Chemistry Commons^™

Electrochemical Synthesis Of Hierarchical Dendritic Polyaniline Nanostructures, Shao-Huang Weng, Jian-Zhang Zhou, Zhong-Hua Lin, Xin-Hua Lin

Journal of Electrochemistry

In this work, the p-TSA doped and hierarchical dendritic nanostructured polyanilines (PANI) have been prepared by potentiostatic electropolymerization without using any templates at room temperature. The mechanism of the polymerization has been discussed according to the electrodeposition curves. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to confirm the formation of uniform hierarchical dendritic structure on PANI. UV-Vis spectroscopy (UV-Vis) and infrared spectroscopy (FTIR) proved that the prepared PANI is in the form of emeraldine salt. The templateless electrodeposition method is simple, easy to operate, can be applied to fabricate other nanostructures of conducting polymers.

Performance Of Vn As Negative Electrode Materials In Electrochemical Capacitors, Zhao-Hui Gao, Hao Zhang, Gao-Ping Cao, Min-Fang Han, Yu-Sheng Yang

Journal of Electrochemistry

Nanocrystalline vanadium nitride (VN) materials were synthesized by high temperature ammonia (NH₃) reduction of vanadium oxide (V₂O₅). The structure and morphology of VN materials were characterized by XRD, SEM and TEM, while the specific surface area, pore size distribution and supercapacitive behavior by N₂ absorption, cyclic voltammetry (CV) and constant current charge-discharge measurements in 1 mol·L-1 KOH electrolyte. The results showed that the VN sample belonged to the cubic crystal system (Fm3m [225]), and had homogeneous surface and appeared nearly spherical with uniform size. As the reaction time was extended to 12 h, …

Electrochemical Performance Of Lifepo4/C Synthesized Via Aqueous Solution-Evaporation Route, Ning-Yu Gu, Xing-Hua He, Yang Li

Journal of Electrochemistry

The LiFePO₄/C samples have been synthesized via an aqueous solution-evaporation route with LiH₂PO₄, FeC₂O₄.2H₂O as raw materials and citric acid as a carbon source. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to analyze structure and morphology of the samples. The electrochemical performances of the LiFePO₄/C cathodes were characterized by charge/discharge cures and electrochemical impedance spectroscopy (EIS). The results show that the LiFePO₄/C sample, calcined at 700 °C and contained 3.03% (by mass) carbon, exhibited a highly pure …

Preparation And Methanol Electrooxidation Of Pt/Pmo12/Pedot/Gc Electrodes, Jing-Hua Ma, Rui-Xiang Wang, Yi-Liang Tan, Shan-Shan Wang, Yan-Qin Zhang, You-Jun Fan

Journal of Electrochemistry

Modification of phosphomolybdic acid (PMo₁₂) on poly(3,4-ethylenedioxythiophene) (PEDOT) film (PEDOT/GC) obtained through the electrochemical polymerization was performed using adsorption method (PMo₁₂/PEDOT/GC), followed by electrodepositing Pt on PMo₁₂/PEDOT/GC to prepare Pt/PMo₁₂/PEDOT/GC electrode. Effects of PMo₁₂ and PEDOT on the methanol oxidation performance of electrode were investigated. Results showed that PMo₁₂ obviously changed the morphology and structure of Pt loaded on the electrode, leading to the formation of sharp thorns at the edge of Pt nanostructures. Cyclic voltammetry and chronoamperometry data demonstrated that the catalytic activities of methanol electrooxidation on the Pt/PMo …

The Electrochemical Capacitance Performance Of La1-XSrXCoo3 Perovskites, Yang Xu, Yan-Yan Bao, Long-Fei Du, Dian-Xue Cao, Gui-Ling Wang

Journal of Electrochemistry

In this paper, the La_1-xSr_xCoO₃ (x = 0.2, 0.4, 0.6, 0.8) perovskites powders were synthesized by a sol-gel method. The perovskite phases were characterized by X-ray diffraction (XRD), while the electrochemical capacitance performance of La_1-xSr_xCoO₃ electrodes in alkaline electrolyte was studied by cyclic voltammetry and galvanostatic charge/discharge test. It was found that the La_0.6Sr_0.4CoO₃ electrode exhibited a specific capacitance of 325 F.g^-1 in 6.0 mol.L^-1 KOH electrolyte at a current density of 10 mA.cm^-2, and the specific capacitance of 315 F.g …

Synthesis And Electrochemical Performance Of Si/C Composite Modified By Pani, Guang-Hui Zhang, Pei-Kang Shen, Ge Sang, Ren-Jin Xiong

Journal of Electrochemistry

Silicon/carbon (Si/C) composite materials were prepared through high-energy ball milling and high-temperature solid-phase method, and then coated with thin polyaniline (PAni) film by oxidation. The microstructure and component of the composites were characterized by SEM, XRD, IR, TG, and the electrochemical performance was investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge tests. The results showed that the surface of PAni/Si/G/C composite was coating with complete lamellar structure of PAni film. Its reversible capacity was 784 mAh·g^-1 and 690 mAh·g^-1 could be maintained after 50th charge-discharge cycles.

Synthesis Of Lifepo4/C Cathode By Sol-Gel And Calcining Method With Chitosan Monomer, Jia Xu, Yan-Yan Wang, Rui Wang, Bo Wang, Yue Pan, Dian-Xue Cao, Gui-Ling Wang

Journal of Electrochemistry

The LiFePO₄/C cathode materials for Li-ion battery were synthesized by sol-gel and calcining method using chitosan monomer as a carbon source and a gelating agent. The structures and morphologies were characterized by X-ray diffraction spectroscopy (XRD) and scanning electron microscopy (SEM). The electrochemical performance was investigated by the galvanostatic charge–discharge test. When the molar ratios between chitosan monomer and LiFePO₄ were 1:1.2, the LiFePO₄/C cathode calcined at 600 ^oC showed the best performance. The particle sizes ranged 200 ～ 400 nm. The initial discharge capacity of 155 mAh·g-¹ was achieved at room temperature …

Current Development Of Quantum Dots Based Electrochemiluminescence Immunosensors, Ling-Ling Li, Qian Lu, Jun-Jie Zhu

Journal of Electrochemistry

Electrochemiluminescence exhibits the merits of both luminescence and electrochemistry analysis, and has been extensively employed in biosensors. Quantum dots are considered one of the three main kinds of electrochemiluminescence luminophores due to their unique properties. This paper briefly reviews the classification and signal amplification technology of quantum dots based electrochemiluminescence immunosensors. Future research trends are also suggested.

Synthesis And Electrocatalysis Of Pdcu Alloy Nanocrystals, Hai-Bin Wu, Rui-Zhong Zhang, Wei Chen

Journal of Electrochemistry

Monodispersed PdCu alloy nanoparticles were synthesized by co-reduction of Cu(acac)2 and Pd(acac)2 with 1, 2-hexadecanediol. The spherical and popcorn-like shapes of PdCu alloy nanoparticles were obtained by changing the ratios of mixed surface protecting ligands of 1-octadecene, and oleylamine or oleic acid. TEM and XRD measurements showed that both PdCu nanoparticles are alloy nanocrystals dominated with (111) planes and the average sizes are 12.7 ± 0.18 and 20.4 ± 0.31 nm for he spherical and popcorn-like PdCu nanoparticles, respectively. The electrocatalytic activities of the PdCu nanocrystals for formic acid oxidation were evaluated by electrochemical cyclic voltammetry (CV). The result showed …

Properties Of Carbon Coated Tin Negative Electrode For Lithium-Ion Battery, Gui-Chang Liu, Xiao-Xiao Shen, Li-Da Wang

Journal of Electrochemistry

Carbon coated tin power was prepared by decomposing glucose applying a hydrothermal method, and was further used as the active material for negative electrode of lithium secondary battery. Charge-discharge tests show that the carbon coated tin electrode with the addition of 5 wt.% acetylene black as a conductive agent could obtain an initial discharge capacity of 967 mAh·g^-1 and a discharge capacity of 362 mAh·g^-1 after 50 cycles, which is much higher than that of tin electrode (166 mAh·g^-1 after 50 cycles). The coated carbon hinders the agglomeration of tin powder, reduces the irreversible capacity loss of …

Molecular Design And Photophysical Characterization Of Synthetic Bacteriochlorins For Solar Energy Conversion And Photodynamic Therapy, Eunkyung Yang

All Theses and Dissertations (ETDs)

The design, photophysical characteristics and some potential applications of synthetic bacteriochlorins are discussed. Bacteriochlorins: e.g., bacteriochlorophylls) are tetrapyrrole macrocycles with two reduced pyrrole rings, whereas chlorins: e.g., chlorophylls) and porphyrins: e.g., hemes) have one and zero reduced pyrrole rings. Molecular design characteristics are revealed by understanding the effects of substituent types and patterns and the central metal ion on the photophysical properties and electronic structure. These effects are elucidated via studies of the optical absorption and emission spectra and excited-state decay pathways, and analysis of the molecular-orbital characteristics within the four-orbital model. The studies also encompass analysis of the properties …

Molecular Hospitality: An Examination Of The Interactions Between Brooker’S Merocyanine And Modified Cyclodextrins, Benjamin Averill

Symposium on Research and Creative Expression (SORCE)

The equilibrium of a guest molecule binding to a host occurs through weak molecular interactions instead of through the formation of chemical bonds. A cyclodextrin (CD) is used as the host molecule due to its basket-like shape which is beneficial to complex formation with the guest molecule, Brooker’s merocyanine (BM), which fits well within beta-CD. BM is a highly conjugated dye that can exhibit a charge, allowing for a variety of the weak molecular interactions involved with complex formation, such as hydrogen bonds, to be studied. This project focuses on the effect of different modifications to the CD on the …

Searching For A New Epoxide Precursor In Tmm Cycloaddition Reactions, Christopher Miko

Symposium on Research and Creative Expression (SORCE)

In order to explore the feasibility of Pd(0)-catalyzed trimethylenemethane (TMM) cycloaddition reactions with epoxides, the precursor trimethyl-(2-oxiranyl-2-propenyl)-silane (1) was synthesized in a three-step process from propargyl alcohol and reacted with dimethyl malonate, with Pd(PPh3)4 acting as a catalyst, in both THF and toluene. This reaction was performed to examine whether the π-allyl Palladium complex forms and whether the epoxide ring opens. NMR spectra show support for π-allyl Palladium complex formation, the epoxide ring opening, and the presence of the expected product, although the solvent used may affect which product forms. Efforts to characterize the product(s) are ongoing.

Investigations Of The Application Of Black Carbon For The Retention And Stabilization Of Nonylphenol In Soil, Kelly Belisle, Laura Mattson, Caitlin Soley

Symposium on Research and Creative Expression (SORCE)

We used black carbon (BC) to absorb and stabilize nonylphenol (NP) that was present in soil samples. BC is an efficient material for absorbing and stabilizing hydrophobic organic compounds because this material has a high absorption capacity and strongly binds organic molecules. Thus, black carbon has the ability to retain NP in the soil minimizing loss to runoff while providing microbes with longer times (up to several hundred years) to metabolize the NP to less hazardous compounds. NP is both an endocrine-disrupter and a toxic pollutant. It also serves as a model compound for the study of stabilization of organic …

Water Quality Monitoring Of The Little Calumet East Branch Watershed, Nicholas H. Feller, Melissa Dorton

Symposium on Research and Creative Expression (SORCE)

The Little Calumet East Branch (LCEB) is a 10-digit hydrologic unit code (HUC) watershed that ultimately discharges into Lake Michigan. The watershed begins in unincorporated LaPorte County and discharges west through unincorporated Porter County, converges with the West Branch of the Little Calumet River, and finally discharges into Lake Michigan via the Burns Ditch Waterway. A water quality monitoring study was performed in the summer of 2012 as part of the watershed management process led by a not-for-profit organization, Save the Dunes. Save the Dunes’ Great Lakes Innovative Stewardship through Education Network (GLISTEN) liaisons initiated weekly monitoring at eleven LCEB …

Release Of Phosphorus From Sediment Into Pore Water, Adam Dickey, Wang Hang, Dr. Zhang Zhijian

Symposium on Research and Creative Expression (SORCE)

As global climate change becomes an increasing problem, it is important to understand the effects that it may cause. One possible set of effects are changes in solubility of various pollutants in aqueous systems. Phosphorus (P) and nitrogen are two important nutrients that become pollutants when present at elevated concentrations. Phosphorus is particularly worrisome because it is generally the nutrient that limits plant growth. It also binds to particles and is difficult to eliminate from aqueous systems. In collaboration with researchers at Zhejiang University, we determined the total amount of phosphorus released from six different types of wetland sediment into …

Mesobiliverdin Ixα Enhances Rat Pancreatic Islet Yield And Function, Taihei Ito, Dong Chen, Cheng-Wei Tom Chang, Takashi Kenmochi, Tomonori Saito, Satoshi Suzuki, Jon Y. Takemoto

Chemistry and Biochemistry Faculty Publications

The aims of this study were to produce mesobiliverdin IXα, an analog of anti-inflammatory biliverdin IXα, and to test its ability to enhance rat pancreatic islet yield for allograft transplantation into diabetic recipients. Mesobiliverdin IXα was synthesized from phycocyanobilin derived from cyanobacteria, and its identity and purity were analyzed by chromatographic and spectroscopic methods. Mesobiliverdin IXα was a substrate for human NADPH biliverdin reductase. Excised Lewis rat pancreata infused with mesobiliverdin IXα and biliverdin IXα-HCl (1–100 μM) yielded islet equivalents as high as 86.7 and 36.5%, respectively, above those from non-treated controls, and the islets showed a high degree of …

Method Of Ameliorating Oxidative Stress And Supplementing The Diet, Boyd E. Haley, Niladrl Narayan Gupta

Chemistry Faculty Patents

A method of supplementing a diet and ameliorating oxidative stress in a mammal includes administering a pharmaceutically effective amount of lipid soluble, hydrophobic active compounds having a chemical structure . . .

To see the remainder of this abstract, please download this patent.

Supramolecular Composite Materials From Cellulose, Chitosan, And Cyclodextrin: Facile Preparation And Their Selective Inclusion Complex Formation With Endocrine Disruptors, Simon Duri, Chieu D. Tran

Chemistry Faculty Research and Publications

We have successfully developed a simple one-step method of preparing high-performance supramolecular polysaccharide composites from cellulose (CEL), chitosan (CS), and (2,3,6-tri-O-acetyl)-α-, β-, and γ-cyclodextrin (α-, β-, and γ-TCD). In this method, [BMIm⁺Cl^–], an ionic liquid (IL), was used as a solvent to dissolve and prepare the composites. Because a majority (>88%) of the IL used was recovered for reuse, the method is recyclable. XRD, FT-IR, NIR, and SEM were used to monitor the dissolution process and to confirm that the polysaccharides were regenerated without any chemical modifications. It was found that unique properties …

Reliable Peak Selection For Multisample Analysis With Comprehensive Two-Dimensional Chromatography, Stephen E. Reichenbach, Xue Tian, Akwasi A. Boateng, Charles A. Mullen, Chiara Cordero, Qingping Tao

School of Computing: Faculty Publications

Comprehensive two-dimensional chromatography is a powerful technology for analyzing the patterns of constituent compounds in complex samples, but matching chromatographic features for comparative analysis across large sample sets is difficult. Various methods have been described for pairwise peak matching between two chromatograms, but the peaks indicated by these pairwise matches commonly are incomplete or inconsistent across many chromatograms. This paper describes a new, automated method for postprocessing the results of pairwise peak matching to address incomplete and inconsistent peak matches and thereby select chromatographic peaks that reliably correspond across many chromatograms. Reliably corresponding peaks can be used both for directly …

Development And Characterization Of Multi-Functional Probes For Use With Scanning Electrochemical Microscopy, Jiwon Lee, Colleen Leonard, Melinda Baur, Faculty Advisor

John Wesley Powell Student Research Conference

Using Scanning Electrochemical Microscopy (SECM) with electrode probes that make simultaneous current and impedance measurements is useful for analysis of biological substrates. The current and impedance measurements are both dependent upon the proximity to a surface.

Experiments with the single carbon fiber electrodes show that the impedance measurements are independent of the current and applied potential. In order to detect neurotransmitter release from a cell, the electrode must be positioned very close to the cell surface. Impedance-based positioning eliminates the need for addition of biologically toxic redox mediators to position the electrode. Furthermore, it was found that multiple carbon fiber …

A Combined Radio- And Stable-Isotopic Study Of A California Coastal Aquifer System, Peter W. Swarzenski, Mark Baskaran, Robert J. Rosenbauer, Brian D. Edwards, Michael Land

Environmental Science and Geology Faculty Research Publications

Stable and radioactive tracers were utilized in concert to characterize geochemical processes in a complex coastal groundwater system and to provide constraints on the kinetics of rock/water interactions. Groundwater samples from wells within the Dominguez Gap region of Los Angeles County, California were analyzed for a suite of major cations (Na⁺, K⁺, Mg²⁺, Ca²⁺) and anions (Cl⁻, SO₄²⁻), silica, alkalinity, select trace elements (Ba, B, Sr), dissolved oxygen, stable isotopes of hydrogen (δD), oxygen (δ¹⁸O), dissolved inorganic carbon (δ¹³C_DIC), and radioactive …

Kinetics Of Atmospheric Reactions Of Biogenic Volatile Organic Compounds: Measurement Of The Rate Constant Ofthujone + Cl· At 296 K And Calculation Ofthe Equilibrium Constant For The Ho2ch2ch2o2· H2o Complex, Marie Coy Killian

Theses and Dissertations

Biogenic volatile organic compounds (VOCs) react with Cl and OH radicals and the resulting radicals combine with oxygen to form peroxy radicals RO2. Organic peroxy radicals can then react with NO to form NO2, a precursor of tropospheric ozone. The work presented here explored the initial reaction between Cl and thujone, a VOC emitted by Great Basin sagebrush. The rate constant for the reaction of thujone + Cl at 296 K was measured with the method of relative rates with FTIR for detection of reactants. LEDs were used to photolyze Cl2 to generate Cl in the reaction cell. Thujone was …

Four Named To Endowed Professorships, Kim Hill

News and Events (Discontinued Series)

No abstract provided.

Formation Mechanisms And Photocatalytic Properties Of Zno-Based Nanomaterials, Natalie Herring

Theses and Dissertations

Zinc Oxide (ZnO) is one of the most extensively studied semiconductors because of its unique properties, namely, its wide band gap (3.37 eV) and high excitation binding energy (60 meV). These properties make ZnO a promising material for uses in a broad range of applications including sensors, catalysis and optoelectronic devices. The presented research covers a broad spectrum of these interesting nanomaterials, from their synthesis and characterization to their use as photocatalyts. A new synthetic approach for producing morphology controlled ZnO nanostructures was developed using microwave irradiation (MWI). The rapid decomposition of zinc acetate in the presence of a mixture …

Synthesis And Functionalization Of Small Silver Nanoparticles, Chris Menter, Jeunghoon Lee, Sarah Rhen, Elton Graugnard, Bernard Yurke, William Knowlton, Will Hughes, Wan Kuang

College of Arts and Sciences Poster Presentations

Metal nanoparticles in general exhibit interesting properties due to their small sizes. This response shows up as an intense absorption band in the visible region making metallic nanoparticles ideal probes for medical imaging as well as for countless other applications. Functionalizing metallic nanoparticles with DNA enables targeted labeling, controlled by their base sequence. Another purpose of functionalization is to attach the nanoparticle to a DNA substrate allowing controlled bottom up engineering of nanoscale devices. Gold or gold-encapsulated silver is usually used for these purposes instead of bare silver due to the ease with which silver is oxidized although silver nanoparticles …

Protein-Protein Interaction Between Multi-Functional Protein Cad And Protein Phosphastase 1 (Pp1), Meenal Mhaskar

Master's Theses and Doctoral Dissertations

Uncontrolled cell proliferation, a hallmark of cancer, is associated with activation of CAD, a multifunctional protein that catalyzes the first three steps in pyrimidine biosynthesis. The cell cycle dependent regulation of pyrimidine biosynthesis is a consequence of sequential phosphorylation of CAD Thr-456 and Ser-1406 by the MAP kinase and PKA cascades, respectively. The mechanism that controls the timing of these events is not well understood. Our hypothesis is that timing of the activation and nucleocytoplasmic dynamics of CAD is controlled by signaling complexes with kinases and phosphatases. Interestingly, a consensus sequence for PP1 targeting proteins is located immediately adjacent to …

Graphene-Based Semiconductor And Metallic Nanostructured Materials, Abdallah Zedan

Theses and Dissertations

Exciting periods of scientific research are often associated with discoveries of novel materials. Such period was brought about by the successful preparation of graphene which is a 2D allotrope of carbon with remarkable electronic, optical and mechanical properties. Functional graphene-based nanocomposites have great promise for applications in various fields such as energy conversion, opteoelectronics, solar cells, sensing, catalysis and biomedicine. Herein, microwave and laser-assisted synthetic approaches were developed for decorating graphene with various semiconductor, metallic or magnetic nanostructures of controlled size and shape. We developed a scalable microwave irradiation method for the synthesis of graphene decorated with CdSe nanocrystals of …

Large-Scale Structural Rearrangement Of A Serine Hydrolase From Francisella Tularensis Facilitates Catalysis, Ekaterina V. Filippova, Leigh A. Watson, Misty L. Kuhn, Brett Geissler, Daniel Becker

Chemistry: Faculty Publications and Other Works

Tularemia is a deadly, febrile disease caused by infection by the gram-negative bacterium, Francisella tularensis. Members of the ubiquitous serine hydrolase protein family are among current targets to treat diverse bacterial infections. Herein we present a structural and functional study of a novel bacterial carboxylesterase (FTT258) from F. tularensis, a homologue of human acyl protein thioesterase (hAPT1). The structure of FTT258 has been determined in multiple forms, and unexpectedly large conformational changes of a peripheral flexible loop occur in the presence of a mechanistic cyclobutanone ligand. The concomitant changes in this hydrophobic loop and the newly exposed hydrophobic substrate binding …

Supramolecular Chemistry For Students, Dr. Roger Harrison, Dr. John Lamb, Dr. David Dearden

Journal of Undergraduate Research

Students working in the mentoring environment synthesized compounds and worked with separation and mass analyzer instruments. They learned how to make new compounds by organic synthesis and characterize their compounds by NMR and mass spectrometry. They also had the opportunity to work with other students who were working to apply their new compounds to chemical separations. They applied reactions they had learned in their courses. They learned to solve problems by finding new ways to synthesize or characterize their compounds. They learned to run, fix, and change settings on multifaceted instruments. They learned to trouble-shoot problems to solve instrumental errors. …