bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutral Surfactants Removal Kinetic from Sodium Chloride Solution by Galvanochemical Process
Authors: Pikelny Aleksandr , Pikelnaya Olga
Published: November 2006

Galvanochemical (galvanocoagulation) process of water treatment based on use of metals corrosion. This process especially effective for treatment of low concentrated solutions containing wide range admixtures of various natures. Here we present results of investigation on rates of neutral surfactants removal from sodium chloride solutions, correlated with kinetics of carbon steel corrosion and ferrous/ferric hydroxides forming. We also discuss and compare mathematical models that were created in order to describe galvanochemical process.
Whisker Formation in Pb-Free Surface Finishes
Authors: Stafford Gery , Williams Maureen , Johnson Christian , Moon Kil-Won , Boettinger William , Bertocci Ugo , Kongstein Ole
Published: November 2006

High purity bright Sn, Sn-Cu and Sn-Pb layers measuring 3, 7 and 16 μm thick were electrodeposited onto phosphor bronze cantilever beams in a rotating disk apparatus. Beam deflection measurements within 15 min of plating proved that all electrodeposits had in-plane compressive stress. In several days, the surfaces of the Sn-Cu deposits, which have the highest compressive stress, develop 50 μm contorted hillocks and 200 μm whiskers, pure Sn deposits develop 20 μm compact conical hillocks, and Sn-Pb deposits, which have the lowest compressive stress, remain unchanged. Over longer time, analysis of beam deflection measurements indicates that the compressive stress is augmented by the formation of Cu6Sn5 on the bronze/Sn interface, while creep of the electrodeposit tends to decrease the compressive stress. Uniform creep occurs for Sn-Pb because it has an equi-axed grain structure. Localized creep in the form of hillocks and whiskers occurs for Sn and Sn-Cu because both have columnar structures.
Electrodeposition of Copper-Manganese Alloy Coatings for Sacrificial Corrosion Protection
Authors: Gong Jie , Zangari G.
Published: November 2006

Electrodeposited Mn alloys are studied as potential replacements to Cd sacrificial coatings. Two types of sound manganese coatings, crystalline and amorphous, can be electrodeposited from an ammonium sulfate electrolyte. Crystalline Mn coatings are chemically reactive and their crystal structure is unstable, resulting in brittle coatings. In order to improve the corrosion resistance of Mn coatings, Sn-Mn codeposition was studied, with or without addition of citrate, tartrate, EDTA or gluconate additives. The addition of tartrate, EDTA and gluconate can improve the coating appearance and microstructure. Sn-Mn coatings show an improved and tunable corrosion resistance, maximized when intermetallic structures are predominant. Cu-Mn coatings were electrodeposited for the purpose of stabilizing the ductile γ'- Mn phase. Cu-Mn coatings with appropriate composition combine stability of the ductile crystalline structure with the capability of forming a partially protective layer to slow down alloy corrosion. Cu-Mn alloy coatings have desirable mechanical and tribological properties, showing lower friction coefficient than reference Cd films. These materials may provide for drop-in replacement to Cd and deserve further investigation.
Electronic and Magnetic Properties of Carbon-Coated Lithium Iron Phosphates
Authors: Julien C. M. , Zaghib K. , Ait Salah Atmane , Mauger Alain , Gendron Francois
Published: November 2006

The electronic and magnetic properties of microcrystallite LiFePO4 prepared with and without carbon coating are analyzed using XRD, FTIR, Raman spectroscopy, and magnetic measurements, for comparison. While nano-sized ferromagnetic particles (gamma- Fe2O3) are evidenced from magnetic measurements in sample without carbon coating, such ferromagnetic clusters just do not exist in the carbon-coated sample. The carbon deposit belongs to the family of amorphous graphite deposit. It is a hydrogenated layer with very small H/C ratio having the properties of a-C films obtained by pyrolysis technique.
The Influence of Binders on the Performances of Ni(OH)2 Positive Electrode in Supercapacitor
Authors: Yu Weiping , Yang Xiaoping , Wang Pengpeng , Meng Lingkuan
Published: November 2006

The Polyvinyl alcohol (PVA), polytetrafluorethylene (PTFE) and styrene-butadiene-rubber (SBR) were co-deposited with Ni(OH)2 respectively to serve as positive electrodes. Well adherent Ni (OH)2 deposits with honeycomb and coral structures were obtained by doping PTFE and SBR to serve as active materials of the positive electrode. The effective surface area of active materials was significantly increased, so that specific capacitance of Ni(OH)2 positive electrode was enhanced as well. The measurement on capacitances of the assembled C/Ni(OH) 2 capacitors indicates that the capacitances of such Ni(OH)2 positive electrodes doped PTFE can reach 670F/g, 550 F/g,500 F/g and 380 F/g, while the capacitances of such Ni(OH)2 positive electrodes doped SBR can reach 710F/g, 667F/g, 539 F/g and 421 F/g, when they discharge at the current densities: 2 mA/cm2, 8 mA/cm2, 16 mA/cm2 and 32 mA/cm2 respectively.
Rotating Rate Dependency of Methanol Oxidation on a Smooth Polycrystalline Platinum Surface
Authors: Hou Guoyan , Prakash J.
Published: November 2006

Methanol adsorption and oxidation on platinum based catalysts have been extensively studied on well-characterized single crystal Pt, polycrystalline Pt, PtRu alloys, as well as high surface area catalysts. However, the quantitative kinetic and mechanistic studies using hydrodynamic techniques such as rotating disk electrode (RDE) or rotating ring-disk electrodes (RRDE) have been severely limited , , . The aim of this study was to examine the kinetics of methanol oxidation on a polycrystalline platinum rotating disc electrode in an acidic solution. The experiments were carried out in a conventional electrochemical cell. The electrolyte consisted of a solution of approximately 1M, de-oxygenated methanol and 0.5MH2SO4 at room temperature. The rotating disk electrode (RDE) measurements for the methanol oxidation on the Pt disk electrode were obtained at various rotation rates. Polarization curves obtained with the RDE measurements indicate that the kinetics and mechanism of the methanol oxidation are potential dependent. A mass transport corrected Tafel slope of 125 mV/decade was found on the relatively oxide free surface and is indicative of the first electron transfer as the rate determining step.
Ionic Liquid Based Electrolytes for High Energy Electrochemical Storage Devices
Authors: Passerini Stefano , Alessandrini Fabrizio , Appetecchi G. B. , Conte Mario
Published: November 2006

In the present work we report on the most recent development at ENEA on the synthesis and the characterization of Ionic Liquids for use as electrolytes or electrolyte components in lithium metal batteries and hybrid supercapacitors.
Direct Hydrothermal Processing of TiO2 Nanofibers from Natural Rutile Sand
Authors: Pavasupree Sorapong , Suzuki Yoshikazu , Yoshikawa Susumu , Kawahata Ryoji
Published: November 2006

Titanate nanofibers were synthesized by hydrothermal method (150 oC for 72 h) using natural rutile sand as the starting materials. TiO2 (B) and anatase TiO2 (high crystallinity) nanofibers with the diameters of 20-100 nm and the lengths of 10-100 μm were obtained by calcined titanate nanofibers for 4 h at 400 oC and 700 oC (in air), respectively. The samples characterized by XRD, SEM, TEM, SAED, HRTEM, and BET surface area. This synthesis method provides a simple route to fabricate one- dimensional nanostructured TiO2 from low cost material.
Electrical Field and Current Density Distribution Modeling of Aluminum Electrodeposition in Ionic Liquid Electrolytes
Authors: Zhang Mingming , Reddy Ramana
Published: November 2006

A mathematical modeling for predicting the electrical field and current density distribution of aluminum electrodeposition in ionic liquids was developed by assuming 2-D, steady state, binary electrolyte and constant properties. The model describes the deposition process by incorporating the mass transport of participating ionic species, homogeneous chemical reactions within the diffusion layer, and the associated electrochemical kinetics. The mixed mass transfer coefficient or rate constant of aluminum deposition were determined in the laboratory cell under controlled electrodeposition conditions, assuming that the mass transfer coefficient is independent of current density. The distribution of the electrical potential and current are discussed with emphasis on the influence of cell voltage and electrode distance. The results show the computed current densities are in good agreement with experimental data at applied cell voltage less than 3.5 V. Optimum electrode distance was determined to be 1.0-1.5 cm from electrical field distribution modeling.
Potential-dependent CO Adsorption On A Smooth Surface of Crystalline Pt By The Use of PEM-FTIR
Authors: Hou Guoyan , Smotkin Eugene
Published: November 2006

The potential-dependent CO adsorption in both H2 adsorption/desorption region and double layer region on polycrystalline platinum at room temperature and the oxidation of the adsorbed CO have been systemically studied. PEM-FTIR (Photon Elastic Modulation FTIR) technique along with cyclic voltammetry was used to understand the adsorption state and the mechanism of CO oxidation. In the hydrogen adsorption- desorption region of the smooth platinum surface, three types of adsorption states were observed for the CO adsorption. These states include a small portion of CO-I (Epeak =~0.75V), CO-II (Epeak=0.85~0.9V), and CO-III (Epeak=0.9V~0.95V). The CO stripping data suggest that the CO-I bonding state was kinetically least stable. In the double layer region, only CO- II or CO-III state was observed. In addition, the CO-III state was found to have much stronger bond with Pt. These results are in also in good agreement with the reported literature. The CO adsorbed in the hydrogen adsorption-desorption and double layer regions produced similar CO stretching frequency- potential slope of about 15 cm-1/V. An extended stark effect was observed for the CO adsorbed in the double layer region, indicating that CO adsorbed in double layer region is less subjected to the influence of dipole-dipole enhancement effect. The stark effect of CO adsorbed at different potentials may provide valuable information in understanding the CO oxidation mechanism.
Electroreduction of Complex Ions at Bismuth and Cadmium Single Crystal Plane Electrodes
Authors: Lust Enn , Nerut Jaak , Hark Eneli , Jager Rutha , Lust Karmen , Tahnas Kadri , Kallip Silvar , Thomberg Thomas , Grozovski Vitali
Published: November 2006

The electrical double layer structure and kinetics of electroreduction of the [Co(NH3)6]3+, [Fe(CN)6]3 and S2O82 ions on the electrochemically polished Cd(0001) and Bi(hkl) single crystals have been studied using in situ STM, impedance and rotating disc electrode methods. The large atomically flat surface areas have been observed on the electrochemically polished and cut Bi(111) electrode. The electroreduction data for [Co(NH3)6]3+ show that rate constant of the heterogeneous reaction depends on the crystallographic structure of the plane as well as on the base electrolyte used. The apparent transfer coefficient slightly higher than 0.5 indicates that there are only small deviations from the Frumkin slow discharge theory. The electroreduction of [Fe(CN)6]3 is limited mainly by the slow charge transfer step complicated by the adsorption of the reactants or reaction intermediates at the electrode in the region of current pits observed in the cyclic voltammograms obtained using the rotating disk electrode method.
Carbon Dioxide-Metal Carbonate Systems in Chemical Processes and Environmental Applications
Authors: Salminen Justin P. , Kobylin Petri
Published: November 2006

Carbonate minerals have always played an important role in the geochemistry of the Earth. Metal carbonates, like CaCO3, ZnCO3, PbCO3, and CdCO3 are sparingly soluble electrolytes. Carbon dioxide gas can be used to dissolve and precipitate metal carbonate M2+CO32- type salts from their chlorides utilizing CO2 weak acid character and common anion feature of the buffering electrolytes like NaHCO3. The thermodynamic analysis shows how speciation and solubilities change as a function of temperature, pressure, composition, and pH. For designing new chemical processes rigorous models and sound measurements are required to effect the ever-smaller input of chemicals, raw materials, and water. New industrial applications include treatment of waste- and process waters as well as recovering valuable or environmentally harmful metal ions as carbonates. Best available techniques and continuous improvements are needed to produce new environmentally acceptable, energy-efficient processes with lower CO2 emissions.
Koji Hashimoto: A Pioneer of Metastable Materials Science
Authors: Habazaki H. , Akiyama Eiji
Published: November 2006

The biography on the life and career of Professor Koji Hashimoto was written on the occasion of a special symposium of the Electrochemical Society, Inc. The symposium, entitled Corrosion and Electrochemistry of Advanced Materials, in Honor of Koji Hashimoto was held at the 208th Meeting of the Electrochemical Society in Los Angeles, CA, October 16-21, 2005.
Electrochemical Response of AA7075-T651 Following Immersion in NaCl Solution
Authors: Birbilis Nick , Buchheit Rudolph G , Cavanaugh Mary K
Published: November 2006

The electrochemical behavior of AA7075-T651 following immersion in quiescent 0.1M NaCl is presented. Electrochemical impedance at various polarization intervals was determined using Fourier transformation of potentiostatically induced current transients. This allowed for rapid determination of the impedance response at fixed intervals revealing a more detailed insight into the kinetic response of the alloy when assessed with complementary analysis tools such as potentiodynamic testing. This led to a discussion regarding aspects of dissolution phenomena prior to alloy breakdown and at short immersion times.
Injection of Hydrogen and Vacancy-Type Defects during Dissolution of Aluminum
Authors: Hebert K. R. , Adhikari Saikat , Lee Jinju , Chen Hongmin , Jean Y. C.
Published: November 2006

Formation of interfacial nanoscale voids in Al during room-temperature caustic corrosion was characterized by positron annihilation spectroscopy (PAS) and compared with measurements of deuterium absorption using secondary ion mass spectrometry (SIMS). The hypothesis was investigated that voids are created from vacancy-hydrogen (Vac-H) defects introduced during corrosion. Evidence for both mobile and immobile forms of absorbed hydrogen was obtained, the latter present within distances of 50 nm from the metal-oxide interface, where voids were also found. During corrosion, the immobile hydrogen was found only during discrete 1-2 min intervals of time separated by periods of 1-2 min when it was not present. Model calculations suggested that this transient behavior is consistent with repeated nucleation and dissolution of clusters of Vac-H defects. Only some aspects of the time-dependence of the void concentration from PAS corresponded with that of absorbed hydrogen; the former is believed to be influenced by metallic impurities.
Micromachining of Aluminum by Anodizing, Laser Irradiation, and Electrochemical Etching
Authors: Kikuchi Tatsuya , Takahashi Hideaki
Published: November 2006

Microgrooves were fabricated on aluminum surfaces using anodizing, laser irradiation, and electrochemical etching. Aluminum specimens covered with porous type oxide films were irradiated with a pulsed Nd-YAG laser in distilled water to remove the anodic oxide films locally. The subsequent electrochemical etching in CH3COOH / HClO4 solution made the grooves formed by the laser irradiation smoother. The width and the depth of the grooves increased with electrochemical etching time. Mesh-like micro-patterns with 70 µm width and 30 µm depth were fabricated on aluminum surfaces by consecutive processes of anodizing, laser irradiation, and electrochemical etching.
Corrosion Monitoring of Stainless Steels in Marine Atmospheric Environment
Authors: Nishikata Atsushi , Tsutsumi Yusuke , Tsuru Tooru
Published: November 2006

The rusting of Type 304 and 430 stainless steels due to occurrence of pitting corrosion has been monitored in marine and rural atmospheric environments using a remote-controlled AC impedance corrosion monitoring system. The monitoring results at the marine showed that the rusting of Type 304 progresses only under the relative humidity ranged from 35 to 75 %RH, while the rusting of Type 430 takes place all the relative humidity range over 35 %RH. The lower limit (35 %RH) corresponds to the relative humidity, above which water absorption of MgCl2 present in airborne salt starts. The upper limit (75 %RH) corresponds to the relative humidity in equilibrium with 6 M chloride solution. The concentration is identical with a critical chloride concentration of occurrence of pitting corrosion reported in the previous studies1-3). In the rural atmosphere, the monitoring results showed that both the stainless steels are always in passive state.
Structure of Steel Rusts with Good Atmospheric Corrosion Resistance
Authors: Nakayama Takenori , Tsubokawa Yoshiyuki , Ishikawa Tatsuo
Published: November 2006

The reduction of initial construction and maintenance costs of steel bridges requires better atmospheric corrosion resistance in chloride environments. The actual steel rusts obtained from accelerated exposure test and the artificial β-FeOOH rust with Ti were investigated mainly by transmission electron microscopy.Magnetite exists in laminate and β-FeOOH rust with a particle length of about 1 μm exists as matrix in mild steel. The β-FeOOH rust with a particle length of about 100 nm is mixed with magnetite fine crystals in Cu-Ni-Ti steel. Artificial Ti-doped β-FeOOH rust is much more fine compared with Ti-undoped rust.Ti remarkably impedes the crystallization and particle growth of β-FeOOH rust and that Ti addition controlled the size ofβ-FeOOH rust which is particularly in chlorideenvironments.
Corrosion Multi-Monitoring of Carbon Steel in Coastal Area
Authors: Katayama Hideki , Endou Masanori , Masuda Hiroyuki , Itagaki Masayuki , Watanabe Kunihiro
Published: November 2006

The corrosion behavior of carbon steel and the atmospheric corrosiveness were monitored simultaneously by the corrosion multi-monitoring system. The system consists of a temperature and humidity chamber, a corrosion monitor, an ACM data logger, a surface reaction measurement device and a microscope. After installing the corrosion sensor and the ACM sensor in the chamber, the droplet of artificial seawater with different chloride ion concentration was added to the sensor surface, and the relative humidity was changed from 30% to 95% in every 12 hours. As the relative humidity increased, both the corrosion rate and the ACM current increased and the surface potential shifted to less noble. Furthermore, the obtained data was discussed for the average thickness of electrolyte layer calculated thermodynamically. The corrosion behavior was divided into three regions for thickness of electrolyte layer, and the corrosion rate showed a maximum at a thickness of about 100μm.
Analytical Characterization of the Corrosion Mechanisms of WC-Co by Electrochemical Methods and Inductively-Coupled Plasma Mass Spectroscopy
Authors: Hochstrasser Sabine , Latkoczy Christopher , Virtanen Sannakaisa , Uggowitzer Peter , Schmutz Patrik
Published: November 2006

WC-Co exhibit a rather high susceptibility to corrosion in aqueous solutions, which is a result of complex reaction mechanisms. The local distribution of the surface reactions is thus of considerable interest. Electrochemical measurements provide only a one-sided information about the corrosion processes. For this purpose, comparative studies of elemental solution analysis by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) were carried out. The use of a flow cell allowed simultaneous online detection of dissolving elements. Surface characterization by XPS was used to determine the influence of solution contact on the surface composition. In order to elucidate the local aspects of the WC- Co corrosion behaviour, conventional electrochemical results (potentiodynamic polarization measurements) were compared to experiments, performed with a micro-capillary technique, which provides a focused view on the local corrosion situation. From these different methods, a more conclusive model presentation of the reaction mechanisms, taking place on WC-Co in aqueous solution, is proposed.
MO Simulation of Surface Diffusion of Zinc Adatoms on Zinc Surface
Authors: Azumi Kazuhisa , Iokibe Kei , Seo Masahiro
Published: November 2006

Surface diffusion process of zinc adatoms on zinc crystal surface was simulated using semi-empirical molecular orbital (MO) method. Total energy, ET, of molecular orbitals belong to the system including adatom and surface atoms was calculated for two surface models; one is a small cluster composed from surface atoms and another is periodically repeated arrangement of surface atoms. ET was calculated as a function of position of adatom on the terrace, near the step and kink sites to draw energy contour map. From the energy map migration path of adatom on the surface and their activation energy for diffusion, ED, were estimated. From these results adequacy of terrace-step-kink (TSK) model for epitaxial growth was confirmed. Formation of deposition island and effect of water molecular on the surface are also discussed.
Current Transients from Passive Iron Surface during Micro-indentation
Authors: Fushimi Koji , Takase Ken-Ichi , Azumi Kazuhisa , Seo Masahiro
Published: November 2006

Micro-indentation test of passive iron surface in pH 8.4 borate buffer solution was carried out to analyze current transients corresponding to the rupture and repair of passive film. During driving a conical diamond micro- indenter downward to the passive surface and driving upward from the surface, a couple of anodic current peaks were observed. The first current peak spiked during loading was responsible for partial exposure of iron substrate to the solution due to rupture of the passive film when the indenter tip deformed the substrate and penetrated. The second peak emerged during unloading when elastic deformation of the substrate recovered, which was ascribed to repair at the ruptured sites. The second peak current was larger than the first one. Both peaks were sensitively influenced by electrode potential or concentration of sulfate ions containing in solution. The model for a series of rupture and repair processes of the passive film by micro- indentation was proposed to discuss the current transients.
Detection of Currents from a Model Pit Using the Scanning Vibrating Electrode Technique
Authors: Sullivan James H. , Penney David , McMurray Neil , Worsley David
Published: November 2006

The scanning vibrating electrode technique (SVET) is a versatile technique for determining the location and intensity of anodes and cathodes and mechanisms in corroding systems. A model anode has been used to assess current profiles above such features in a variety of electrolytes and using various scanning parameters. The model anode has a current profile in between the theoretical determined results for equi-potential and equi-current discs. It has been shown that low concentration electrolytes (<0.1% NaCl) and low scan heights (<80 μm) are unsuitable for SVET testing.
Depassivation and Repassivation of Titanium under Particle Impingements
Authors: Akiyama Eiji , Tsuzaki Kaneaki
Published: November 2006

Current transients of a titanium microelectrode corresponding to an impingement of a single zirconia particle were measured in a buffer solution. It was found that the repassivation after a particle impact followed high field model of oxide growth. The apparent repassivation rate evaluated by the relation between the charge and the peak height of a current transient showed dependence on applied potential, and the apparent repassivation rate increased with increase of potential. The influence of potential applied passivation prior to particle impingement on the apparent repassivation rate was more predominant than that of the potential applied during impingement of relatively large particle. This indicates that the apparent repassivation rate does not represent the actual repassivation kinetics. It is suggested that the passive film formed prior to a particle impact and repassivation give rise to resistance against surface deformation and film breakdown, and that it affects the apparent repassivation behavior.
Chloride-Induced Pitting Corrosion of Iron in Mildly Alkaline Borate Buffer Solutions: Localized Dissolution Kinetics
Authors: Soltis Jozef , Hodges Steve , White Stephen , Cook Anthony , Laycock Nick
Published: November 2006

Chloride-induced pitting corrosion of pure iron was studied using both conventional samples and artificial pit electrodes. Experiments were conducted in solutions of 0.01M, 0.1M and 1M NaCl at pH values of 7 and 10, and in pH 8.4 borate buffer solution containing the same levels of NaCl. The pitting potential (Epit) of pure iron is higher in buffered solutions than in non-buffered solutions of equal chloride concentration, with ΔEpit decreasing with increasing chloride concentration. Transition potential values (ET) between diffusion and activation/ohmic controlled pit growth were measured and compared with Epit results.
Local Cathodic Corrosion of n-Type InP(001) by Scratching
Authors: Seo Masahiro , Yamaya Tadafumi
Published: November 2006

The n-type InP (001) specimen highly doped with sulfur was scratched by a diamond scriber. Afterward, the scratched specimen was cathodically polarized at a constant potential, Ec, for 300 s in deaerated 0.5 M HCl in dark and sbsequently anodically polarized at a potential sweep rate of 10 mV s-1 up to - 0.1 V (SHE). The cathodic corrosion for the scratched specimen started at Ec more noble by 0.1 V than that for the as-received specimen. The cathodic corrosion proceeded preferentially on the scratched area and its vicinity during the cathodic polarization at Ec between - 0.5 V and -0.6 V (SHE). The crack lines generated by scratching were widened and deepened due to cathodic corrosion. The metallic indium deposited as a result of the cathodic corrosion was anodically dissolved during the subsequent anodic polarization.
Electrochemical Testing of Tantalum and Copper in Chemical Mechanical Polishing Slurries
Authors: Liu Zhendong , Li Hugh , Schmidt Robert , Baker Richard
Published: November 2006

Potentio-dynamic polarization, electrochemical impedance spectroscopy (EIS), and galvanic current techniques were used to study the electrochemical behaviors of copper and tantalum in chemical mechanical polishing (CMP) slurries. It was found that a chemical agent, guanidine chloride, had a significantly specific effect in etching tantalum. When tantalum was galvanically coupled to copper in a commercial CMP slurry, tantalum was preferentially corroded and copper was protected from corrosion.
Activation of Cu-Based Amorphous Alloys Ribbons for Catalytic Applications
Authors: Janik-Czachor Maria , Pisarek M. , Molnar A.
Published: November 2006

Results to develop new and effective procedures to activate Cu- Ti, Cu-Zr, and Cu-Hf amorphous alloy ribbons for catalytic applications are summarized. A wide range of activation methods has been successfully applied to transform Cu-Zr alloys into catalysts of high and stable catalytic activity and selectivity. In contrast, only specific procedures may be used to activate Cu-Ti and Cu-Hf amorphous samples. Various characterization techniques including surface enhanced Raman spectroscopy (SERS), XRD, wavelength/energy dispersive spectrometry (WDS/EDS), scanning electron microscopy (SEM), high-resolution Auger electron microanalysis (SAM), Auger electron spectroscopy (AES), porosity and surface area measurements provide data to interpret changes in structural, surface and catalytic properties.
The Effect of Tungsten Addition to the Intermediate IrO2 Layer of Mn-Mo-O/IrO2/Ti Electrodes on the Performance for Oxygen Evolution in Seawater Electrolysis
Authors: Kato Zenta , Kumagai Naokazu , Asami Katsuhiko , Hashimoto Koji
Published: November 2006

Oxygen evolution even in seawater electrolysis for hydrogen production can be done by using the electrodes consisting of the outer electrocatalytically active Mn1-xMoxO2+x layer, the intermediate iridium dioxide layer and the titanium substrate. An attempt was made to decrease the use of iridium in the intermediate layer which is necessary to avoid the growth of insulating titanium oxide on the titanium substrate during anodic deposition of the Mn1-xMoxO2+x layer and during seawater electrolysis. The addition of tungsten to the intermediate layer, the oxide of which is stable under anodic polarization in addition to high activity for oxygen evolution and very low activity for chlorine evolution in seawater electrolysis, was effective to decrease the use of iridium to 1/5.
Si-C-O Glass-like Compounds as a Negative Electrode Material for Li-Ion Battery
Authors: Konno Hidetaka , Morishita O. , Sato Shuya , Habazaki H. , Inagaki Michio
Published: November 2006

Two types of low molecular weight silicone compounds were impregnated into urethane foam pieces by sorption and cured in air. Formed block-type precursors were crushed and heat-treated at 1000-1600oC for 1 h in Ar. The Si-C-O compounds formed in a range of 1000-1300oC were glass-like by XRD and had nearly the same chemical composition, but the 1300oC product had less amounts of siloxane groups than the 1000oC product by MAS-NMR. The 1300oC product showed good cycle performance for Li+ ion insertion/extraction in 1 mol L-1 LiClO4 (EC:DEC=50:50 vol%) and no irreversible capacity except for the first cycle. The capacity was about 600 mA h g-1 at 50 mA g-1 and about 400 mA h g-1 at 200 mA g-1. In contrast, the product at lower temperature showed much higher initial capacity but it decreased steeply with number of cycles.
Binary Magnesium-Based Amorphous Alloy Precursors in the Synthesis of Methyl Isobutyl Ketone
Authors: Molnar Arpad
Published: November 2006

Results of our recent studies on the use of M-Mg(O) (M = Cu, Pd or Ni) amorphous alloy powders as catalyst precursors in the one-step conversion of acetone to methyl isobutyl ketone (MIBK) in the presence of hydrogen are summarized. Samples prepared by mechanical alloying and mechanically induced self-sustaining reaction (MSR) produce catalyst materials with varying catalytic properties. Precursor materials, in most cases, could be transformed by controlled oxidation into catalysts of enhanced activities and selectivities.
Corrosion Prevention for the Use of Renewable Energy
Authors: Hashimoto Koji
Published: November 2006

Extrapolation of primary energy consumption of the world between 1990 and 2003 will result in the complete exhaustion of oil, uranium, natural gas and coal reserves in 2030, 2038, 2040 and 2061, respectively. We are proposing global carbon dioxide recycling to use solar energy for all people in the whole world. The electricity will be generated by solar cells in the deserts and be used for production of hydrogen by seawater electrolysis at the nearby desert coasts. Hydrogen for which there is no mass transportation technology will be converted to methane at the desert coasts by the reaction with carbon dioxide recovered by energy consumers. Among systems in global carbon dioxide recycling, seawater electrolysis and methane formation have not been performed industrially. We tailored anodes for oxygen evolution without chlorine formation in seawater electrolysis, energy-saving cathodes for hydrogen production and ideal catalysts for methane formation by the reaction of carbon dioxide with hydrogen. Prevention of corrosion degradation of the key materials is the most important subject for success of the global carbon dioxide recycling.
Thermo-Chemical Expansion of SOFC Materials
Authors: Bishop Sean R. , Duncan Keith , Wachsman E. D.
Published: November 2006

The thermo-chemical expansion of Solid Oxide Fuel Cell (SOFC) component materials exposed to different partial pressures of oxygen (PO2) was studied and a model developed that fits the resulting data. Thermo-chemical expansion is made up of two parts, the expansion due to temperature and the expansion due to changes of point defect population as a function of ambient PO2 . The materials of interest in this study were 10mol% gadolinium doped ceria (GDC), undoped ceria, 8mol% yttria stabilized zirconia (YSZ), and 50vol% 8mol% yttria stabilized zirconia and 50vol% nickel (II) oxide composite (YSZ/NiO). The thermo-chemical expansion data were compared to a model that accounts for both expansion due to temperature and creation of oxygen vacancies in the lattice. The parameters of the model were determined from values in the literature. The experimental data validated the model.
Synthesis, Characterization, and Densification of Samaria Doped Ceria Ultra-Fine Powders
Authors: Esposito Vincenzo , Luong Bac , Fronzi Marco , Traversa E.
Published: November 2006

Nanometric Samaria 20% mol Doped Ceria (SDC20) powders were synthesized by a co-precipitation method. Nano-sized SDC20 powders (crystals size ~ 15 nm) were obtained by calcination at 600 {degree sign}C. The powders were formed by uniaxial pressure and then sintered. Sintering procedures were led both conventionally, at 1500 {degree sign}C for different sintering times (1, 5, 10 hours), and by fast firing process at different temperatures (1200, 1300, 1400, 1500, 1600 {degree sign}C for ~ 0.1 hour). As consequence of the thermal treatments, different resultant microstructures were observed. Electrochemical impedance spectroscopy (EIS) was used to determine total conductivity and to separate bulk and grain boundary impedance contributions. As expected, densification and electrical properties of the conventionally sintered samples showed to be mainly dependent on the average grain size. On the other hand, for the fast fired samples, lattice diffusion mechanism mainly controlled the densification, boundary arrangement and the resultant microstructures at various temperatures.
Nanostructured Materials and Mechanisms for Electrochemical Conversion and Storage
Authors: Tsagarakis Evangelos D.
Published: November 2006

With recent advances in the development of modern electronic devices, reliable energy and power sources are required to meet technological needs. Electrochemical energy conversion has certain advantages since it can cover a broad window of energy and power densities. Emphasis is given in this work to nanostructured materials that have currently attracted interest for energy storage and conversion devices. Nano-ionic bulk and interfacial aspects are taken into consideration. Moreover, modeling of electrochemical storage is utilized to translate information for the physicochemical processes and rate-determining steps involved and reveal proper choice of materials, cell design and improvement of output characteristics. Specific examples are shown for supercapacitors where experimental data are compared to simulation results. The frequency dependence of hybrid electrochemical systems is discussed and related to their transient characteristics.
Development of Higher Ionic Conductivity Ceria Electrolyte
Authors: Omar Shobit , Wachsman E. D. , Nino Juan
Published: November 2006

A co-dopant strategy was used to further investigate the doping effects on the ionic conductivity of ceria based electrolyte. Experiments were conducted using Lu3+ and Nd3+ as co-dopants, added in a proportion such that the effective dopant ionic radius matches critical dopant ionic radius for ceria electrolyte. Ionic conductivity measurements were performed on LuxNdyCe1-x-yO2-d (where x/y = 1.16) electrolytes with different total dopant concentration (x+ y) using two-point probes electrochemical impedance spectroscopy technique from 150oC to 700oC in air. In addition, to understand the effect of polarizibility alone, Lu3+ doped CeO2 was also investigated as the ionic radius of Lu3+ is approximately the same as Ce4+. LuxNdyCe1-x-yO2-d electrolytes exhibit higher ionic conductivity than LuxCe1-xO2-d, which indicates that co-doping strategy works. Around 700oC, its grain ionic conductivity surpasses that of the GdxCe1-xO2-d, which is the highest ionic conductive ceria based electrolyte.
Electrical Characterization of Semiconducting La2CuO4 for Potentiometric Gas Sensor Applications
Authors: White Briggs M. , Van Assche F. Martin , Traversa E. , Wachsman E. D.
Published: November 2006

Potentiometric sensors of the configuration La2CuO4|YSZ|Pt are sensitive to ppm-levels of NO, NO2 and CO gas while they are insensitive to %-level variations in oxygen concentration. The voltage response is determined by the Differential Electrode Equilibria. The equilibria attained at each electrode is a function of the catalytic and electrocatalytic activity as well as the often overlooked semiconductor character of the electrode. In fact, many metal oxides used as potentiometric sensor electrodes are semiconductors. The Fermi level of a semiconductor is very sensitive to gas adsorption and changes proportionally as the gas concentration does. The Fermi level can be directly related to the electrode potential. Therefore, adsorption-induced Fermi level changes make a contribution to the potentiometric response when semiconductors are used as electrode materials. We have fabricated, characterized, and compared potentiometric and conductometric sensors with La2CuO4 sensing electrodes to illustrate this effect.
Heterogeneous Catalytic Evaluation of Potentiometric La2CuO4 Sensor Electrodes
Authors: Van Assche Frederick M. , Yoo Jiho , Chatterjee Suman , Wachsman E. D.
Published: November 2006

Temperature programmed desorption (TPD) and reaction (TPR) were performed along with infrared (IR) spectrometry to determine adsorption and reaction behaviors of NOx and CO on a La2CuO4 /YSZ/Pt potentiometric sensor. TPR and TPD experiments for NO exposure on La2CuO4 revealed NO does not react to form thermodynamically favored N2, or NO2 in the presence of O2. Further, NO molecules that bond to the surface of the powder are only weakly held and desorb at low temperatures. IR analysis of the adsorption revealed extensive formation of ionic nitrate, indicating the potential voltage generated from NO exposure comes from adsorption products. NO2 TPD and TPR showed a complex desorption pattern and extensive decomposition of NO2 at high temperatures. It was concluded that the mechanism of electric potential generation from NO2 was the additive effect of several paths.
Anode-Supported Solid Oxide Fuel Cells with Thin Film Electrolyte for Operation at Reduced Temperatures
Authors: Xiao Haiming , Reitz Thomas
Published: November 2006

In order to reduce the operating temperature of solid oxide fuel cells (SOFCs), anode-supported cells incorporating thin film (~10 µm) electrolytes in conjunction with anode/electrolyte and cathode/electrolyte interlayers were studied. Anode supported button cells were prepared through a conventional approach and were analyzed via Scanning Electron Microscopy (SEM), Polarization, and Electrochemical Impedance Spectroscopy (EIS). It was found that the electro-catalytic activity and electrode/electrolyte interfacial areas were enhanced through the addition of these interlayers. This performance improvement was attributed to the introduction of a diffuse mixed conduction region associated with these interlayers. The cathode appeared to benefit disproportionately from this enhancement.
Electrical and Structural Properties of La(Fe,M)O3 (M = Mn, Ni, Cu)
Authors: Zhou Xiao-Dong , Cai Q , Yang J , Scarfino B. , James W. , Yelon W , Anderson Harlan , Shin Y. , Pederson Larry
Published: November 2006

Structural and electrical properties of doped LaFeO3 with Mn, Ni or Cu are studied by neutron diffraction, x-ray diffraction, conductivity measurements and thermoelectrical power measurements. Generation of the carriers (electron holes) in Mn and Cu doped LaFeO3 is a thermally activated process. The carrier fraction reaches a plateau determined by the dopant content. Electrical conductivity of Ni doped LaFeO3 is particularly high with a negligible activation energy, indicating Ni doped LaFeO3 is a metallic conductor, whereas conduction in Mn and Cu doped LaFeO3 is through polaron hopping.
Electrode Performance of Nanostructured La1-aSraCo1-bFebO3-x on a Ce0.8Sm0.2O2 Electrolyte Prepared by Citrate-Nitrate Auto-Combustion
Authors: Deganello Francesca S. , Esposito Vincenzo , Traversa E. , Miyayama Masaru
Published: November 2006

Nanostructured La1-aSraCo1-bFebO3-x (a=0.3-0.5; b=0-0.2) and Ce0.8Sm0.2O2 powders were successfully prepared by citrate- nitrate auto-combustion synthesis and were characterized by scanning electron microscopy and X-ray diffraction analysis. Electrochemical Impedance Spectroscopy measurements on symmetric cells were performed to evaluate the applicability of La1-aSraCo1-bFebO3-x as a cathode material for Single Chamber Solid Oxide Fuel Cells. Our results demonstrated that strontium has a positive effect while iron shows a slightly negative effect on the interfacial resistance. The effect of the electrode sintering temperature was investigated by varying the temperature from 850 {degree sign}C to 1250 {degree sign}C and the best sintering temperature was found to be 900 {degree sign}C. The best characteristics as cathode around the operating temperature of Single Chamber Fuel Cells were found for the composition with a=0.4 and the minimum iron doping; at 700{degree sign}C, an Area Specific Resistance of 0.13 ohm•cm2 was measured.
Evaluation of Time Constants Governing the Cathodic Reaction in SOFCs
Authors: Smith Jeremiah R. , Orazem Mark , Duncan Keith , Chen Aijie , Wachsman E. D.
Published: November 2006

The need for power sources has created a lot of interest in fuel cells. SOFCs with LSM and LSCF cathodes and YSZ electrolytes are materials of interest; however, the processes governing the cathodic reactions are not well understood. Impedance spectroscopy is used to evaluate the RC time constant behavior of the various electrochemical steps contributing to the cathodic reaction. This evaluation typically involves separating the various contributions using a circuit element type model. The focus of this work is to use the model parameters to determine kinetic behavior, particularly the time constants for each of the process steps contributing to the overall cathodic reaction. The determined time constants are compared for the various cathode materials tested with the goal of generating a common understanding of the kinetic behavior of the cathodic SOFC reaction.
Ag-Bi1.6Er0.4O3 as a Potential Cathode Material for IT-SOFCs
Authors: Camaratta Matthew , Wachsman E. D.
Published: November 2006

Porous composite electrodes consisting of pure silver and Er0.4Bi1.6O3 (ESB20) were synthesized and characterized using impedance spectroscopy. Pure Ag-ESB20 electrodes were optimized according to composition and long-term stability was tested. Electrode area specific resistance (ASR) was found to increase by 80% in 140h at 600åC due to migration of the silver phase. Two approaches were used to combat silver migration. First, nano-sized 8-mol% YSZ powders were added to the electrode slurries. Stability improvement was achieved at 15vol% YSZ. Second, ESB20 starting particle size was reduced using vibratory milling. This approach yielded a 25% reduction in initial ASR, a 95% reduction in ASR growth rate under no applied bias at 650åC, and a 50% reduction in ASR growth rate under a 250mV applied bias at 650åC.
Ceramic Foams for SOFC Applications.
Authors: Traversa E. , Rainer Alberto , Basoli Francesco , Licoccia Silvia
Published: November 2006

A process for the preparation of cellular solids starting form a ceramic powder and an additive-free polyurethane by means of in situ foaming and polymerization of the polymer templating matrix is presented. Ni-YSZ cermets for SOFC applications were prepared following two different processing routes. Microstructural, porosity and conductivity investigation was performed to characterize the two cermets obtained, and to evaluate the possibility of using these materials for solid oxide fuel cells application.
Synthesis and Characterization of Manganese Oxide for Redox Capacitor Prepared by Electrodeposition on Carbon Fibers
Authors: Urano Makoto , Waki Keiko
Published: November 2006

Manganese oxide (MnOx) was synthesized by electrodeposition on carbon fibers. Observation by a transmission electron microscopy (TEM) revealed that a number of MnOx nanowires with the diameter of about 7 nm were deposited onto the surface of the carbon fibers. An X-ray photoelectron spectroscopy (XPS) analysis of mean oxidization state of Mn in the deposited MnOx indicated that Mn existed as tetravalent state. The nanowired MnOx showed capacitive behavior for cyclic voltammetry (CV) measurements in a neutral aqueous electrolyte. Furthermore, the voltammograms and structural change observed by TEM suggest that dissolution and re-deposition of MnO2 occurred during CV cycling.
γ-MnO2 Synthesized from Raw Ore for Protonic Solid-Battery
Authors: Singh Kamal M. , Malankar Hemant , Acharya Smita , Bhoga Shyam
Published: November 2006

Intercalating γ-MnO2 is synthesized for protonic solid-state battery by chemical route using raw ore. Manganese sulfate obtained by leaching of raw ore precipitated as hydroxide. Later, manganese hydroxide on air-oxidation converted into manganese dioxide. The performance of the synthesized cathode material tested by fabricating protonic solid-state battery and subsequently discharged at constant load condition, indicated intercalation of protons. The intercalation process is understood in the light of structural features of γ-MnO2 and chemical bond model.
Inhibition by Polyaniline of Corrosion-Driven Coating Delamination on Carbon Steel: Aspects Regarding the Role of the Counteranion
Authors: Cook Anthony , Gabriel Andreas , Laycock Nicholas , McMurray Neil , Williams Geraint
Published: November 2006

Thin films of the polyaniline emeraldine salts of paratoluenesulphonic acid and phenylphosphonic acid have been employed to investigate the redox condition of the polymer at various regions of a coating undergoing cathodically driven delamination. Both species significantly inhibit delamination when a 0.86 mol dm-3 NaCl electrolyte contacts a penetrative coating defect. In aerated environments, three redox states of the polymer are in evidence; namely the emeraldine salt (at intact regions), the leuco base (at the delamination front) and the emeraldine base (in the delaminated region). In the absence of oxygen, the emeraldine salt is irreversibly reduced to the leuco base during delamination. These results are consistent with the notion that the emeraldine salt of polyaniline species inhibits corrosion/delamination primarily by the suppression of through-coating O2 reduction via the ennoblement of substrate potentials.
Design of Cathodic Inhibitors for AA2024-T3 Guided by Understanding Heterogeneous Cathodic Reaction Kinetics
Authors: Scully J. R. , Jakab Marta A.
Published: November 2006

The kinetics of oxygen reduction reaction (ORR) was studied on AA2024-T3 and modeled using heterogeneous reaction theory as a function of the intrinsic distribution (i.e., size and spacing) of the electrochemically active IMCs and replated copper sites. The ORR was successfully modeled by considering AA2024- T3 to behave as a regular array of Cu-rich sites in a benign Al matrix. The activation and mass transfer controlled current densities (iact and iD, respectively) associated with ORR depended on the Cu coverage. Then, the effect of environmentally friendly inhibitors (Ce3+, Co2+ and MoO42-) on the kinetics of ORR was studied on AA2024-T3 and on isolated Al-Cu-Mg as well as Al-Cu-Mn- Fe intermetallic phases. Significant reduction of both iact and iD was observed with pretreatment by all inhibitors. Models accounting for this inhibiting behavior are discussed and guidance is given on choice and testing of cathodic inhibitors.