Physical Chemistry Commons^™

Electrochemical Treatment Of Heavy Metals With Self-Electricity Generation, Wei Xu, Hui-Min Zhang, Zu-Cheng Wu

Journal of Electrochemistry

Heavy metal pollution is among the most serious environmental problems. Electrochemical method possesses many advantages like speediness and high efficiency, which develops rapidly. This review describes the aspect and application of heavy metals with self-electricity generation according to the primary batteries and fuel cells. Some examples to reduce heavy metal ions in the cathode are introduced. Applicability of this technology for removing heavy metals is also discussed. Employing electrochemical technology to treat contaminants with self-energy generation instead of exhausting energy will have a good prospect.

Electrochemical Behavior And Content Determination Of Paeonol At Poly Sudan Ⅲ Modified Electrode, Yan-Jie Zheng, Ai-Lin Liu, Yun Lei, Xin-Hua Lin

Journal of Electrochemistry

The poly SudanⅢ modified electrode was characterized by electrochemical impedance spectroscopy（EIS）and cyclic voltammetry (CV), while the electrochemical behavior of paeonol was studied by cyclic voltammetry (CV). The result shows that the poly Sudan Ⅲ modified electrode exhibits excellent electrocatalytic effect on the oxidation of paeonol. The peak currents of differential pulse voltammetry are linear to the paeonol concentrations over the range of 3.0*10^-7 ~ 2.2*10^-5 mol·L^-1. The detection limit has been estimated to be 5.0*10^-8 mol·L^-1. This method can be used for determination of paeonol content in real sample with satisfactory results.

Io3- And I- Sorption From Groundwater By Layered Double Hydroxides, Abbey Rickelmann, Emily Campbell, Natasha Pence, Tatiana Levitskaia, Sayandev Chatterjee, Frances Smith

STAR Program Research Presentations

Several subsurface water plumes are found at the Hanford U.S. DOE site. These plumes contain many different types of hazardous components including radioactive iodate (IO₃^-) and iodide (I^-), which may have deleterious health effects. To selectively uptake IO₃^- and I^-, inorganic layered double hydroxide (LDH) compounds were synthesized and tested. LDHs are mixed transition metal hydroxides that contain positively charged layers that undergo anion exchange. When LDHs are submerged in the plume water, they can selectively uptake IO₃^- and I^- and remove them from the plume. Raman spectroscopy …

Synthesis And Computational Studies Of A New Class Of Lanthanide Niobate Cluster : [Ln4(H2O)8(So4)5(Nbo3)2]+3h2O; Ln= Dy, Tb, Brady D. Garabato

Masters Theses & Specialist Projects

Polyoxoniobates (PONbs) are a small family of highly electron-rich clusters. The development of new solids composed of these clusters have applications in green energy and electronics. However, the high charge environment of PONbs typically requires alkaline synthetic conditions that are unsuitable for introducing other metals and organic molecules, making synthesis of new systems difficult. To date, very few transition metals and organic ligands have been incorporated into these PONb solids, and lanthanide metal inclusion, which generally improves photoconductivity due to longlived f-orbital excitations, has not yet been fully realized. Here, the synthesis of a new class of lanthanide niobate cluster …

Fabrication Of Tungsten Tips Suitable For Scanning Probe Microscopy By Electrochemical Etching Methods, Gobind Basnet

Graduate Theses and Dissertations

The fabrication of metal tips is becoming an interesting field for scientists who are working in spectroscopy measurements. A significant amount of work has already been done in the tips fabrication process. Metal tips used to analyze the surface of materials play a key role in the scanning tunneling microscope (STM) technique. It's remarkable quality that it is used to study the surface of material at the atomic level.

There are various methods used in the tips fabrication process. Of diverse methods, three different electrochemical etching methods: submerged method, single lamella drop-off method, and double lamella drop-off method are commonly …

The Magnesium Isotopologues Of Mgh In The A2Π-X 2Σ+ System, Kenneth H. Hinkle, Lloyd Wallace, Ram S. Ram, Peter F. Bernath, Christopher Sneden, Sara Lucatello

Chemistry & Biochemistry Faculty Publications

Using laboratory hollow cathode spectra we have identified lines of the less common magnesium isotopologues of MgH, ²⁵MgH and ²⁶MgH, in the A²Π-X²Σ⁺ system. Based on the previous analysis of ²⁴MgH, molecular lines have been measured and molecular constants derived for ²⁵MgH and ²⁶MgH. Term values and linelists, in both wavenumber and wavelength units, are presented. The A²Π-X²Σ⁺ system of MgH is important for measuring the magnesium isotope ratios in stars. Examples of analysis using the new linelists to derive the Mg isotope ratio in …

Modeling Chemical Reactions In Aqueous Solutions, Osman Uner

Graduate Theses and Dissertations

The energy barriers for SN2 ligand exchange reactions between the chloride anion and para-substituted benzyl chlorides were investigated both in water solution and in the gas phase by using quantum chemical simulations at the DFT and Hartree-Fock levels. The question addressed was the effect of the solvent (water) and of the substituent on the barrier height. The para substitutient groups included NH2, OH, OCH3, CH3, C(CH3)3, H, F, Cl, Br, I, CF3, CN, NO2, and SO3- . The calculations in aqueous solution were carried out with the recently developed Ultrafast Monte Carlo method using the TIP3P explicit water model. The …

Optimization Of Sample Preparation In Matrix-Assisted Laser Desorption/Ionization (Maldi) Mass Spectrometry Of Macromolecules, Evgenia Akhmetova

Graduate Theses and Dissertations

New method for the matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and Fourier transform mass spectrometry (MALDI-FTMS) analysis of low molecular weight polyvinyl acetate (PVAc) was developed and then applied to the characterization of commercially available chewing gum. The optimization of MALDI analysis of PVAc was achieved by investigating the influence of sample preparation variables such as the choice of solvent and choice of matrix-analyte ratio. It was demonstrated that the use of ethyl acetate as a solvent and 2,5-Dihydroxybenzoic acid as a matrix yielded the highest signal intensity for the pure polymer sample. The application of TOF technique did not …

Spectroscopic And Computational Electronic Structure Studies Of Donor-Acceptor Systems, Diana Habel-Rodriguez

Chemistry and Chemical Biology ETDs

Three molecular systems have been studied, which exhibit strong intramolecular electronic communication between constituent moieties. Experimental results for electronic absorption, resonance Raman, electron paramagnetic resonance (EPR), and magnetic circular dichroism (MCD) spectroscopies are presented. Density functional theory (DFT) electronic structure calculations were employed to augment the interpretation of experimental results. Using a valence bond configuration interaction (VBCI) model we show that the ground state properties of the molecules are influenced by excited state configurations. Donor ( = semiquinone)-bridge-acceptor ( = nitronylnitroxide) biradicals show strong ferromagnetic donor-acceptor coupling, and contributions to the ferromagnetic coupling from spin delocalization and spin polarization mechanisms …

Catalytic Mechanism And Function Evolvement Studies Of Phosphatases Within Haloacid Dehalogenase Superfamily (Hadsf), Li Zheng

Chemistry and Chemical Biology ETDs

The haloacid dehalogenase superfamily (HADSF) is one of the largest known enzyme superfamilies, having more than 32,000 nonredundant members. Enzymes in this superfamily catalyze a number of different chemical reactions including dehalogenation, phosphoryl transfer, and hydrolysis of phosphate esters and phosphates. The vast majority of HADSF members are phosphatases, which contain a highly conserved core domain that is constructed to catalyze hydrolysis reactions of phosphorylated sugars or nucleotides by using an active site Asp nucleophile and a Mg²⁺ cofactor. Most phosphatases possess a cap domain, which in association with the core domain assists active site desolvation and binds the …

Exploration Of Aqueous Interfaces And Their Effect On Ion Behavior, Oneka T. Cummings

Doctoral Dissertations

An in-depth understanding of a wide range of physical, chemical, atmospheric and biological processes can only be achieved after the structure and dynamics of interfaces and the interfacial behavior of aqueous species, such as ions, are thoroughly studied and understood. This dissertation describes computational studies conducted to gain a more comprehensive understanding of such interfaces and the behavior of ions in the bulk and interfacial regions of the (1) air/water interface, and (2) alkane/water interfaces.

At the air/water interface the effect of counterion (sodium cations) charge and the influence of ion pairing on anion (chloride) propensity for the air/water interface …

Characterization By Nmr Of Reactants And Products Of Hydrofluoroether Isomers, Cf3(Cf2)3och3 And (Cf3)2c(F)Cf2och3, Reacting With Isopropyl Alcohol, Howard Knachel, Vladimir Benin, William E. Moddeman, Janine C. Birkbeck, Thomas A. Kestner, Tayna L. Young

Chemistry Faculty Publications

The 3M Company product Novec™ 71IPA DL, a mixture of methoxyperfluorobutane, methoxyperfluoroisobutane and 4.5 wt.% isopropyl alcohol, has been found to be very stable at ambient temperature, producing fluoride at the rate of ~1 ppm/year. Our earlier kinetic and theoretical studies have identified the reaction mechanism. This paper identifies the ¹H and ¹⁹F NMR chemical shifts, multiplicities, and coupling constants of reactants and the major products that result from aging the mixture in sealed Pyrex NMR tubes for periods up to 1.8 years at temperatures from 26 °C to 102 °C. Chemical shifts and coupling constants of fluorine …

Effect Of Ethyl Propionate On Low-Temperature Performance Of Lifepo4-Based Li-Ion Battery, Xiao-Ping Li, Lian-Sheng Hao, Wei-Shan Li, Meng-Qing Xu, Li-Dan Xing

Journal of Electrochemistry

A linear carboxylic, ester ethyl propionate (EP), was used as the co-solvent of carbonates, ethylene carbonate (EC), ethyl-methyl carbonate (EMC) and dimethyl carbonate (DMC), and its effect on low-temperature performance of LiFePO₄-based Li-ion battery was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge test. The application of EP enhances the ionic conductivity of the electrolyte, improves the compatibility of the electrolyte with both LiFePO₄ and graphite materials, and thus improves the low-temperature performance of LiFePO₄-based Li-ion battery. The Li-ion battery using the optimized electrolyte of 1 mol·L^-1 LiPF₆/EC:EMC:DMC:EP …

Multifunctional Corrosion Inhibition Behavior Of Zn-Al Calcined Layered Double Hydroxides For Steel Rebar In Nacl Solution, Xiao-Juan Zhang, Jing-Jing Wang, Shi-Gang Dong, Chang-Jian Lin

Journal of Electrochemistry

The Zn-Al layered double hydroxides (Zn-Al LDHs) and calcined products (Zn-Al CLDHs) were synthesized successfully under a routine air atmosphere. The results showed that both Zn-Al LDHs and Zn-Al CLDHs had obvious flake structures. The corrosion inhibition of Zn-Al CLDHs for steel rebar in NaCl solution was studied by electrochemical techniques. It was found that the corrosion rate of steel rebar decreased significantly after the steel rebar was treated by Zn-Al CLDHs in NaCl solution for 3 h. It was indicated that Zn-Al CLDHs could absorb Cl^- and release OH^- during their reconstruction process, which provided dual protection …

Influences Of The Cinnamic Acid On Zinc Electrodeposition At Glassy-Carbon Electrode, Kai Li, Shen Chen, Shen-Na Liu, Bi-Sang Chen, Heng Lin, Guo-Liang Chen, Qing-Xiang Wang

Journal of Electrochemistry

The influences of cinnamic acid (CIN) on the mechanism of Zn deposition and nucleation kinetics onto glassy-carbon electrode were studied by cyclic voltammetry (CV) and chronoamperometry (CA). The results revealed that the zinc reduction took place via Zn²⁺ + 2e → Zn in the presence of CIN, but the kinetics of zinc deposition was changed and the formation rate of zinc nuclei was accelerated. In the absence of CIN, the mechanism of zinc nucleation followed the 3D-instantaneous diffusion-controlled nucleation, while the 3D-progressive diffusion-controlled nucleation in the presence of CIN. The addition of CIN reduced the nucleation rate, but increased …

Preparation And Characterization Of A Novel Composite Electrolyte Ceria-Sulfate For Intermediate Temperature Solid Oxide Fuel Cells, Ze Tong, Yi-Mei Yin, Jie-Wei Yin, Zi-Feng Ma

Journal of Electrochemistry

A novel composite electrolyte SDC-(Li/Na)₂SO₄ was prepared for intermediate temperature solid oxide fuel cells (ITSOFC). The phase structure and cross-sectional morphology were examined by XRD and SEM, respectively, and the ionic conductivity was investigated by AC impedance in a temperature range of 400 ^oC ~ 700 ^oC in air. It was found that the composite electrolyte was composed of two phases: crystal SDC and amorphous (Li/Na)₂SO₄. The conductivity of the composite electrolyte was significantly larger than that of SDC at intermediate temperatures (550 ^oC ~ 700 ^oC) and increased …

The Effect Of Precursors On Performance Of Lini0.5Co0.2Mn0.3O2 Cathode Material, Dong-Ge Hu, Zhang-Zhi Wang, Jia-Li Liu, Tao Huang, Ai-Shui Yu

Journal of Electrochemistry

Commercial LiNi_0.5Co_0.2Mn_0.3O₂ material is generally prepared by a combination of co-precipitation and solid state reaction method. The particle size distribution and morphology of Ni_0.5Co_0.2Mn_0.3(OH)₂ precursor have a great impact on the electrochemical performance of LiNi_0.5Co_0.2Mn_0.3O₂. In this work, the crystal structure and surface morphology of LiNi_0.5Co_0.2Mn_0.3O₂ prepared by three different precursors were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Particle size distribution, tap density and electrochemical performance were …

Preparation And Electrochemical Performance Of Hollow Carbon Spheres/Sulfur Composite, Jun Zang, Hang Qian, Er-Man Zeng, Juan-Ni Fu, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

Hollow carbon spheres were prepared by the PMMA template. Hollow carbon spheres/sulfur composite was made from sulfur and hollow carbon spheres as a conducting framework. The results of SEM and TEM showed that sulfur was uniformly filled in both of the shell and hollow core of hollow carbon spheres. The electrochemical performance of hollow carbon spheres/sulfur composite was characterized by the charge/discharge method. The results showed the excellent rate and cycle performance of hollow carbon spheres/sulfur composite. The reversible capacities of hollow carbon spheres/sulfur composite are 1145 mAh·g^-1, 824 mAh·g^-1, 702 mAh·g^-1, 586 mAh·g …

Polypyrrole-Transition Metal-Oxygen Coordination Complexes As High Performance Lithium Storage Material, Ya Mao, Qingyu Kong, Bingkun Guo, Zhaoxiang Wang, Liquan Chen

Journal of Electrochemistry

No abstract provided.

Influence Of Electrode Hydrophobicity On Performance Of Alkaline Polymer Electrolyte Fuel Cells, Li-Sheng Tan, Jing Pan, Yao Li, Lin Zhuang, Jun-Tao Lu

Journal of Electrochemistry

In the present work, we study the influence of the electrode hydrophobicity on the performance of alkaline polymer electrolyte fuel cells (APEFCs). QAPS or xQAPS is employed as the membrane and the ionomer, while PTFE is used as a hydrophobic additive in order to adjust the electrode hydrophobicity. We find that enhancing the hydrophobicity of anode can promote the performance of APEFCs, while a moderate hydrophobicity of cathode is required to achieve optimal performance. By using xQAPS as the electrolyte and adding some PTFE in the anode, a peak power density of 132 mW·cm^-2 can be obtained at a …

Progress Of Lithium Rich Cathode Materials For Li-Ion Batteries, Jie Zhang, Jiu-Lin Wang, Jun Yang

Journal of Electrochemistry

Lithium rich materials xLi₂MnO₃·(1-x)LiMO₂ (0-1 and low cost. However, the large irreversible capacity during the first cycle, low rate capability and structure collapse during cycling remain impediments in developing these cathodes for applications. The structure analyses and charge/discharge mechanisms for lithium rich materials are currently main research contents. Although whether the lithium rich materials are solid solutions or composite is still controversial, oxygen release mechanism on the first charge 4.5 V plateau of lithium rich materials has come to consistency. Several modifications, such as bulk doping, surface coating and microstructure control, demonstrate promising strategies to …

Electrochemical Performance Of Al-Doped Spinel Limn2O4 Cathode Material For Li-Ion Batteries, Yong-Long Wang, Wen-Ge Wang, Qian Zhang, Xin Wang, Jian-Sheng Cao, Shi-Hai Ye

Journal of Electrochemistry

Spinel LiMn₂O₄, a cathode material for Li-ion batteries, is featured as good high-rate performance, low cost and environmental friendly. The pristine and Al-doped LiMn₂O₄ samples were prepared by sol-gel method. The structure and micromorphology of the as-prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results demonstrated that the as-prepared LiMn₂O₄ samples had a typical cubic spinel structure and were composed of sphere-like particles with a diameter range of 300 ~ 500 nm. Galvanostatic charge-discharge tests showed that the LiMn₂O₄ samples doped …

Electrocatalytic Mechanism And Porous Electrode Mass Transfer Process In Membrane Electrode Assembly For Direct Methanol Fuel Cells, Xin-Dong Wang, Yi-Tuo Wang, Gui-Cheng Liu, Meng Wang, Zhe Tian

Journal of Electrochemistry

Direct methanol fuel cell (DMFC) is considered to be a promising commercial energy conversion device for portable electronics due to its many advantages. In order to improve the performance of DMFC, many companies and research institutes have been launching the deep research and obtaining a lot of conspicuous achievements. In this paper, the electrocatalytic mechanism and porous electrode mass transfer process in membrane electrode assembly (MEA) are analyzed. In addition, combined with the preparation process of MEA, multilayer ordered structures and internal transfer process of the cell, recent progresses of MEA in DMFC are discussed.

Electrochemical Nanofabrication Using Polyacrylamide Hydrogel As Soft Stamps, Wen Sun, Hai-Tao Fan, Da-Xiao Zhang, Dong-Jie Hu, Yong-Liang Zhou

Journal of Electrochemistry

The fabrication resolution of electrochemical wet stamping (E-WETS) was enhanced to several hundred nanometers from several ten micrometers by using polycarylamide gel (PAG) as soft stamps and through optimized processes. The PAG stamp was cured on a nanopatterned soft mold and soaked with 0.2 mol·L^-1 KCl solution, then contacted with a silicon wafer with gold film and applied with electric field. And the gold nanopatterns were achieved by the selective anodic dissolving, the diameter of fabricated gold spot was around 200 nm. The parameters which affected the fabrication processes have been discussed in detail.

Fabrication And Performance Of Lani0.6Fe0.4O3-δCathode Modified By Coating With Gd0.2Ce0.8O2 For Intermediate Temperature Solid Oxide Fuel Cell, Rui-Xuan Ren, Bo Huang, Xin-Jian Zhu, Yi-Xing Hu, Xiao-Yi Ding, Zong-Yao Liu, Ye-Bin Liu

Journal of Electrochemistry

The symmetric cell of LaNi_0.6Fe_0.4O_3-δ/Sc_0.1Zr_0.9O_1.95/LaNi_0.6Fe_0.4O _3-δ was fabricated with screen printing method. A LaNi_0.6Fe_0.4O_3-δ (LNF) cathode was modified by coating with nano-sized gadolinium-doped ceria (GDC, Gd_0.2Ce_0.8O₂) prepared using a simple combustion process within the pores of the cathode. According to the electrochemical impedance spectra (EIS), the polarization resistance of the pure LNF was 0.70 W·cm² at 750 ºC, while 0.13 W·cm² for the 21.3% GDC (by mass)-coated LNF cathode at the …

Optimization Of Electroless Silver Plating Process On Fabric Surface Without Activation And Sensitization, Bo Lian Wang, Ya Ping Zhao, Zai Sheng Cai

Journal of Electrochemistry

Silver was deposited homogeneously on the surface of polyamide fabric by electroless plating without activation and sensitization. The electroless silver plating process was optimized with the orthogonal array testing strategy. It is found that the optimum conditions are the electroless plating time of 50 min with the concentrations of silver nitrate, sodium hydroxide and ammonium hydroxide being 14 g·L^-1, 6 g·L-1 and 130 mL·L^-1, respectively. The surface morphologies, compositions, and phases of fabric samples were characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM-EDS), X-ray diffraction (XRD). The wear-resisting property was tested by friction fastness …

Photoionization Mass Spectrometry And Photoelectron-Photoion Coincidence (Pepico) Spectroscopy Studies Of Select Biofuel Molecules, Joseph G. Czekner

Master's Theses

This thesis is the culmination of numerous experiments, performed on two different continents, investigating the spectroscopic and thermodynamic properties of several biofuels and fuel additives. It will start with an introduction about the motivation behind these experiments. The second chapter will outline the experimental details of the apparatus at the Advanced Light Source (ALS) in Berkeley, CA, followed by the Swiss Light Source (SLS) in Villigen, Switzerland. Third, the theoretical concepts and data analysis methods will be discussed in detail.

Chapter 4 will be the start of the newly obtained data. It presents some photoionization mass spectrometry studies on γ-valerolactone …

Probing The Low Temperature Oxidation Of Furanic Biofuels, 2-Methyltetrahydrofuran And 2,5-Dimethylfuran, Utilizing Orthogonal Time-Of-Flight Mass Spectrometry Coupled To Synchrotron Radiation, Matthew Mcmanus

Master's Theses

Concern over natural resources and global climate shifts has increased the focus of sourcing transportation fuels from depleting oil wells to regenerative, biological based solutions. One avenue of biologically sourced fuel involves the extraction of C5 and C6 sugars from the woody, fibrous, and inedible plant materials, otherwise known as lignocellulosic biomass. These cellulosic sugars can be converted to target biofuels and biofuel additives like the furanic compounds, 2,5-dimethylfuran and 2-methylfuran. In this thesis, the low temperature oxidation of two compounds, 2,5-dimethylfuran and 2-methylfuran, are explored. These reactions were conducted at the Advanced Light Source in Berkeley, CA and used …

Why Do Molecules Echo Atomic Periodicity?, Ray Hefferlin, Jonathan Sackett, Jeremy Tatum

Faculty Works

Franck–Condon factors are investigated for sequences of free

main-group diatomic molecules. Theory-based Condon loci

(parabolas) and Morse-potential loci are plotted on Deslandres

tables to verify if they, indeed, follow the largest Franck–Condon

factors. Then, the inclination angles of the Condon loci

are determined. Thus, entire band systems are quantified by

one variable, the angle. For all available isoelectronic sequences,

this angle increases from a central minimum toward

magic-number molecular boundaries. The theory for the Condon

locus gives the angle in terms of the ratio of the upperstate

to the lower-state force constants. It is concluded that

the periodicity is caused …

Fused Arenes-Based Molecular And Polymeric Materials For Organic Field Effect Transistors, Harista Irugulapati

Masters Theses & Specialist Projects

In the past decade, tremendous progress has been made in organic field effect
transistors. Fused oligothiophenes and anthracene molecules are fascinating
macromolecules having unique optoelectronic properties. These compounds are successfully employed as active components in optoelectronic devices including field effect transistors. Our goal is to design and synthesize conjugated molecular materials, which are highly functionalized through structural modifications in order to enhance their electronic, photonic, and morphological properties. The main desire is to synthesize novel organic fused-arenes having efficient charge carrier mobilities, as well as to optimize optical properties for organic field effect transistors (OFETs). Novel series of fused arene …