Physical Sciences and Mathematics Commons^™

The Study On Fabricating Thin Electrodes For Polymer Electrolyte Membrane Fuel Cells(Pemfc), Yong-Sheng Yang, Jing-Hua Liu, Chang-Peng Liu, Gong-Quan Sun, Chang-Zhi Li, Tian-Hong Lu

Journal of Electrochemistry

To lower platinum loading in electrodes for polymer electrolyte membrane fuel cell,a new thin electrode fabrication technique(TEFT) was developed in this work.A series of low Pt loading electrodes with smooth and uniformed surface were fabricated by the TEFT.As a result,the maximum power density of the cell with platinum loading of 1 mg/cm 2 and Nafion 117 membrane as electrolyte was up to 0.3 W.cm -2 .Moreover,the effects of PTFE and Nafion content in cathodes on the performance of PEMFC with low Pt loading electrodes(1 mg Pt/cm 2)were examined systematically.

Microsystem And Electrochemistry, Zhong_Qun Tian, Jian-Jun Sun

Journal of Electrochemistry

Microsystem or micro electromechanical system (MEMS) is briefly introduced. The electrochemical applications in microsystem are reviewed and prospective applications of microsystem in electrochemistry are discussed. Along with the rapid development of micro_ analytical chemical systems or lab_on_chips in 21st century, electrochemistry may play an increasingly important role in microsystem technology.

Effect Of Different Species Of Cobalt Additive On Performance Of Nickel Hydroxide Electrode, Xian-Xia Yuan, Yin-Dong Wang, Feng Zhan

Journal of Electrochemistry

Performances of nickel electrodes when adding or without adding Cobalt in different forms were studied, the results were interpreted by cyclic voltammetry(CV)and electrochemical impedance spectroscope(EIS). It was demonstrated that the additions of Co,CoO,CoO+Co by mechanically mixing with Ni(OH) 2 all can improve the performance of nickel electrode to some extent,and when Co is added in the form of CoO the best performance can be obtained. This can be mainly attributed to the fact that three kinds of Co additives all improved the structure of nickel hydroxide and the ability of H + in electrolyte transporting through the material,hence the reversibility …

Determination Of Diclofenac In Voltalin Tablets By Differential Pulse Voltammetry, Gui-Fen Wang, Yuan-Zhe Piao

Journal of Electrochemistry

Diclofenac,dissolved in a base solution of chlorhydric acid,showed a sensitive oxidation peak at 0.91 V(vs.SCE) when the solution was cyclically swept from +0.6 to +1 2 V(vs.SCE) by differential pulse voltammetry at GCE.There was a good linear relationship between the differential pulse peak current and the concentraion of diclofenac in the range from 5.0×10 -7 to 6.0×10 -6 mol/L,and the relative standard deviation is 3.5%(n=10).When determining the content of diclofenac in voltalin tablets, we have got the same results by this method as ultraviolet spectrophotometry.

Studies On Electrochemical Synthesis Of 4,5-Disubstituted-1,2- Benzoquinones And The Reaction Mechanism, Xian-Zhang Bu, Gui-Wu Xiao, Lin Ma, Xing-Chum He, Ling-Quan Gu

Journal of Electrochemistry

The oxidation peak potentials( E p) of alinine derivates and catechol in 0.1 mol/L KCl+15% alcohol solution were measured by cyclic voltammograms technique. The electrochemical oxidation condition was set according to the E p. Three derivates of 4,5_disubstituted _1,2_benzoquinones were prepared via electrochemical oxidation_Michael addition reaction. The possible mechanism of electrochemical oxidation_Michael addition reaction is presented.

Studies Of The Preparation Of Electrodes From Lead Carbonate For Lead-Acid Battery Ⅱ.The Preparation Of Paste Electrodes, Zhong-Xu Dai, Di-Hua Wang, Hao-Hao Ke, Jin-Yun Zou, Yun-Hong Zhou

Journal of Electrochemistry

The positive and negative pastes were prepared by mixing PbCO 3 and H 2SO 4 solution as well as relative additives, respectively. The effects of the various formation methods and the charge/discharge conditions on discharge capacity and active material utilization of both electrodes were examined. The results indicate that the performance of the positive electrode formed at 2.0 mA/cm 2 is better than that formed at higher current density under the same charge/discharge condition, the PAM utilization reaches 74.4 % under discharging at 2.0 mA/cm 2; and the property of the negative electrode formed by unsymmetrical square wave is superior …

In-Situ Simultaneous Esr And Conductivity Measurements For Polyaniline, Lin Zhuang, Qing Zhou, Jun-Tao Lu

Journal of Electrochemistry

With a new cell design, simultaneous electrochemical ESR and conductance measurements were realized for the first time. The in_situ cell consisted of a dual working electrode, a counter electrode and a reference electrode accommodated in a capillary of 1mm diameter. The dual working electrode was composed of two closely spaced Pt electrodes: a Pt disk electrode(0.5 mm diameter)sealed in a thin glass tube and a Pt layer deposited on the outside wall of the glass tube.The two working electrodes were separated by the glass gap about 20 μm thick. Two potentiostats were used to control electrode potential and maintain 10 …

Inhibition Of N,N'-O-Phenylen-Bis(3-Methoxysalicylidenimine) On Copper In Halide Solutions, Hou-Yi Ma, Shen-Hao Chen, Zhen-Lan Quan, Lin Niu, Shu-Lan Li

Journal of Electrochemistry

Inhibition of N,N'_o_phenylen_bis(3_methoxysalicylidenimine)(V_o_Ph_V)on corrosion and anodic disslution of copper in neutral NaCl and NaBr solutions was investigated in terms of potentiostatic steady_state polarization and A.C. impedance techniques.The inhibition mechanism of V_o_Ph_V to copper corrosion was interpreted in detail by comparing the electrochemical behaviors of copper in halide solutions with or without V_o_Ph_V. Besides,the inhibition effect of self_assembled V_o_Ph_V film on copper corrosion in NaCl was also studied.

Study On Preparation Of Coarse And Fine Γ-Lialo_2 Mixed Powder Used For Mcfc Matrix, Hua-Xin Lin, Bao-Lian Yi, Lian-Ying Kong, En-Jun Zhang, Li Zhou, Feng-Xia Wang

Journal of Electrochemistry

Coarse α_LiALO 2 powder was transferred completely to γ_LiAlO 2 at 900 ℃ for ten hours.Fine γ_LiAlO 2 powder was prepared by “chloride” synthesis. MCFC matrix was fabricated by mixing the coarse and fine γ_LiAlO 2 powder and by tape cast.The out'put voltage of the cell assembled with the matrix was 0.85 and 0.75 V respectively at 200 and 300 mA/cm 2,and power density was about 250 mW/cm 2.The performance of the matrix fabricated with the mixed powder was obviously more advanced than that of the matrix fabricated with only coarse γ_LiAlO 2 powder.

Electrochemical Characterization Of Ir-Ta-Ti Metal Oxide Coated Titanium Anodes, Ting-Yong Wang, Li-Kun Xu, Guang-Zhang Chen

Journal of Electrochemistry

Ir_Ta_Ti metal oxide coated titanium anodes of variable composition were prepared by thermal decomposition. Their micro morphorogies and electrochemical properties were characterized by scanning electron microscope, open circuit potential, cyclic voltammetry, consumption rate measurements and accelerated life test. The SEM results indicated that all coatings were of a porous and cracked_mud microstructure influenced greatly by the composition of coatings. The electrochemical measurements showed that the Ir_Ta_Ti ternary oxide_coated anodes exhibited excellent electrochemical activity and electrochemical stability in both acidic media and seawater which were affected by the composition and microstructure of the coatings. Owing to good corrosion resistance and low …

Fabrication And Examination Of Reduced Temperatrue Solid Oxide Fuel Cell Using A Supported Thin Ysz Electrolyte Substrate, Yi-Huang Zhang, Yong-Lei Dong, Yi Jiang, Zhi-Gui Lu, Jing-Wang Yan

Journal of Electrochemistry

By using a cost_effective wet process,dense yttria stabilized zirconia (YSZ) films on Ni_YSZ anode substrates have been prepared successfully.The YSZ film was characterized to be around 10 μm in thickness,sufficiently dense,uniform and crack free.A single solid oxide fuel cell fabricated from the supported YSZ film electrolyte on the anode substrate and a LSM cathode prepared on the YSZ film was tested.The power density reached to 0.1 W/cm 2 at 800 ℃,showing a reasonable performance.Further analysis on both electrodes shows that the anodic overpotential was much larger than IR drop (including YSZ resistance and contact resistance) and than the cathodic overpotential.The …

Cathodic Indirect Electro-Oxidation——Organic Electro-Synthesis Dimethyl Sulfone, Deng-Ping Gu, Rui-Zhi Wang, Hong-Kun Zhang, Xue-Ying Zhang, Wei Li

Journal of Electrochemistry

A cathodic indirect electro_oxidation system was established for indirect electro_oxidize dimethyl sulfoxide to dimethyl sulfone with electro_reduction generated H 2O 2 catalyzed by the pertungstate/tungstate(WO 5 2- /WO 4 2- )redox mediator. Influences of current density,pH,temperature,and the current efficiencies etc. on the cathodic indirect electro_oxidation of dimethyl sulfone were investigated for determining optimum reaction conditions.The current efficiency reached more than 70%.Mother_liquid could be recycled to use without pollution.

An Eis Study On The Synergetic Filming Between Cathodic Protection And The Corrosion Inhibitor, Yong-Tao Zhao, Jian-Hua Wu, Jian-Hua Qian, Hui Yu

Journal of Electrochemistry

The electrochemical impedance spectroscope(EIS) of 907A steel in seawater was investigated to study the film formation and destruction. The corrosion protection mechanism of the synergy interaction between cathodic protection and YKI_5 corrosion inhibitor(a mixture of polyhydric alcohol phosphate ester, phosphate and polyphosphate) is discused. Typical EIS spectral changes were clearly observed during the film formation and destruction processes. EIS results indicated that the film seemed to formed a multi_layered structure which consist of an inner layer(this may be an inhibitor_metal complex layer) and many outer layers of calcareous deposits. The film possesses of good persistency under the testing conditions.

Deposition And Characterization Of Electroless Nickel-Phosphorus-Boron Coatings From Acidic Bath, Tai-Xiang Jiang, Hui-Huang Wu

Journal of Electrochemistry

Acknowledgments The authors gratefully acknowledge Professor B.W.Mao for use of AFM facilities at her laboratory. We would also like to thank J.Tang for assistance with AFM measurements.

Study On Oxygenation Of Histidion-Cobalt And Monoiodohistidine-Cobalt Complexes By Cyclic Voltammtry, Yi Zhang, Ji-De Wang, Fan Yue, Xiao-Gang Zhang, Qi-Jun Song

Journal of Electrochemistry

The oxygenation of Histidine_Co and Monoiodohistidine_Co complexes were studied by cyclic valtammtry under certain conditions,The possibility of studing the oxygenation processes by cyclic voltammetry method was proposed and discussed in comparison with the results of potentiometry and spectrophotometry.

Investigations Of Lithium Ion Battery Electrolyte Solution, Jing-Li Han, Qing-Guo Liu

Journal of Electrochemistry

Synthesis and electrochemical investigations of ｛LiB[(SO 3)C 6H 3(O)(COO)]OC 6H 5｝in EC/DMC or DMSO/PC mixtures are presented.

High-Performance Liquid Chromatographic Separation Of The Enantiomers Of Unusual Α-Amino Acid Analogues, Antal Péter, Edit Olajos, Richard Casimir, Dirk Tourwé, Quirinus B. Broxterman, Bernard Kaptein, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

The direct and indirect stereochemical resolution of the enantiomers of ring- and α-methyl-substituted phenylalanines and phenylalanine amides was attempted by high-performance liquid chromatographic methods. The direct separation was carried out on two chiral stationary phases, the crown-ether- based Crownpak CR (+), and the teicoplanin-based Chirobiotic T, while the indirect resolution was performed by applying pre-column derivatization with 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate (GITC) and Nα- (2,4-dinitro-5-fluorophenyl)-L-alanine amide (Marfey's reagent, FDAA). The Chirobiotic T column was efficient in the separation of ring- and α-methyl- substituted phenylalanine analogues but was ineffective for the amides of these analogues. The Crownpak CR (+) column separated the ring-substituted …

Hydrogen Bonding In Alcohol Clusters: A Comparative Study By Infrared Cavity Ringdown Laser Absorption Spectroscopy, Robert A. Provencal, Raphael N. Casaes, Katja Roth, Joshua B. Paul, Chris N. Chapo, Richard J. Saykally, Gregory S. Tschumper, Henry F. Schaefer

Chemistry Faculty Research & Creative Works

Infrared cavity ringdown laser absorption spectroscopy has been used to study the O-H stretching vibrations of jet-cooled ethanol and butanol clusters. Three bonded O-H stretches were attributed to the ethanol dimer, indicating the presence of more than one conformer in the molecular beam. One unresolved feature was measured for both the trimer and tetramer. To facilitate spectral assignment, the vibrational frequencies and intensities have been calculated for the ethanol dimer using second-order Moller-Plesset perturbation theory. Three bonded O-H stretches have also been measured for the butanol dimer, suggesting that more than one conformer is present in the molecular beam. Vibrational …

Quantum Calculations On The Vibrational Predissociation Of Nebr2: Evidence For Continuum Resonances, Thomas Alex Stephenson, N. Halberstadt

Chemistry & Biochemistry Faculty Works

Quantum mechanical calculations on the vibrational predissociation dynamics of NeBr2 in the B electronic state have been performed and the results compared with both experimental data and other computational studies. For vibrational levels with v less than or equal to 20 we find that the vibrational state dependence of the predissociation lifetimes is in qualitative agreement with experimental measurements, as are the calculated Br-2 fragment rotational distributions. For higher vibrational levels, the B <-- X excitation profiles are well represented by a sum of two Lorentzian line shapes. We attribute this result to the presence of long-lived resonances in the dissociative continuum that are reminiscent of long-lived dissociative trajectories in previous classical studies of NeBr2. (C) 2000 American Institute of Physics. [S0021-9606(00)00205-1].

Degradation Of N-Hexadecane And Its Metabolites By Pseudomonas Aeruginosa Under Microaerobic And Anaerobic Denitrifying Conditions, Chawala Chayabutra, Lu-Kwang Ju

Chemical, Biomolecular, and Corrosion Engineering Faculty Research

A strategy for sequential hydrocarbon bioremediation is proposed. The initial O-2-requiring transformation is effected by aerobic resting cells, thus avoiding a high oxygen demand. The oxygenated metabolites can then be degraded even under anaerobic conditions when supplemented with a highly water-soluble alternative electron acceptor, such as nitrate. To develop the new strategy, some phenomena were studied by examining Pseudomonas aeruginosa fermentation. The effects of dissolved oxygen (DO) concentration on n-hexadecane biodegradation were investigated first. Under microaerobic conditions, the denitrification rate decreased as the DO concentration decreased, implying that the O-2-requiring reactions were rate limiting. The effects of different nitrate and …

Observations Of Particulates Within The North Atlantic Flight Corridor: Polinat 2, September-October 1997, J. D. Paladino, Donald E. Hagen, Philip D. Whitefield, Alfred Raymond Hopkins, Otmar Schmid, M. R. Wilson, Hans Schlager, Peter Schulte

Physics Faculty Research & Creative Works

This paper discusses particulate concentration and size distribution data gathered using the University of Missouri-Rolla Mobile Aerosol Sampling System (UMR-MASS), and used to investigate the southern extent of the eastern end of the North Atlantic Flight Corridor (NAFC) during project Pollution From Aircraft Emissions in the North Atlantic Flight Corridor/Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (POLINAT 2/SONEX) from September 19 to October 23, 1997. The analysis presented in this paper focuses on "the corridor effect," or enhancement of pollutants by jet aircraft combustion events. To investigate the phenomena, both vertical and horizontal profiles of the corridor, and regions …

Lifetime Effects On The Dissociation Of Core-Excited N2 And Co Molecules, N. Saito, A. Hempelmann, F. Heiserq, Oliver Hemmers, K. Wieliczek, J. Viefhaus, U. Becker

Environmental Studies Faculty Publications

Vibrational-resolved ion and ion-pair yield spectra of N₂ and CO taken at their 1s⃗π^* resonance excitations reveal decay-channel-dependent core hole lifetimes. The linewidths of the yield spectra tend to be shortened when the number of electrons ejected in the deexcitation process increases, finally becoming narrower than the total ion yield or absorption natural lifetime width of the core-excited states of N₂ and CO, respectively. In contrast to this, the linewidths of the yield spectra for the singly charged molecular ions, N₂⁺ and CO⁺, are shown to be broader than their corresponding natural linewidths. …

9-Phenyl-3,4,4a,9a-Tetrahydrotriptycene And 9-Phenyl-1,2,3,4,4a,9a-Hexahydrotriptycene, John Masnovi, Shaoming Duan, Ronald J. Baker

Chemistry Faculty Publications

The structure of 9-phenyl-3,4,4a,9a-tetrahydrotriptycene, C26H22, (I), exhibits regiochemistry consistent with a stepwise mechanism for its formation from photocycloaddition of 1,3- cyclohexadiene and 9-phenylanthracene. Bond distances involving the bridgehead C atoms are similar in (I) and the hydrogenated derivative, 9-phenyl-1,2,3,4,4a,9a-hexahydrotriptycene, C26H24, (II), with bonds to the quaternary-C atoms exhibiting significant elongation [1.581 (2) A Ê in (I) and 1.585 (2) A Ê in (II)]. The molecular geometry precludes significant overlap between the phenyl groups and the interannular bonds in both compounds, indicating that the origin of the bond lengthening is steric in nature.

Characterizing The Structure Of Polyimide Model Compounds At Metallic Interfaces, Mark Anderson

Mark R. Anderson

No abstract is available at this time.

Surface Composition Of MnXCo1-XO Solid Solutions By X-Ray Photoelectron And Auger Spectroscopies, Marjorie Langell, F. Gevrey, M. W. Nydegger

Marjorie A. Langell Publications

Auger and X-ray photoelectron spectroscopies have been used to study the surface composition of Mn_xCo_1-xO (0 ≤ x ≤ 1) solid solutions. The polycrystalline materials, which are bulk homogeneous, present clear signs of deviation in surface composition at x_bulk ≈ 0.2–0.4 to become surface-enriched in manganese at the expense of the cobalt. Whether on stoichiometric or cobalt-depleted surfaces, cobalt retains the characteristic XPS 2p satellite structure and binding energies of the rock salt monoxide (CoO or Mn_xCo_1-xO) environment. Manganese 2p XP spectra are appropriately monoxide-like for the stoichiometric surfaces …

Octafluoro-Meso Tetraarylporphyrins And Methods For Making These Compounds, Stephen G. Dimagno

Chemistry Department: Faculty Publications

The novel compounds of the present invention are f-octafluoro-meso-tetraarylporphyrins of formula (I) and their metallic complexes of formula (II):

B-octafluoro-meso-tetraaryl porphyrins are Synthesized by reacting 3,4-difluoropyrrole with an aromatic aldehyde in the presence of boron trifluoride etherate, followed by oxidation. The difluoropyrrole used in this reaction is pro duced by reacting 3,3,4,4-tetrafluoropyrroline or its corre sponding Salt, 3,3,4,4-tetrafluoropyrrolidinium Salt, with a base Such as potassium tert-butoxide. The metalloporphyrins of the present invention are Synthesized by deprontonating B-octafluoro-meso-tetraarylporphyrin ligands and treating Said ligands with metal ions.

Surface Effects On The Dynamics Of Liquid Crystalline Thin Films Confined In Nanoscale Cavities, Alison Noble, Ralph G. Nuzzo, Renée M. Blanchard

Educator Scholarship

The dynamics of 4-n-pentyl-4'-cyanobiphenyl (5CB) nematic liquid crystalline thin films have been studied in real time using step-scan Fourier transform infrared spectroscopy (FTIR). In these studies, the liquid crystal was confined in a nanocavity defined and bounded by an interdigitated gold electrode array. The gold microstructures were microfabricated on a zinc selenide (IR-transparent) window. The 5CB interactions with the ZnSe substrate result in surface-induced ordering of the ultrathin layers (on the order of 40 nm). As the films increase in thickness, the nanoscale organization induced by the surface layer becomes a less significant contributor to the overall bulk structure of …

Atomization Enthalpies And Enthalpies Of Formation Of The Germanium Clusters, Ge5, Ge6, Ge7, And Ge8 By Knudsen Effusion Mass Spectrometry, Karl A. Gingerich, R W. Schmude, M Sai Baba, Giovanni Meloni

Chemistry Faculty Publications

The high-temperature mass spectrometric method was employed to measure the equilibrium partial pressures of small germanium clusters above liquid germanium contained in a graphite Knudsen cell. These data were combined with new thermal functions, calculated from recent theoretical and spectroscopic molecular parameters, to evaluate the atomization enthalpies and enthalpies of formation of Ge[sub 5]-Ge[sub 8]. Mass spectrometric equilibrium data available in literature were also reevaluated. The following atomization enthalpies, Δ[sub a]H[sub 0][sup o](Ge[sub n],g) and enthalpies of formation Δ[sub f]H[sub 298.15][sup o](Ge[sub n],g), in kJ mol-1, have been obtained: Ge[sub 5], 1313±27 and 548±27, Ge[sub 6], 1649±33 and 583±33, Ge[sub …

Thermodynamic Stability Of Sn4, Sn5, Sn6, And Sn7 Clusters By Knudsen Cell Mass Spectrometry, Giovanni Meloni, R W. Schmude, J E. Kingcade, Karl A. Gingerich

Chemistry Faculty Publications

The Knudsen cell mass spectrometric method has been employed to measure the partial pressures of Sn[sub n] (n=1-7) under equilibrium conditions above liquid tin or a tin-gold alloy, contained in a graphite Knudsen cell. From the all-gas analyzed equilibria the following atomization enthalpies Δ[sub a]H[sub 0][sup °](Sn[sub n]), and enthalpies of formation, Δ[sub f]H[sub 298.15][sup °](Sn[sub n]), in kJ mol-1, have been obtained: Sn[sub 4], 750.2±14 and 450.6±14; Sn[sub 5], 990.2±22 and 512.3±22; Sn[sub 6], 1349.7±28 and 452.8±28; Sn[sub 7], 1644.2±37 and 460.0±37. The atomization energies are compared with available …

Knudsen Cell Mass Spectrometric Investigation Of The B2n Molecule, Giovanni Meloni, M Sai Baba, Karl A. Gingerich

Chemistry Faculty Publications

High-temperature Knudsen cell mass spectrometry has been used to study the equilibria involving the B2Nmolecule over the Si–BN system. Thermal functions needed in the evaluation of the mass spectrometric equilibrium data have been calculated from available experimental and theoretical molecular parameters. The enthalpy changes for the reactions2B(g)+Si2N(g)=B2N(g)+2Si(g),and BN(s)+B(g)=B2N(g)have been measured. The following atomization enthalpy,ΔaHo0,and enthalpy of formation,ΔfHo298.15,in kJ mol⁻¹, of1045.5±18 and551.3±18 for theB2N molecule have been determined from these reactionenthalpies. Atomization energies of similar molecules have been compared and discussed.