Physical Chemistry Commons^™

Maxwell's Equations, Part Iv, David W. Ball

Chemistry Faculty Publications

In this column, we continue our explanation of Maxwell’s equations, the seminal classical explanation of electricity and magnetism (and, ultimately, light). For those of you new to the series, consider finding the last few appearances of this column to get caught up. Alternately, you should be able to find past columns on our website, www.spectroscopymag.com and look for “The Baseline” link. Words of warning: for my own reasons, the figures are being numbered sequentially through this series of columns, which is why the first figure in this column is numbered 26. Also, we’re going to get a bit mathematical. Unfortunately …

The Tetrafluoroborate Salt Of 4-Methoxybenzyl N-2-(Dimethylamino)Ethyl-N-Nitrosocarbamate: Synthesis, Crystal Structure And Dft Calculations, Helene Hedian, Vladimir Benin

Chemistry Faculty Publications

The tetrafluoroborate salt of 4-methoxybenzyl N-2-(dimethylamino)ethyl-N-nitrosocarbamate was prepared in two steps, via the corresponding carbamate. Its crystal structure is monoclinic, space group P21/c. The unit cell dimensions are: a = 19.499(8) Å, b = 5.877(3) Å, c = 15.757(7) Å, α = 90°, β = 110.019(7)°, γ = 90°, V = 1696.5(12) Å3, Z = 4. The structure exhibits an unexpected, pseudo-gauche conformation with respect to the C2–C3 bond, due to a stabilizing hydrogen bond between the carbonyl oxygen (O1) and the hydrogen atom at the trialkylammonium center (H3n), with a distance between them of …

First-Principles Studies On Physical And Chemical Properties Of Nanostructures, Menghao Wu

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The physical and chemical properties of decorated graphene and graphene ribbons, single-layer III-V systems, three-dimensional carbon and BN foam, and transition-metal-molecular sandwich nanowires have been investigated by first-principle calculations and their potential applications have been predicted. First, it is shown that zigzag graphene nanoribbons (ZGNRs) can be converted into half metal when their edges are decorated by some chemical functional groups, and the half-metalicity is induced by chemical potential difference between two edges when one edge is decorated by electron-donating group like –OH and the other edge is decorated by electron-accepting group like –F, -NH₂, -N(CH₃) …

Quantum Mechanical And Molecular Mechanical Study Of Solvent Effects, Dejun Si

Department of Chemistry: Dissertations, Theses, and Student Research

Intermolecular interaction and solvent effects play important roles in determining physical and chemical properties of molecular systems, and must be considered in relevant quantum mechanical (QM) calculations. Due to the high computational cost, full and rigorous QM treatment of both solute and solvent molecules is impractical. Computationally efficient molecular mechanical (MM) methods can be used to describe solvent effects, and combined into QM methods to formulate QM/MM methods. Classical force field method and reaction-field method are the two most popular MM methods. However, the issue of effectively combining MM methods with high-level QM methods remains unsolved. This thesis presents several …

Preparation And Application Of Nano-Nio As Anode In Lithium-Ion Batteries, Cheng-Dong Bai, Jia-Jia Chen, Qi Zhang, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

In this work, the nano-NiO material was prepared by hydrothermal method. The surface morphologies and electrochemical properties of nano-NiO material were investigated. The special nano-NiO material with porous surface assembling honeycombs(100-200nm) was obtained by using surface active agents. The discharge capacity of nano-NiO electrode up to 2385.7 mAh/g was achieved at current density of 0.1A/g in the first circle,while 1100mAh/g could be maintained after 100 circles. At current density of 2.0A/g, the discharge capacity of 600 mAh/g was obtained. And when the current density was reduced to 0.1A/g, the discharge capacity was restored to 1050 mAh/g. The nano-NiO electrode exhibited …

Corrosion Behaviors Of 316 Stainless Steel Weldment Studied By Array Reference Electrodes, Wang-Huo Yang, Rong-Gang Hu, Chen-Qing Ye, Wei Hang, Ning Li, Chang-Jian Lin

Journal of Electrochemistry

The array reference electrodes were developed to in situ measure the potential distributions of the welded 316 stainless steel in 12% FeCl3 solution, combined with metallographic analysis, polarization curve, EIS measurement and Kelvin volta potential imaging. It was indicated that the weld zone of metal suffered a serious preferential corrosion when immersed in the environment due to the distinct changes of structure and composition during the welding process. With time prolonging, the corrosion potential of the welding zone was negatively shifted to a maximum value, and then declined gradually. At 45 min immersion, the corrosion development from welding zone to …

Microemulsion Preparation And Electrochemical Characterization Of Pt/C, Ptir/C Electrocatalysts, Ya-Ping Zeng, Sheng Sui

Journal of Electrochemistry

The Pt/C electrocatalysts were prepared by three different systems and the PtIr/C electrocatalysts were prepared with four different Ir contents. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), cyclic voltammetry (CV), potentiostatic and potentiodynamic polarizations measurements. The experimental results confirmed that the electrocatalyst particles prepared by the microemulsion method were well distributed on XC-72R supports with the active particle sizes of 5～10nm and good electrocatalysts activity. The Pt85Ir15/C electrocatalysts showed the highest overall electrochemical activity in unitized regenerative fuel cell.

Preparation And Characterization Of Casno3 Anode Material For Lithium Ion Batteries, Ran Sun, Zi-Geng Liu, Ya-Qi Jiang

Journal of Electrochemistry

In this study the precursor CaSn(OH)₆ was prepared via a hydrothermal process, and its composition, surface feature and phase-transition were characterized by XRD, SEM and DSC-TGA. The shapes of CaSn(OH)₆ crystals were effectively controlled by adjusting the volumn ratio of H₂O and CH₃CH₂OH solvents. Perovskite CaSnO₃ could be obtained by calcination of CaSn(OH)₆ at 800 ℃. The reversible capacity of 334.4 mAh/g with good cycling stability could be achieved with the CaSnO₃ electrode.

Preparation And Characterization Of The Lani0.6Fe0.4O3-δ Cathode For Intermediate Temperature Solid Oxide Fuel Cell, Hang Liu, Bo Huang, Xin-Jian Zhu

Journal of Electrochemistry

The LaNi_0.6Fe_0.4O_3-δ as cathode material for intermediate temperature solid oxide fuel cell was prepared using a combustion synthesis technique. The X-ray diffraction (XRD) pattern showed that the single-phase LaNi_0.6Fe_0.4O_3-δ perovskite could be obtained after heat treatment at 600°C. The TEM and SEM images of the synthesized powders revealed that the grains were 50-100nm. According to the electrochemical impedance spectra (EIS), the polarization resistance of the symmetric cell LaNi_0.6Fe_0.4O_3-δ/ScSZ/LaNi_0.6Fe_0.4O_3-δ sintered at 1050°C was the smallest (0.70Ω·cm², 0.27Ω·cm^{2 …}

Preparation And Application Of Macroporous Ato/Sio2 Electrode In Electrochemical Degradation Of 4-Chlorophenol, Zhang-Lin Chai, Rui-Feng Zhang, Tong-Hu Xiao, Yun-Xiao Liang

Journal of Electrochemistry

The macroporous ATO/SiO₂ materials were prepared through multiple steps of hydrolysis deposition in ethylene glycol and acetonitrile mixed solutions of SnCl₂/SbCl₃ and subsequent calcination at high temperature. The structures of the obtained materials were characterized by means of SEM and XRD. The results showed that the nano-ATO chemically deposited on the SiO₂ support underwent well-controlled aggregation and recrystallization to form a sandwich structure (ATO-SiO₂-ATO). Through four times loading of ATO the volume resistivity and the specific surface area reached 10·cm and 77 m²·g^-1, respectively. The oxygen evolution potential on …

Dynamic Modeling And Characteristic Analysis Of Proton Exchange Membrane Fuel Cell, Qiu-Hong Jia, Ming Han, Bin Deng, Cai-Zhi Zhang

Journal of Electrochemistry

In this paper, a dynamic model of PEMFC is developed to estimate the dynamic performance of PEMFC by analyzing in detail the influence factors of voltage of PEMFC including various losses. The partial pressure of hydrogen and oxygen is obtained using the differential form of the ideal-gas equation in this model. The steady-state model is obtained by setting reasonable parameter values. The simulation results and experimental results have good consistency, which shows that the simulation model is correct, reasonable and effective. It analyzed the dynamic response characteristics of the output voltage and the partial pressure of hydrogen in condition of …

Preparation And Capacitance Characteristics Of Nickel Oxide Electrode With Mesh-Like Structure, Hui Xu, Zhen-Jun Peng, Dong-Hong Guo, Jun-Ling Li

Journal of Electrochemistry

The mesh-like structure of NiO electrode was obtained by first preparing the precursors via hydrothermal process using nickel sulfate and carbamide as reactants, sodium hexametaphosphate as a surfactant, and followed by calcination of the precursors at 400 ℃. The structure, morphology and capacitance characteristics of NiO electrode were characterized by XRD, SEM and constant current charge-discharge testing techniques. The effects of hydrothermal temperatures on the electrochemical properties of NiO electrode were investigated. The results showed that the better property of nickel oxide was obtained when the mole ratio of nickel to urea was 1:4 and the hydrothermal temperature was 140℃. …

A Brief Review Of Research Progress In The Development Of Engineering Models For Lithium Ion Batteries, Da-Wei Wang, Dong-Jiang Li, Jun Li, Yong Yang

Journal of Electrochemistry

Lithium ion battery has become an important and popular electrochemical device for energy storage.Suitable evaluation and understanding of electrochemical performance and state of charge play a key role in the applications of lithium ion batteries.Construction and utilization of engineering modeling for lithium ion batteries is an effective way to fulfill this target.In this paper,engineering models of lithium ion batteries based on electrochemical reaction,ionic diffusion and migration are introduced.The emphasis is placed on the development of engineering models by the introduction of side reaction,phase transition,stress and energy.The applications of engineering models in such simulations as charge-discharge,concentration distribution,current distribution,state of charge,stress and …

Brief Introduction Of Organic Electrochemistry, Huan Wang, Jia-Xing Lu

Journal of Electrochemistry

Organic electrochemistry is a very useful tool for organic synthesis, not only because of the selective introduction or removal of electrons from organic molecules, but also for its green process. In this paper, electroorganic synthesis has been introduced from the systems, research methods and technologies to the characterization. Most of organic compounds could be electrochemically oxidized or reduced. Here, taking C=C compounds as an example, several kinds of electrochemical organic synthesis reactions are discussed, such as electrochemical addition, electrocatalytic dimrization, electropolymerization, etc. Electroorganic synthesis has been industrialized since 1960s. In this paper, electrosynthesis of adiponitrile was used as an example …

Electroless Plating Silver Without Pd Activation On Polyamide Fabrics And Its Properties, Yun Meng, Ya-Ping Zhao, Zai-Sheng Cai

Journal of Electrochemistry

Silver was deposited on the surface of polyaniline coated polyamide fabrics by electroless plating without using conventional palladium chloride solution as activator．Effects of electroless plating conditions such as the concentrations of silver nitrate, reducing agent glucose, complexing agent ammonium hydroxide, sodium hydroxide in the bath, as well as the depositing time and bath temperature on the rate of metal deposition and the square resistance were studied. Optimum electroless plating conditions were: 30℃, 50 min, with silver nitrate 12 g/L, ammonium hydroxide 100 ml/L, glucose 2.8 g/L, sodium hydroxide 8 g/L. Meanwhile, effects of the intermediate polyaniline layer on the metal …

Superhydrophilic/Superhydrophobic Surface Constructions On Titanium And Their Effects On Anti-Bacterial Properties, Guo-Wei Wang, Qiao-Ling Huang, Ren Hu, Chang-Jian Lin, Hao Wang, Li-Hai Zhang, Pei-Fu Tang

Journal of Electrochemistry

The microbial infection of biomaterials often causes clinic problems and sometimes even leads to the prosthesis failure. It is, therefore, important to prevent the biomaterials from bacterial contamination. This can be done by using anti-bacteria drugs. However, this method causes physiological burdens to the patients and does not always work. To stop the contamination from the just beginning is believed to be a better choice. The first step for infection is the attachment of bacteria on the material. In this work, the thin TiO₂ nanotubes array films were constructed with totally different wettabilities showing either superhydrophobic or superhydrophilic. The …

The Electrochemical Properties Of Cathode Materials LimXV3-XO8, Hui Yang, Gang-Gang Zhao, Juan Li

Journal of Electrochemistry

The cathode material of LiM_xV₃-xO₈ was fabricated by sol-gel method using citric acid as a chelating agent and doping transition metal ions M (Mn, Ti, Co and Ni). The structure, morphology and electrochemical proprieties of the LiMxV3-xO8 samples were investigated by XRD, TGA/DTA, SEM, charge-discharge and CV measurements. The results showed that different calcining temperatures result in different structures and morphologies, which lead to different discharge capacities. The specific discharge capacity of the sample calcined at 500℃ for 6 h was up to 300.4 mAh/g in the first cycle, and the capacity decreased with the …

Electrocatalytic Determination Of 15 Kinds Of Phenolic Compounds By Novel Gold Nanoparticles-Modified Glassy Carbon Electrode, Yan-Ping Cui, Wei-Xing Wang, Chang-Zhu Yang, Wen-Hong Pu

Journal of Electrochemistry

A gold nanoparticles modified glassy carbon electrode (Au/GCE) was used to detect 15 kinds of phenolic compounds. In the cyclic voltammetry measurements, the peak currents of phenolic compounds at Au/GCE were all increased as compared with GCE and planar gold electrodes, and the oxidation potentials were determined by the activity of analytes. Besides, electrocatalysis of salicylic acid was studied at Au/GCE. The results showed that, there was a good linear relationship between the oxidation current and the concentration of salicylic acid, and the current sensitivity was 1.8 fold higher than that obtained on GCE. Trace phenolic compounds determination could be …

Electrochemical Properties Of Tungstogermanate And Electrocatalysis Of H2O2 On Gew11Co/P-Opd/Gc Electrode, Li-Li Zhu, Jian-Ying Qu, Jue Wang, Hao-Yue Feng

Journal of Electrochemistry

The electrochemical properties of Co-substituted trimeric tungstogermanate containing Keggin fragments were studied. Cyclic voltammograms revealed two couples of reversible redox peaks on glassy carbon (GC) electrode in acid solutions. They corresponded to two-electron reductions accompanying by the additions of four protons and three protons, respectively, both were controlled by adsorption. The differences in the peak potentials of 2-electron-4-proton and 2-electron-3-proton reactions were 31 mV and 35 mV, respectively..Furthermore, the tungstogermanate (GeW11Co) modified GC electrode with functionalization by poly(o-phenylenediamine) (P-oPD) was prepared readily by electropolymerization. The GeW11Co/P-oPD/GC electrode could electrocatalyze the reduction of hydrogen peroxide, which showed good stability and quick …

Electrochemical Studies On Surface Inclusion Of Β-Cyclodextrin With Adriamycin, Jian Shi, Qi-Ping Zhang, Nan-Ping Wang

Journal of Electrochemistry

The β-cyclodextrin (β-CD) modified gold electrode (β-CD/Au) was fabricated to study the electrochemical behavior of adriamycin (ADM). The results indicated that the complexing reaction of ADM with β-CD took place at the β-CD/Au surface. At 25 °C, the complexing constant (K) was 9.54×10⁴ L·mol^-1 in pH=7.0. The K values changed regularly with temperature, and the most suitable temperature of the surface inclusion reaction was 30 ℃. The complexing reaction of ADM with β-CD at the β-CD/Au surface could undergo the quasi-reversible electrochemical reaction with the rate constant being 0.0995 s^-1. The cathodic peak current (Ip) of …

Indirect Electrochemical Reduction And Cotton Dyeing Process In Fe(Ⅲ)-Oxalate-Calcium Gluconate System, Qing-Zhi Wang, Wei Wang

Journal of Electrochemistry

The electrochemical behavior and possible reaction mechanism in Fe(Ⅲ)-oxalate-calcium gluconate system were studied by cyclic voltammetry. The results showed that Fe(Ⅱ)-gluconate was the final reductant. The reduction time, the working voltage and the cathode area influenced the current efficiency. The high current efficiency of 89% for the indirect electrochemical reduction of Vat Scarlet R could be achieved with reduction time of 10 min, working voltage of 4 V and cathode area of 40 cm² in Fe(Ⅲ)-oxalate-calcium gluconate system.

Electrochemical Behaviors Of Hydroquinone On Polypyrrole/Stab-Nammt/Gc Electrode, Rong Li, Jian Xiong, Wei-Qiong Zhu, Yuan-Yuan Han, Jin Xu, Xiao-Ying He

Journal of Electrochemistry

The PPy/STAB-MMT/GC electrode was made using montmorillonite modified by STAB and polypyrrole (PPy). The electrochemical behaviors of hydroquinone on the PPy/STAB-MMT/GC electrode were researched by cyclic voltammetry and square wave stripping voltammetry (SWSV). The results showed that the electrode reaction occurred on the hydroquinone electrode was controlled by diffusion in PBS (pH=6.0). The number of electron transfer was equal to the number of protons (n=m=1) with the effective area of PPy/STAB-MMT/GC electrode Aeff=0.031 cm². Under the optimized conditions, the linear response of peak current in SWSV with the concentration of hydroquinone in a range of 8.0×10^-6~8.0×10 …

Chemical Activity In Yba2cu3o7 − Δ Across The Normal To Superconducting Phase Transition, Juana Vivó Acrivos

Faculty Publications, Chemistry

The Gibbs free enthalpy, chemical activity across the transition temperature to superconductivity, Tc in YBa2Cu3O7 − δ is obtained from reciprocally enhanced X-Ray absorbance, XAS and diffraction, XRD data near the Ba L3,2 edges' energy Ea, and orientations in the X-ray beam for preferred Miller indexed [HKL] planes' scattering, that are enhanced near Tc. The standard enthalpy and entropy for the formation of mixed normal metal/superconducting domains above Tc, determined individually across the two Ba L3,2 edges, to better than a percent accuracy: ΔH≠≥ = − 220 meV, and ΔS≠≥ = − 2 meV/K when 121 ≥ T ≥ 92 …

Reactive Quenching Of Od A (2)Σ(+) By H-2: Translational Energy Distributions For H- And D-Atom Product Channels, J. H. Lehman, Jesse Lyle Bertrand , '11, Thomas Alex Stephenson, M. I. Lester

Chemistry & Biochemistry Faculty Works

The H- and D-atom products from collisional quenching of OD A (2)Sigma(+) by H-2 are characterized through Doppler spectroscopy using two-photon (2 S-2 <-<- 1 S-2) laser-induced fluorescence. Partial deuteration enables separation of the channel forming H + HOD products, which accounts for 75% of reactive quenching events, from the D + H2O product channel. The Doppler profiles, along with those reported previously for other isotopic variants, are transformed into product translational energy distributions using a robust fitting procedure based on discrete velocity basis functions. The product translational energy distribution for the H- atom channel is strongly peaked at low energy (below 0.5 eV) with a long tail extending to the energetic limit. By contrast, the D-atom channel exhibits a small peak at low translational energy with a distinctive secondary peak at higher translational energy (approximately 1.8 eV) before falling off to higher energy. In both cases, most of the available energy flows into internal excitation of the water products. Similar distributions are obtained upon reanalysis of D- and H- atom Doppler profiles, respectively, from reactive quenching of OH A (2)Sigma(+) by D-2. The sum of the translational energy distributions for H- and D- atom channels is remarkably similar to that obtained for OH A (2)Sigma(+) + H-2, where the two channels cannot be distinguished from one another. The product translational energy distributions from reactive quenching are compared with those obtained from a previous experiment performed at higher collision energy, quasiclassical trajectory calculations of the post-quenching dynamics, and a statistical model. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3644763]

Preparation And Characterization Of A Composite Of Gold Nanoparticles And Single-Walled Carbon Nanotubes And Its Potential For Heterogeneous Catalysis, Anne Shanahan, James Sullivan, Mary Mcnamara, Hugh Byrne

Articles

A single-walled carbon nanotube-supported gold nanoparticle composite was prepared and characterized by X-ray diffraction, scanning transmission electron microscopy/scanning electron microscopy/transmission electron microscopy, energy-dispersive X-ray analysis, atomic absorption spectroscopy, nitrogen adsorption, Raman spectroscopy, and ultraviolet-visible spectroscopy. The Au particles were found to be crystalline, with a well-defined and narrow particle-size distribution, centered around 7 nm. The activity and selectivity of the composite for solventless aerobic oxidation of a secondary alcohol were examined, and a conversion efficiency of 95% was obtained.

Excellent Adventures In Global Collaboration, Glenn W. "Max" Mcgee, Aracelys Rios

Publications & Research

No abstract provided.

I. The Synthesis And Coordination Chemistry Of Novel 6Π-Electron Ligands. Ii. Improvement Of Student Writing Skills In Chemistry Lab Reports Through The Use Of Calibrated Peer Review, Wilson Ngambeki William

Chemistry and Chemical Biology ETDs

ABSTRACT I

The goal of this study was to synthesize and characterize a set of coordination complexes containing 6π-cationic ligands. These compounds could be extremely useful as catalysts for the polymerization of olefins that are widely used in the synthetic polymer industry. The original strategy was to synthesize the 6π-cationic ligands using (Ph₂P)₃CH (1) and (Me₂P)₃CH (10) as precursors; however, both precursors 1 and 10 were found to be highly reactive leading to the fragmentation products (Ph₂P)₂CH₂ and (Me₂P)₂CH₂ respectively. In trying …

Structural Characterization Of Metal Binding In Metallo-Β-Lactamases Using X-Ray Absorption Spectroscopy, Robert M. Breece

Chemistry and Chemical Biology ETDs

In an effort to probe the structure and mechanism of metallo-β-lactamases, the metal-binding behaviors of several enzymes were studied using EXAFS (Extended X-ray Absorption Fine Structure). Three members of the metallo-β-lactamase subclass B1, BcII from Bacillus cereus, Bla2 from Bacillus anthracis and CcrA from Bacillus fragilis, were compared to examine metal-binding behavior within a subclass. Each system exhibits different metal-binding behavior including cooperative binding (BcII), sequential binding (CcrA), and differential binding between zinc(II) and cobalt(II) forms (Bla2). The metal-binding behavior of subclass B3 of L1 from Stenotrophomonas maltophilia was explored with RFQ (rapid-freeze quenched) EXAFS and site selective metal …

Study On Residual Powders Of Lithium-Ion Batteries With Different Voltages After Explosion, He Li, Zhi-Kui Chen, Ji-Na Cao, Guang-Chuan Liang

Journal of Electrochemistry

The residual powders of lithium-ion batteries at different voltages after explosion were obtained by using the battery impact testing machine. And these powders have been investigated by weighing, water solution and X-ray diffraction (XRD). The results showed that the integrity status of copper current collector and weight of residual powders decreased gradually with increasing of battery voltage, rising of burning temperature and releasing of burning duration time. The residual powders could be separated to insoluble powders and soluble powders by the water solution. The proportion of the insoluble powders is more (about 90%) including C, Co and CoO, while the …

Development Of Dehydrogenase-Based Bioanode Using Poly(Phenosafranin)-Functionalized Swcnt Nanocomposites And Its Application To Ethanol Biosensor, S. Saleh Farhana, Okajima Takeyoshi, Lanqun Mao, Takeo Ohsaka

Journal of Electrochemistry

A New type of dehydrogenase-based amperometric ethanol biosensor was constructed using alcohol dehydrogenase (ADH) which was immobilized on the edge-plane pyrolytic graphite (EPPG) electrode modified with poly(phenosafranin)-functionalized single-walled carbon nanotube (PPS-SWCNT). The PPS-SWCNT modified EPPG electrode was prepared by electropolymerization of phenosafranin on the EPPG electrode which was previously coated with SWCNT. The performance of the ADH/PPS-SWCNT/EPPG electrode was evaluated using cyclic voltammetry and amperometry in the presence of ethanol. The fabricated ethanol biosensor provided a reasonable sensitivity of 2.0 μA cm–2 mM–1 and a low detection limit (36 μM) for the electrocatalytic oxidation of ethanol with a linear concentration …