of molecular core-level processes, providing unique experimental verification of shape resonances. For CO, partial anion and cation yields are presented for photon energies near the C K edge. The O^- yield exhibits features above threshold related only to doubly excited states, in contrast to cation yields which also exhibit pronounced structure due to the well-known σ^* shape resonance. Because the shape resonance is completely suppressed for O^-, anion spectroscopy thus constitutes a highly selective probe, yielding information unobtainable with absorption or electron spectroscopy.

Trimethylsulfonium Methanesulfonate, Frank R. Fronczek, Rolanda J. Johnson, Robert M. Strongin

Chemistry Faculty Publications and Presentations

In the title compound, C₃H₉S⁺.CH₃O₃S^-, a thermal decomposition product of dimethyl sulfoxide, both cation and anion lie on mirror planes. In the cation, the S atom lies 0.792 (2) Å out of the plane defined by the three C atoms, with S-C distances of 1.781 (2) and 1.786 (3) Å. In the anion, the S-O distances are 1.4556 (14) and 1.4646 (19) Å, and the S-C distance is 1.759 (3) Å.

PkA Determination Of Enzyme Bound Coenzyme M With Epoxyalkane: Com Transferase, Matthew Stephen Mciff

Undergraduate Honors Capstone Projects

Epoxide metabolism in the aerobic bacterium Xanthobacter strain Py2 proceeds by a coenzyme M (2-mercaptoethanesulfonic acid), NADPH, and NAD⁺ dependent carboxylation reaction that form beta keto acids as products. Epoxide carboxylase, the enzyme catalyzing this reaction, was resolved into four protein components that are required for functional reconstitiution of epoxide carboxylase activity. Component I, the first step in epoxide carboxylation, catalyzes the conversion of R and S-epoxypropane into Rand S-hydroxypropyl-coenzyme M respectively. This reaction consists of an epoxide ring opening, nucleophilic addition of coenzyme M, and oxygen reduction. Coenzyme M, a compound previously found only in the methanogenic Archaea, …

New Approaches To Processing Nanoparticles And Nanostructures, Mathew M. Maye

Undergraduate Honors Theses

The study of nanoparticles is an emerging field of nanoscience and nanotechnology. A challenging issue is how deliberate tailoring and processing of the nanoscale materials can lead to well defined and functional nanostructures. In this thesis, we explore new strategies of nanoscale design and processing to address the challenge.

A core-shell chemical processing route towards fabrication of functional composite nanomaterials with defined sizes, shapes, compositions and surface properties is demonstrated. New findings of an investigation of thermally-activated core-shell reactivities of nanoparticles in solutions are described. Gold nanoparticles of ~2-nm core size with thiolate monolayer encapsulation were chosen as a model …

Energy Gaps In “Metallic” Single-Walled Carbon Nanotubes, Min Ouyang, Jin-Lin Huang, Chin Li Cheung, Charles Lieber

Barry Chin Li Cheung Publications

Metallic single-walled carbon nanotubes have been proposed to be good one-dimensional conductors. However, the finite curvature of the graphene sheet that forms the nanotubes and the broken symmetry due to the local environment may modify their electronic properties. We used low-temperature atomically resolved scanning tunneling microscopy to investigate zigzag and armchair nanotubes, both thought to be metallic. “Metallic” zigzag nanotubes were found to have energy gaps with magnitudes that depend inversely on the square of the tube radius, whereas isolated armchair tubes do not have energy gaps. Additionally, armchair nanotubes packed in bundles have pseudogaps, which exhibit an inverse dependence …

A Greek Cross Dodecaphenylene: Sparteine-Mediated Asymmetric Synthesis Of Chiral D2-Symmetric Π-Conjugated Tetra-O-Phenylenes, Andrzej Rajca, Hua Wang, Pavel Bolshov, Suchada Rajca

Andrzej Rajca Publications

The asymmetric synthesis of a chiral, nonracemic π-conjugated system with D₂ point group of symmetry, dodecaphenylene 4 is described. In the key step, (−)-sparteine- and Cu(II)-mediated oxidation of 2,2′-dilithio-1,1′-biaryls in ether gives the corresponding dimers, tetra-o-phenylenes, in 80% isolated yields and 50–60% ee’s. X-Ray crystallography confirms the structure of rac-4 and its molecular shape of a Greek cross. The torsional angles between the benzene rings in the tetra-o-phenylene core of rac-4 are in the 56.5–71.0° range. However, CD and UV spectra of 4 in CH₂Cl₂ are consistent with significant conjugation between the …

Dependence Of 13C Nmr Chemical Shifts On Conformations Of Rna Nucleosides And Nucleotides, Mohsen Ebrahimi, Paolo Rossi, Christopher Rogers, Gerard S. Harbison

Gerard S. Harbison Publications

Cross-polarization magic-angle spinning solid-state NMR spectroscopy has been used to investigate the dependence of ¹³C sugar chemical shifts on specific conformational parameters of a variety of ribonucleotides and ribonucleosides. Solid-state NMR is a valuable tool for nucleoside and nucleotide structural studies since it provides the means to acquire spectra that correspond to single conformations, as opposed to ¹³C solutionNMRmethods. The distinct effects of sugar puckering on the C1′, C4′, and C5′ resonances of C2′ endo (S type) and C3′ endo (N type) furanoid conformations allow us to separate them into two groups. Further analysis of each group reveals …

Determination Of Lysophosphatidic Acids By Capillary Electrophoresis With Indirect Ultraviolet Detection, Yi Lung Chen, Yan Xu

Chemistry Faculty Publications

Lysophosphatidic acid (LPA) is the simplest form of lysophospholipid. Molecular species of LPA have been identified as the potent components in the ovarian cancer activation factor. The elevated plasma LPAs may be used as potential biomarkers for the early detection of ovarian cancer. This paper is the first report on the quantitative analysis of molecular species of LPA using capillary electrophoresis. In this work, the separation of LPAs was achieved within 14 min in an adenosine monophosphate-borate–methanol–water solution, and the measurement was accomplished by indirect UV detection. With LPA (D) as internal standard, the method had linear calibration ranges for …

Observations On Lemon Cells, Jerry Goodisman

Chemistry - All Scholarship

In many general chemistry texts (1), the electrochemistry chapter is introduced with a picture of a “lemon cell”, leads of Zn and Cu piercing a lemon (or sometimes a grapefruit). A voltmeter connected across them shows a potential of about 1 V. (It has been shown how several fruits connected in series can be used to run a calculator [2].) The texts then discuss oxidation–reduction, half-cells, and the rest of what we teach freshmen about electrochemistry, and the lemon is never mentioned again.

It would appear to be questionable scientific pedagogy to present something, even something …

Ua66/7/2 Hilltopper News, Wku Chemistry

WKU Administration Documents

Newsletter created by and about the WKU Chemistry department.

Infrared Spectroscopy Of H-Bonded Bridges Stretched Across The Cis-Amide Group: I. Water Bridges, Joel R. Carney, A. V. Fedorov, John R. Cable, Timothy S. Zwier

Chemistry Faculty Publications

The water-containing clusters of oxindole (OI) and 3,4-dihydro-2(1H)-quinolinone (DQ) have been studied in the hydride stretch region of the infrared by the technique of resonant ion-dip infrared spectroscopy (RIDIRS). Both OI and DQ are constrained cis-amides with adjacent N-H and C=O groups between which water can form H-bonded bridges. The hydride stretch fundamentals of OI-W-n with n = 1-3 and DQ-W-n with n = 1, 2 without exception divide up into free OH stretch fundamentals near 3700 cm(-1) and a set of H-bonded bridge fundamentals in the 3200-3450 cm(-1) region. The bridge fundamentals show a distribution of intensities that reflects …