Chemistry Commons^™

Inverse Velocity Dependence Of Vibrationally Promoted Electron Emission From A Metal Surface, N. H. Nahler, J. D. White, Jerry L. Larue, Daniel J. Auerbach, Alec M. Wodtke

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

All previous experimental and theoretical studies of molecular interactions at metal surfaces show that electronically nonadiabatic influences increase with molecular velocity. We report the observation of a nonadiabatic electronic effect that follows the opposite trend: The probability of electron emission from a low–work function surface—Au(111) capped by half a monolayer of Cs—increases as the velocity of the incident NO molecule decreases during collisions with highly vibrationally excited NO(X²π_½, V = 18; V is the vibrational quantum number of NO), reaching 0.1 at the lowest velocity studied. We show that these results are consistent with a vibrational …

Electrocatalytic Performance Of Carbon Supported Au-Ir Catalyst As Cathodic Catalyst In Direct Formic Acid Fuel Cell, Wei Chen, Ya-Wen Tang, Tain-Hong Lu

Journal of Electrochemistry

In this paper,it is reported for the first time that the electrocatalytic activities of the carbon supported Au(Au/C),carbon supported Ir(Ir/C) and the carbon supported Au-Ir(Au-Ir/C) catalysts prepared in the aqueous solution with tetrahydrofuran(THF) for the oxidation of formic acid and for the oxygen reduction were compared.It was found that all three catalysts showed no electrocatalytic activity for the oxidation of formic acid,but the electrocatalytic activity of the Au-Ir/C catalyst for oxygen reduction was much better than those of Au/C and Ir/C.Thus,the Au-Ir/C catalyst is suitable to be used as the cathodic catalyst in Direct formic acid fuel cell(DFAFC).

An Hap/Nanosilver Coating Prepared By Electrochemical Deposition And Its Antibacterial Characterization, Zhi-Wang Geng, Hui Wang, Chang-Jian Lin

Journal of Electrochemistry

The silver nanoparticles were prepared by sodium citrate reduction of AgNO₃.The nanoparticles were electrophoretic deposited on titanium, followed by the electrolytic deposition of hydroxyapatite(HAp). It is revealed, by the high-resolution transmission electron microscopy(HRTEM), that the diameters of nanosilver particles ranged from 5nm to 20nm. The XPS and XRD indicated the coating consisting of silver and HAp. According to the SEM images and antibacterial test, it is demonstrated that when the concentrations of the electrophoretic solution became higher more silver particles were depostited, and the antibacterial property improved. However, the particles aggregated on titanium greatly when the concentration exceeded …

Preliminary Study Of Single Flow Zinc-Nickel Battery, Li Zhang, Jie Cheng, Yu-Sheng Yang, Yue-Hua Wen, Xin-Dong Wang, Zi-Li Xie

Journal of Electrochemistry

The micromorphology of zinc electrodeposited at different currents in the flowing electrolyte was studied.It has been shown that the structure of the zinc became compacted with the increase of the charge current density and no zinc dendrite was presenct.A cell with 2Ah capacity was assembled and the charge-discharge test was performed.The results showed that the average charge voltage was 1.84V and the average discharge voltage was 1.65V.The high efficiencies can be achieved with an average coulombic efficiency of 97% and energy efficiency of 86% over 1000 cycles.

Electrochemical Reductive Behaviors Of 3,4,5,6-Tetrachloro-2-Trichloromethylpyridine At Ag Electrode, Chun-An Ma, Yi-Jiao Hu, Ying-Hua Xu

Journal of Electrochemistry

The electrochemical reductive behavior of 3,4,5,6-tetrachloro-2-trichloropyridine(heptachloropyridine) on silver electrode in the mixture of acetonitrile and water solutions containing TBAP was investigated by cyclic voltammetry.The influences of scan rate,concentration and temperature on the electrochemical behavior were discussed.It was shown that the reduction of heptachloropyridine on the silver electrode was a diffusion-controlled irreversible process.The diffusion coefficient of heptachloropyridine in the acetonitrile solution was 3.0×10^-5 cm²/s.The mechanism of the dechloration of 3,4,5,6-tetrachloro-2-trichloropyridine was also discussed.

The Effect Of Ru: Sn On Properties Of Ru-Ir-Sn Oxide Anode Coatings, Lei Ji, Jun-Tao Wang, Wen-Bin Liu, Li-Kun Xu, Gui-Lin Xue

Journal of Electrochemistry

The anode coatings of Ru-Ir-Sn oxide with different Ru/Sn ratios were prepared by sol-gel method.The influences of Ru/Sn ratio on properties of anode coatings were studied by scanning electron microscope(SEM),energy dispersive X-ray detector(EDX),X-ray diffraction(XRD).The potential of chlorine evolution,current efficiency,accelerated life,cyclic vohammetry and electrochemical impedance spectroscopy(EIS) tests were carried out.The results showed that there was an obvious effect of Ru/Sn ratio on the morphology of the coatings.The cyclic voltammogram,double layer capacitances and accelerated life of anode coatings had a tendency to fall down firstly then increased as the Ru% increased,the current effency and potential of chlorine evolution had a tendency to …

Hydrolysis Of Sodium Borohydride By Ru-Ni Foam Catalyst, Jie Cheng, Feng Ye, Tong-Tao Wang, Jing-Jing Li, Yong-Liang Wang, Xin-Dong Wang

Journal of Electrochemistry

This paper presented a method of hydrogen generation from sodium borohydride solution for fuel cells.The Ru-Ni foam catalyst which was prepared by chemical plating showed strong activity and stability.The pretreatment of Ni foam before chemical plating was very important for the catalyst's strong activity and stability.This easy-to-prepared catalyst exhibited a good activity after being used several times.The effects of NaBH₄ concentration,temperature and used times on the hydrogen generation rate were investigated.The results showed that the rate was remarkablely increased with the temperature rising and the rate increased more than ten times when the temperature of reaction rised from 15 …

Study On Electrocatalytic Oxidation Of Salbutamol At Carbon Nanotubes Modified Electrode, Ying-Liang Wei, Lu-Ping Zhang, Chen Shao, Hui Feng, Xian-Li Li

Journal of Electrochemistry

The multi-wall carbon nanotubes(MWNT) were dispersed successfully into water in the presence of dihexadecyl hydrogen phosphate(DHP) and a stable well-distributed suspension.A was formed sensor based on the multi-carbon nanotubes film coated glassy carbon electrode was developed.The electrochemical response of salbutamol was studied by square wave voltammetry.The oxidation peak potential of salbutamol at the modified electrode was observed at 0.604 V,which shifted about 40 mV negatively.The peak current increased 4.5 folds,in contrast to that at a bare electrode.Under optimal measurement conditions,there was a good linear relationship between the peak current(Ipa) and salbutamol concentration(C) in the range from 8.3 × 1 0 …

The Endpoint Determination In Hydrochloric Pickling By Electrochemistry Method, Shu-Jie Chen, Chun-Jie Ye, Hong-Liang Pan

Journal of Electrochemistry

Pickling is an effective way to remove the oxide scale covered on steel materials.It is vital to determine the endpoint in the course of pickling process investigation.According to the reaction process of the oxide scale covered on hot-rolling strips with the hydrochloric acid,a method for determining the endpoint of pickling based on electrochemical principle was suggested.In the pickling experimentation of hot-rolling strips,an accurate precision can be obtained using this method.

A Study Of Pd-Ir On Nickel Foam Cathode For Aluminum-Hydrogen Peroxide Semi-Fuel Cells, Ding-Wang Zhu, Dan-Dan Chen, Bi-Jin Li, Gui-Ling Wang, Dian-Xue Cao

Journal of Electrochemistry

The Pd-Ir/Ni electrodes were prepared by electrodeposition of Pd and Ir on the porous nickel foam surface.The structure,composition and state of the Pd-Ir catalyst were analyzed using SEM and XPS.The catalytic performance of Pd-Ir/Ni for H₂O₂ electroveduction at different concentrations of H₂O₂ were investigated.A limiting current density of 318 mA/cm² was obtained with 0.4 mol/L H₂O₂.The aluminum-hydrogen peroxide semi-fuel cells using different aluminum alloys as anode and Pd-Ir/Ni as cathode were assembled and tested.It was found that the fuel cell with aluminum-manganese alloy anode demonstrated a maximum power density …

Electrocatalytic Oxidation Of Salicylic Acid At Novel Gold Nanoparticle-Modified Glassy Carbon Electrode, Yan-Ping Cui, Chang-Zhu Yang, Jian Huang, Wen-Hong Pu, Jing-Dong Zhang

Journal of Electrochemistry

A gold nano-particles modified glassy carbon electrode(GNP/GCE) was prepared by the"seed-mediated gold nano-particles growth method".Field emission scanning electron microscopy,ultraviolet-visible(UV-vis) spectroscopy analysis and electroalaylsis were employed to study the morphology and electrochemical performances.The resulting electrode showed excellent electro-catalytic activity toward the oxidation of salicylic acid and the response sensitivity was 1.8 fold than that obtained on GCE.Good linear relationship was obtained between response current and salicylic acid concentration in the range of 5.0 × 10^-7 ~8.0 × 10^-5 mol/L,which could be used in the detection of trace salicylic acid.

Direct Electrochemistry Of Hemoglobin Immobilized On The Electrode Modified With Ionic Liquid And Kgm, Liu Yang, Xia-Qin Wu, Wen-Jing Hou, Lin-Fei Gu, Rong Wang, Xiao-Ming Guo, Zong-Rang Zhang

Journal of Electrochemistry

Hemoglobin(Hb) has been immobilized on a glassy carbon electrode(GCE) surface with konjac glucomannan(KGM) and room temperature ionic liquid(RTIL).And which electrochemical behaviors have been investigated by cyclic voltammetry.The results shown that the entrapped Hemoglobin undergoes fast direct electron transfer reactions with formal potential of-0.38V(vs.SCE) and the E0' is linearly dependent on solution pH with a slope value of 51 mV/pH,due to the electron transfer of HbFe³⁺/HbFe²⁺ redox couple companied with a proton transfer.The electrocatalytic reduction of oxygen was also explored at the Hb-KGM/RTIL/Nafion/ GC electrode.

Performance Of Magnetic Field Coupled With Electrochemical Process For Preparing Polyaluminum Chloride, Ke-Wu Pi, Wen-Qi Gong, Zheng-Qing Huang

Journal of Electrochemistry

Polyaluminum chloride(PAC) was prepared by electrochemical process coupled with magnetic field paralleling to the gravitation direction.The electrolyte of 0.1 M AlCl3 solution was used,with the iron plates as cathode and aluminum sheets as anode.PAC of 0.6 M total aluminum(AlT),83.2% Alb to AlT and basicity(Ba)=2.4 was synthesized when magnetic flux density was 0.4T,the distance of electrodes was 15 mm,the voltage of electrolysis cell was 2.4 V and current density was 300 A/m2.Under above experimental conditions,the voltage efficiency,energy efficiency and electrodes surface area to reduction cells of electrochemical reactor were 85.2%,81.5% and 140.1m2/m3,respectively.The polarization curves determined by constant-current method showed that the …

Applications Of Electroless Deposition Ni-Cu-P Coating On The Gas Condensing Exchanger, Li-Jun Yang, Gui-Chang Liu, Sui-Lin Wang, Zhi-Cong Shi

Journal of Electrochemistry

The effects of copper sulfate concentration in the plating solution on the composition,the structure and the anticorrosion properties of Ni-Cu-P deposited coating were studied by EPMA, XRD and polarization curves.The anticorrosion properties of Ni-Cu-P deposited coating was optimal as the copper sulfate concentration in the plating solution was 0.5 g·L^-1. The electrochemical anticorrosion properties of Ni-Cu-P, Ni-P deposited coatings and copper plates were investigated in the gas condensate. The self-corrosion potential of Ni-Cu-P deposited coatings was low, the self-corrosion current density was small, and the electrochemical impedance was the highest. Therefore, the electroless Ni-Cu-P coatings can be used …

Study Of Triethyl Phosphate Self-Assembled Films On Iron For Corrosion Inhibition, Wen-Juan Guo, Shen-Hao Chen, Wei He, Xue-Hui Pang, Yuan-Yuan Feng

Journal of Electrochemistry

The self-assembled film of triethyl phosphate(TEP) formed on the iron surface was found to protect iron from corrosion in 0.5 mol·L^-1 H₂SO₄ efficiently. The inhibition effects were investigated using the electrochemical impedance spectroscopy(EIS).EIS demonstrated that the charge-transfer resistance of the electrode covered with TEP film was greater than that of the naked iron electrodes and the inhibition efficiency of TEP film increased quickly in the initial period and then increased slowly. Quantum chemical calculations provide information about the process of adsorption of molecules on the metal surface at the molecular level.

Corrosion Inhibition Of Self-Assembled Films On Iron By Electrochemical Impedance Spectroscopy, Yuan-Yuan Feng, Shen-Hao Chen, Juan-Juan Zhou, Wen-Juan Guo

Journal of Electrochemistry

The self-assembled films of tetradecylamine were formed on iron surface, and the inhibition ability of which for iron corrosion in 0.5 mol/L H₂SO₄ solutions was studied by electrochemical impedance spectroscopy technique. Results indicated that longer immersion time would result in stronger inhibition ability of the films. The maximal inhibition efficiency(IE) of the tetradecylamine films was 68.7%. When the tetradecylamine films were modified by dodecylthiol, the mixed films became denser and more stable, thus the inhibition ability increased remarkably. The η of the mixed films increased to 78.2%.

Direct Electrochemistry Of Hemoglobin On The Electrode Modified With Ddab And Swcnt, Wen-Jing Hou, Lin Zhou, Xia-Qin Wu, Hong-Xia Zhang, Wen Xie, Liu Yang, Zhong-Qing Lu

Journal of Electrochemistry

Hemoglobin(Hb) was immobilized onto the surface of glassy carbon electrode with the single-wall carbon nanotubes and surfactant didodecyldimethylamonium bromide(DDAB) modified previously and its electrochemical behaviors have been investigated by cyclic voltammetry.A pair of well-defined redox peaks has been obtained.Cyclic voltammetry and electrochemical impedance spectroscopy(EIS) were also used to study on the effect of different concentration of SWCNT in DDAB.The result shows that the 1 mg/mL is the best choice.The dependence of E₀' on solution pH with the slope of 39 mV/pH,indicated that redox of the Hb is a one electron reaction with two protons transfer.The results also showed …

Design And Fabrication Of The High Efficient Platinum-Nanoporous Gold Catalysts, Zhao-Na Liu, Jin-Tao Zhang, Fang Tian, Peng-Peng Liu, Hou-Yi Ma, Yi Ding

Journal of Electrochemistry

The nanoporous gold(NPG) electrodes with uniform pore sizes and ligaments were prepared by using a simple dealloying method.The as-prepared NPG showed high catalytic activity towards the oxidation of formic acid and formaldehyde.After tiny amount of platinum was deposited onto the NPG substrate,not only the structure stability of NPG was greatly improved,but also the Pt-Au bimetallic catalysts displayed the better catalytic activity and the stronger poison resistance towards the electrooxidation of small organic molecules than the bulk platinum due to synergistic effect between Au and Pt compositions.

Electrochemical Synthesis, Characterization And Fluorescence Property Of Nano Na2Sif6, Guo-Xu Qin, Xin-Jun Wan, Xi-Mei Yuan, Dao-Bao Chu

Journal of Electrochemistry

The nano TiO₂ film was prepared by sol-gel process and characterized with X-ray diffraction(XRD) and scanning electron microscope(SEM).It was found that the average size of pore diameter was about 80 nm for the nano TiO₂ film.The Nano Na₂SiF₆ was synthesized by electrochemical deposition on the nanoporous film electrode and characterized with XRD and transmission electron microscope(TEM).The result showed that the average size of nanoparticle was 20 nm for the nano Na₂SiF₆.The fluorescence property of nano Na₂SiF₆ was also studied briefly.The result indicated that the nano Na₂SiF …

Electricity Generation In Microbial Fuel Cells Catalyzed By Mixed Culture And Pure Culture, Chen-Dong Shuang, En-Ren Zhang, Guo-Wang Diao, Fang-Fang Fan, Jie Yuan

Journal of Electrochemistry

Microbial fuel cells(MFCs) were constructed by inoculating fresh sedimentary microorganisms.Effect of phenol on performance of MFCs was investigated.The results showed that the generation of electrical current was induced by bacteria attached on the surface of the anode.Presence of phenol reduced the rate of glucose consumption and extended the duration of electricity generation with the same addition of glucose.In addition,the electricity generation by a single strain(belonging to pseudomonas species) separated from the sedimentary MFC was also investigated.The experimental results indicated that the presence of metabolic intermediates which exhibited electrochemical activity was necessary for the electricity production.Analysis of GC-MS showed that the …

Sucrose Modification On Li4Ti5O12 Anode Material, Zhi-Hong Tian, Hai-Lei Zhao, Zhi-Feng Wang, Jie Wang

Journal of Electrochemistry

The carbon modified Li4Ti5O12 was prepared by solid state reaction by using sucrose as carbon source. The XRD results showed that the incorporation of carbon did not change the spinel crystal structure of Li4Ti5O12 but it could prevent the particle agglomeration. The sample with 10%(by mass) sucrose displayed the best electrical performance, a 179.1 mAh/g of initial specific capacity was obtained at 0.2C, while 143.8 and 129.4 mAh/g at 2C and 3C, respectively. The CV and EIS studies revealed that carbon modification lowered the electrode polarization and electrode reaction resistance of Li4Ti5O12.

Preparation And Supercapacitive Properties Of Co(Oh)2/Nay Composite, Chi Ma, Ling-Bin Kong, Yong-Chun Luo, Long Kang

Journal of Electrochemistry

The Co(OH)₂/NaY composite was prepared by chemical precipitation method and then tested as an active electrode material for an electrochemical supercapacitor.The results indicated that the composite displayed superior capacitive performance.The maximum specific capacitance of Co(OH)₂ was 632.5 F/g.The structure and electrochemical properties of the composite were also discussed.

Electrochemical Properties Of Sub-Micron Li4Ti5O12 Powders, Chen-Shu Du, Hua-Bin Yang, Zuo-Xiang Zhou, Meng-Tao Wu, Lai-He Huang, Ning Xu

Journal of Electrochemistry

The sub-micronmeteric Li4Ti5O12 powder material was successfully prepared through an improved solid-state synthesis process.The results of X-ray diffraction(XRD), scanning electron microscopy(SEM) and laser particle size distribution analysis showed that only a single spinel phase and a normal distribution pattern with the average size(D50) of 0.886μm could be observed. Due to the suitable partical size distribution, the Li4Ti5O12 powders showed a promising electrochemical performance. At the discharge current densities of 0.1C(16.5 mAh/g) and 5C, the discharge capacities reached 165 mAh/g and 107 mAh/g, respectively. Even at 10C, it still reached 54 mAh/g.

Formation Of Copper Microcrystals On Porous Silicon Films, Lan-Li Chen, Fu-Fang Zhou, Bao-Gai Zhai, Yuan-Ming Huang

Journal of Electrochemistry

Microcrystals of metallic copper were electrochemically deposited onto the surface of porous silicon films in the aqueous electrolyte of copper(II) chloride.The microstructures of electrochemically deposited copper microcrystals on the porous silicon films were characterized by using scanning electron microscopy.The results have demonstrated that both center-hollowed and center-solid equilateral triangles in the sizes of several micrometers can be formed on the smooth bed of copper microcrystals.As the deposition duration increased from 0 to 28 hours,the fractal dimensions of the porous silicon was decreased from 2.608 to 2.252,suggesting that the electrochemical deposition can smooth the rough surface of porous silicon films.Compared to …

Micro-Algae Could Play A Significant Role In Achieving Energy Independence, Thomas Nartker

UNLV Renewable Energy Symposium

The 2008 UNLV Renewable Energy Symposium was presented by the Office of Strategic Energy Programs and co-sponsored by the Division of Research and Graduate Studies on August 20, 2008 on the UNLV campus.

The event focused on renewable energy production in Nevada, the US Southwest, and renewable research projects nationwide. It was a great opportunity for anyone working on renewable projects to collaborate with others in this field and exchange information. Over 230 individuals attended the event this year.

New Functional Polymers For Alternative Energy Applications, Chulsung Bae

UNLV Renewable Energy Symposium

The 2008 UNLV Renewable Energy Symposium was presented by the Office of Strategic Energy Programs and co-sponsored by the Division of Research and Graduate Studies on August 20, 2008 on the UNLV campus.

The event focused on renewable energy production in Nevada, the US Southwest, and renewable research projects nationwide. It was a great opportunity for anyone working on renewable projects to collaborate with others in this field and exchange information. Over 230 individuals attended the event this year.

Hydrogen Fuel Cells And Storage Technology (Fcast) Project, Clemens Heske

UNLV Renewable Energy Symposium

The 2008 UNLV Renewable Energy Symposium was presented by the Office of Strategic Energy Programs and co-sponsored by the Division of Research and Graduate Studies on August 20, 2008 on the UNLV campus.

The event focused on renewable energy production in Nevada, the US Southwest, and renewable research projects nationwide. It was a great opportunity for anyone working on renewable projects to collaborate with others in this field and exchange information. Over 230 individuals attended the event this year.

Solar Thermochemical Hydrogen Production Project – Progress Toward Industrial Scale Water Splitting, Roger Rennels

UNLV Renewable Energy Symposium

The 2008 UNLV Renewable Energy Symposium was presented by the Office of Strategic Energy Programs and co-sponsored by the Division of Research and Graduate Studies on August 20, 2008 on the UNLV campus.

The event focused on renewable energy production in Nevada, the US Southwest, and renewable research projects nationwide. It was a great opportunity for anyone working on renewable projects to collaborate with others in this field and exchange information. Over 230 individuals attended the event this year.

Experimentally Determining The Exchange Parameters Of Quasi-Two-Dimensional Heisenberg Magnets, P A. Goddard, J Singleton, P Sengupta, R D. Mcdonald, T Lancaster, S J. Blundell, F L. Pratt, S Cox, N Harrison, Jamie L. Manson, H I. Southerland, J A. Schlueter

Chemistry and Biochemistry Faculty Publications

Though long-range magnetic order cannot occur at temperatures T > 0 in a perfect two-dimensional ( 2D) Heisenberg magnet, real quasi-2D materials will invariably possess nonzero inter-plane coupling J(perpendicular to) driving the system to order at elevated temperatures. This process can be studied using quantum Monte Carlo calculations. However, it is difficult to test the results of these calculations experimentally since for highly anisotropic materials in which the in-plane coupling is comparable with attainable magnetic fields J(perpendicular to) is necessarily very small and inaccessible directly. In addition, because of the large anisotropy, the Neel temperatures are low and difficult to determine …

The Role Of Metal Coordnation In The Inhibition Of Iron(Ii)- And Copper(I)-Mediated Dna Damage By Organoselenium And Organosulfur Compounds, Erin Battin

All Dissertations

Copper and iron are two widely-studied transition metals associated with hydroxyl radical (OH) generation: Fe2+/Cu+ + H2O2 = Fe3+/Cu2+ + OH + OH-. Metal-mediated oxidative damage is a major cause of cellular DNA damage and death, and has been implicated in cancer, neurodegenerative, and cardiovascular diseases. Because sulfur and selenium antioxidants ameliorate oxidative damage, the ability of twenty biological sulfur- and selenium-containing compounds to inhibit metal-mediated DNA damage caused by hydroxyl radical has been quantified. In the Cu+/H2O2 system, six sulfur compounds and three selenium compounds inhibited DNA damage with IC50 values ranging from 3.3 to 25.5 μM. Several sulfur …