bluuebunny/crossref_metadata_2025 huggingface dataset:
Bimetallic Ni Alloys for the Electrooxidation of Hydrazine in Alkaline Media
Authors: Martinez Ulises , Asazawa Koichiro , Halevi Barr , Olson Tim , Kiefer Boris , Datye Abhaya K. , Tanaka Hirohisa , Atanassov Plamen
Published: October 2010

Bimetallic Ni alloys and solid solutions have been synthesized using spray pyrolysis of metal nitrates. Characterization of synthesized Ni compounds was performed using XRD, SEM, TEM, and EDS, in order to confirm phase compositions. The electrochemical performance for the oxidation of hydrazine in alkaline media for four different compositions of NixZny, Ni80Zn20, Ni66Zn33, Ni50Zn50, and Ni33Zn66, and one composition of NiCo, Ni50Co50, was tested and compared to that of Ni. Highest mass activity was found in the Ni80Zn20 sample, which according to geometry matching has a Ni-Ni distance that matches the gas phase groundstate geometry of hydrazine. This finding highlights the importance of matching surface structure and molecular geometry for this and possibly other catalytic reactions.
Influence of the pH Value and the Carbonate Ion Concentration of the Electrolyte Solution on the Ethanol Oxidation at Polycrystalline Platinum
Authors: Cremers Carsten , Kintzel Birgit , Bayer Domnik , Tübke Jens
Published: October 2010

Recently, the use of alkaline anion exchange membranes has yielded some enhancement of direct ethanol fuel cells at least with respect to the achieved performances. However, so far reports have been made for cells operated with a large excess of KOH and mostly without cycling the anolyte. Under real fuel cell conditions with an anode loop, an accumulation of carbonate ions and a reduction of pH are to be expected. In order to evaluate the effect of these changes on the ethanol oxidation reaction, the ethanol oxidation was studied at polycrystalline platinum thin film electrodes in electrolyte solutions with different pH values and varying carbonate ion concentrations. No severe detrimental effects of high carbonate ion concentration were found. The pH of the electrolyte has an effect depending on the concentration of ethanol. At high ethanol concentrations relevant for fuel cells an optimum value would be around pH 12.
Borohydride Oxidation on Pt-Based Electrodes: Evidence of Residence Time Effect on the Reaction Onset and Faradaic Efficiency
Authors: Freitas KÊnia S. , Concha Belén Molina , Ticianelli Edson A. , Chatenet Marian
Published: October 2010

The borohydride oxidation reaction (BOR) was studied on Vulcan XC72-supported Pt active layers by cyclic voltammetry in 0.1 M NaOH / 10−3 mol L-1 NaBH4. The BOR onset potential and the number of electrons (ne-) exchanged per BH4- anion (faradaic efficiency) were investigated for active layers of different thickness and/or compositions, to determine whether the residence time of reaction intermediates does influence the reaction. The results indicate that the ne- value exchanged in the BOR strongly depends on the thickness of the active layer. While thin (ca. 0.5 µm-thick) Pt/C active layers yield ne- < 4, thick layers (approximately 3 µm) yield ne- ≈ 8, which can be ascribed to the sufficient residence time of the molecules formed within the active layer (H2 by heterogeneous hydrolysis or BOR intermediates). This puts into evidence that not only the nature of the electrocatalyst is important to reach high BOR efficiency, but also the structure/thickness of the active layer.
Role of Graphene as a Catalyst Support in SOM Oxidation
Authors: Uhm Sunghyun , Joo Jiyong , Bong Sungyool , Kim Hasuck , Lee Jaeyoung
Published: October 2010

Highly dispersed and stable Pt and Pd on graphene nanasheets (GNS) catalysts were synthesized via a colloidal method using graphene oxide formed by chemical exfoliation. GNS can provide an efficient 2-D planar structure where metal nanoparticles may be able to deposit with maximum utilization so that particle size control and its distribution on GNS are more favorable compared to commercially available carbon black, especially Vulcan-XC. Even in case of more than 60% Pd, homogenous deposition is readily achievable in conjunction with smaller particle size. However, due to the morphological characteristics of graphene oxide or the formation of larger catalysts aggregate, superior electrocatalytic activity cannot be obtained. An important advantage of this catalyst support is to provide strong metal-support interaction, thereby increasing catalyst stability of Pd catalyst for formic acid oxidation.
Effect of Carbonate on Oxygen Reduction, Hydrogen Oxidation and Anion Exchange Membrane Chemical Stability
Authors: Vega Jose A. , Chartier Casey , Smith Shawna , Mustain William E.
Published: October 2010

The tolerance of anion exchange membrane fuel cell components to CO2 and carbonate was investigated. Addition of CO2 to the cathode stream of an anion exchange membrane fuel cell caused an improvement in the performance, suggesting partial operation under the carbonate cycle. Exposure of anion exchange membranes to concentrated hydroxide environments caused a decrease in the ionic conductivity attributed to membrane chemical degradation. Exposure of the membranes to concentrated carbonate environments had no measurable effect on the ionic conductivity over a 30 day period. Addition of carbonate/bicarbonate had a small effect on the oxygen reduction reaction. An increase in the anion concentration caused a positive shift in the Tafel slope and a decrease in oxygen saturation concentration and diffusion coefficient. Hydrogen oxidation follows a 2-electron pathway in the presence of hydroxide or carbonate, and a small effect is observed for the exchange current comparing OH- to CO32-.
Open Frame Structures for Nonplatinum Catalysts: Colloidal Approach to Transition Metal/Nitrogen-Containing Carbon-Supported Electrocatalysts
Authors: Robson Michael , Patterson Wendy , Petsev Dimiter , Atanassov Plamen
Published: October 2010

Carbon supported non-platinum catalysts that facilitate the oxygen reduction reaction can be templated onto a mesoporous silica substrate to provide a great deal of control over the porosity of the catalytic material after the silica has been etched. This colloidal approach, in conjunction with dry impregnation of catalyst precursors, provides an avenue to engineer the surface morphology of the catalyst whereby optimal performance can be achieved.
Effect of Reduction Temperature of Fe-Co-Ni/C Catalyst on the Solid Alkaline Fuel Cell Performance
Authors: Nakamura Ayaka , Takahashi Hiroki , Takeguchi Tatsuya , Yamanaka Toshiro , Wang Qi , Uchimoto Yoshiharu , Ueda Wataru
Published: October 2010

In this present work, the effect of reduction temperature of Fe-Co-Ni/C anode catalyst on the solid alkaline fuel cell performance was investigated. Fe-Co-Ni/C anode catalysts were prepared by the impregnation method, and reduced at 360°C, 500°C, and 900°C in hydrogen flow for 2 h. The order of the maximum power density was as follows: Fe-Co-Ni/C with reduction at 360°C > reduction at 500°C > reduction at 900°C. The maximum power density of 17 mW cm-2 was obtained for the cell with Fe-Co-Ni/C anode reduced at 360°C. The order of the particle size was as follows: Fe-Co-Ni/C with reduction at 360°C < reduction at 500°C < reduction at 900°C. Fe-Co-Ni/C reduced at 360°C with the smallest particle size showed the highest activity for hydrogen oxidation reaction.
Performance of Solid Alkaline Fuel Cells Employing Layered Perovskite-Type Oxides as Electrolyte
Authors: Watanabe Hiroshi , Takahashi Hiroki , Takeguchi Tatsuya , Yamanaka Toshiro , Ueda Wataru
Published: October 2010

Layered perovskite-type oxides were characterized by electrochemical measurement. Five kinds of perovskite oxides (LaSr3Fe3O10, NaLaTiO4, Sr4Co1.6Ti1.4O8(OH)2⋅xH2O, RbLaNb2O7 and LaFeO3) were used as electrolyte of fuel cells. Every perovskite oxide could generate current and high open circuit voltage (>0.8 V). The results were attributed to hydroxide ion (OH-) conduction resulting from reduction and H2O treatments. This hypothesis suggests that the possibility of a new alkaline fuel cell by using layered perovskite as electrolyte.
Development of Novel NaCo2O4 Film Electrolyte for Alkaline Fuel Cells
Authors: Matsuda Motofumi , Murota Tadatoshi , Takahashi Hiroki , Takeguchi Tatsuya , Ueda Wataru
Published: October 2010

In this work, we developed thin-film anion-conducting NaCo2O4 electrolyte for solid alkaline fuel cell composed. The NaCo2O4 powder was slurried with poly vinylidene difluoride (PVDF) and N-methyl pyrrolidone (NMP). The slurry was once or twice painted on the punched metal base by the doctor blade method, followed by calcination at 600{degree sign}C for 5 h. In addition, wet powder spraying method was applied. In preparing NaCo2O4 film, the density of the NaCo2O4 greatly affected the cell performance. The cell made by twice-casting doctor blade method showed higher performance than other method since its density of NaCo2O4 increased.
Determination of Carbonate Ion in MEA during the Alkaline Membrane Fuel Cell (AMFC) Operation
Authors: Watanabe Shin , Fukuta Kenji , Yanagi Hiroyuki
Published: October 2010

Measurements of the ion ratio (OH-, CO32- and HCO3-) in MEA during the operation was reported. The ratio of ions in MEA depended on the current density. The amount of CO32- in MEA could be reduced in the case of using clean air for the oxidant. On the other hand, the CO32- ratio in MEA did not change during the long time operation in the case of using ambient air for the oxidant. There is a possibility to enhance the cell performance with ambient air oxidant by boosting the release of CO2 from anode.
The Use of Statistical Mechanics for Hydroxyl Ion Transport in an Alkaline Anion-Exchange Membrane
Authors: Cassenti Brice N. , Grew Kyle , Chiu Wilson
Published: October 2010

A statistical mechanics model based on the time-dependent Liouville equation is applied to the diffusion of hydroxyl ions in an alkaline anion exchange membrane. The original model developed for Nafion was modified to facilitate an effective numerical implementation. The model results showed a significant dependence of the diffusion on the ion size (i.e., the outer electron distribution), but for likely ion sizes the diffusion coefficient was found not to be significantly different from the nominal value in water. The specific numerical implementation was computationally competitive with molecular dynamics implementations, but presents considerable mathematical difficulties requiring approximations to obtain solutions.
High Molecular Weight Copolymer Alkaline Fuel Cell Membrane via Miniemulsion Polymerization
Authors: Luo Yanting , Guo Juchen , Wang C. , Choi Kyu Yong , Chu D.
Published: October 2010

A novel copolymer, named QPMBV (quaternized poly (methyl methacrylate-co-butyl acrylate-co-vinyl benzylchloride), PMBV) has been synthesized as the solid alkaline electrolyte in AFC. Miniemulsion polymerization has been used to achieve high molecular weight to enhance mechanical property. GPC (Gel permeation chromatography), H1-NMR (Proton nuclear magnetic resonance), and DSC (Differential scanning calorimetry) techniques were employed to characterize the copolymer. Performance tests were carried out to show the potential of this AEM, as the peak power can reach 25mW/cm2 at the current of 40mA/cm2 in the relative humidity of 80% at 60°.
Quarternary Ammonium and Phosphonium Based Anion Exchange Membranes for Alkaline Fuel Cells
Authors: Arges Christopher G. , Kulkarni Sunil , Baranek Austin , Pan Ke-Ji , Jung Min-Suk , Patton Derek , Mauritz Kenneth A. , Ramani V.
Published: October 2010

In this work, Udel® polysulfone was functionalized with quaternary ammonium and phosphonium based cations for thin-film anion exchange membranes (AEMs). At this time, discussion is limited to the chemical, mechanical, and thermal attributes of quaternary ammonium polysulfone (QAPSF). Key results indicate that the thermal properties of QAPSF are well suited for low temperature fuel cells, but improvement to QAPSF conductivity and mechanical properties is needed for durable and high performing alkaline fuel cells. It was observed that water uptake of nearly 15% of the normalized membrane weight is needed to facilitate ion conductivity in the QAPSF membrane. Finally, fuel cell performance is demonstrated with a QAPSF membrane electrode assembly.
Recent Advances in TOYOTA FCHV-adv Fuel Cell System
Authors: Sekizawa Koshi , Kitamura Nobuyuki , Manabe Kota , Nonobe Yasuhiro , Kizaki Mikio , Kojima Koichi
Published: October 2010

Toward the mass introduction start in 2015, Toyota continues efforts to overcome the remaining technical challenges for the commercialization of the TOYOTA FCHV. The cold start capability is one of the main issues among such challenges. An excess amount of water in fuel cells hinders the cold start, because the water turns into ice. On the other hand, when there is a lack of water in fuel cells, the initial FC output decreases. To resolve the issue of the cold start capability, the AC impedance measurement was employed for estimating the water content in the FC stack. Based on this, the water management system was developed, and it became possible to start up the FCHV at temperatures down to -30{degree sign}C.
Development of Supported Bifunctional Oxygen Electrocatalysts with High Performance for Unitized Regenerative Fuel Cell Applications
Authors: Huang Sheng-Yang , Ganesan Prabhu , Jung Won Suk , Cadirov Nicholas , Popov Branko N.
Published: October 2010

Titania supported platinum and iridium electrocatalysts (Pt/TiO2 and Ir/TiO2) were synthesized and investigated as bifunctional oxygen electrode (BOE) catalysts for unitized regenerative fuel cells (URFCs). TEM images revealed uniform distribution of Pt and Ir nanoparticles on the TiO2 support. Histogram analysis showed particle sizes of Pt and Ir to be 4.5 and 2.0 nm, respectively, which was also confirmed by the XRD characterization. Among the various Pt-Ir compositions prepared, Pt85Ir15 (with a Pt/Ir weight ratio of 85/15) showed the highest catalyst efficiency towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The URFC testing results showed that the round-trip energy conversion efficiency (εRT) of supported Pt-Ir/TiO2 (42%) was significantly higher than that of unsupported PtIr black (30%). The TiO2 support provided high surface area for uniform dispersion of the catalyst particles. The URFC performance increase was ascribed to the uniform dispersion and better utilization of noble metal catalysts.
New Ionic Liquids Containing Fluorosulfonyl(trifluoromethylsulfonyl)amide and 5-Phosphoniaspiro[4.4]nonan
Authors: Matsumoto Hajime , Umecky Tatsuya , Tsuzuki Seiji
Published: October 2010

ew room temperature ionic liquids (RTILs) containing phosphoniaspiro[4.4]nonan (PS4,4+) could be obtained by selecting an amide anion with structural asymmetry such as fluorosulfonyl (trifluoromethylsulfonyl) amide (FTA-). PS44+ could not form RTILs with another amide anion such as FSA- ([(FSO2)2N]-, and TFSA- ([(CF3SO2)2N]-), which indicated that the structural asymmetry in an anion effectively decreasing the melting point of symmetric phosphonium such as PS4,4+.
Highly Efficient Extraction of Phenols from Aqueous Solution Using Magnetic Room Temperature Ionic Liquids
Authors: Deng Ning , Li Min , De Rooy Sergio L. , El-Zahab Bilal , Warner Isiah
Published: October 2010

Water-insoluble magnetic room temperature ionic liquid (MRTIL), [3C6PC14][FeCl4], was synthesized from trihexyltetradecylphosphonium chloride and FeCl3.6H2O. The MRTIL was used for solvent extraction of phenols from aqueous solution. Due to its strong paramagneticity, [3C6PC14][FeCl4] can respond to an external magnetic field, which was employed to design a novel magnetic extraction technique. Extraction conditions such as extraction time, volume ratio between MRTIL and aqueous phase, and pH were optimized. Phenols with multiple chlorine substituents exhibited higher distribution ratios. Compared with four traditional non-magnetic ionic liquids, the MRTIL exhibited significantly higher extraction efficiency.
Grass to Gas: Ionic Liquid Based Conversion of Biomass to Fuels
Authors: McIlvaine William B. , Foley Matthew P. , Reichert William M. , Mandia Jeremy J. , Haverhals Luke M. , O'Sullivan Daniel W. , De Long H. C. , Trulove P. C.
Published: October 2010

Fossil fuels are being rapidly depleted and a novel and renewable source of hydrocarbons needs to be found. One source of untapped energy is cellulose. Work has shown that ionic liquids can dissolve and enable the facile processing of cellulose. This research shows that 1-methylimidazolum-3-ethylsulfonic acid triflate, an ionic liquid catalyst, can be used as a catalyst for the depolymerization of cellulose in an ionic liquid at greater than 50% conversion to reducing sugars. It also shows the main product of the reaction is glucose which is further dehydrated into 5-(Hydroxy-methyl) furfural. This investigation evaluated the effects of time, temperature, and co-catalyst on the reaction products and rate of the reaction.
Selective Gas Absorption by Ionic Liquids
Authors: Shunmugavel Saravanamurugan , Kegnæs So̸ren , Due-Hansen Johannes , Gretasdottir Thorey , Riisager Anders , Fehrmann Rasmus
Published: October 2010

Reversible absorption performance for the flue gas components CO2, NO and SO2 has been tested for several different ionic liquids (ILs) at different temperatures and flue gas compositions. Furthermore, different porous, high surface area carriers have been applied as supports for the ionic liquids to obtain Supported Ionic Liquid-Phase (SILP) absorber materials. The use of solid SILP absorbers with selected ILs were found to significantly improve the absorption capacity and sorption dynamics at low flue gas concentration, thus making the applicability of ILs viable in technical, continuous flow processes for flue gas cleaning. The results show that CO2, NO and SO2 can be reversible and selective absorbed using different ILs and that Supported Ionic Liquid-Phase (SILP) absorbers are promising materials for industrial flue gas cleaning. Absorption/desorption dynamics can be tuned by temperatures, pressures and gas concentrations.
Carbon Composite with Pt Nanoparticles Prepared by Room-Temperature Ionic Liquid-Sputtering Method
Authors: Yoshii Kazuki , Tsuda Tetsuya , Torimoto Tsukasa , Kuwabata Susumu
Published: October 2010

The Pt nanoparticles were prepared by direct Pt sputtering onto trimethyl-n-propylammonium bis((trifluoromethyl)sulfonyl)amide (Me3PrNTf2N) room-temperature ionic liquid (RTIL) without a stabilizing agent. The mean particle size (2.3 {plus minus} 0.1 nm) was maintained substantially constant independently of the sputtering time if the sputtering time was less than 1800 sec. The obtained Pt nanoparticles were well-dispersed in the RTIL and could be immobilized on single-walled carbon nanotube (SWCNT) by a simple process that was established in this research. The Pt-SWCNT composite material showed a remarkable catalytic activity to electrochemical oxygen reduction reaction more than a commercially available Pt nanoparticle-carbon composite catalyst. It suggests that the Pt-SWCNT composite material is one of the promising electrode catalysts for a PEM fuel cell system.
Fluorescence Activity of Green Fluorescent Protein in Ionic Liquids
Authors: Haverhals Luke M. , DaBronzo Courtney L. , Schlessman Jamie L. , Reichert William M. , De Long H. C. , Trulove P. C.
Published: October 2010

In this study the fluorescence activity of a mutant form of Green Fluorescent Protein (GFP), GFPuv, was explored in ionic liquid solvents. Purified GFPuv was obtained and experiments probing the fluorescence spectral properties of GFPuv in a series of solvents were undertaken. Data show that GFPuv is fluorescent in several ionic liquid solvents when sufficient water is also present, and the amount of water (in the solvent system) is critical in determining the fluorescent activity. Results are interpreted with regards to previous Hofmeister series correlations in attempt to rationalize solvating and stabilizing properties of the solvent systems investigated.
(Invited) Physical Properties of High Temperature Molten Salts
Authors: Sato Yuzuru
Published: October 2010

High temperature molten salts are very important in the industrial field such as active metal production. In any cases including the use as the electrolyte, the physical properties, for example, density, electrical conductivity, viscosity are essentially important. On the other hand, molten salts consist of ions and are agglutinated by the coulombic interaction. The ionicity of the molten salts is affected by the strength of coulombic force of the constituent ionic species. Too strong coulombic force makes the salts non ionic, for example, SiCl4, and prevents the formation of stable ionic molten salts. Therefore, the phenomena of complex formation are important to consider the properties of molten salts. The author studied various physical properties of many molten salts. In this paper, the physical properties are described related to the ionic constitution including complex formation in the molten salts.
Electrochemical Behavior of Dissolved Titanium Species in Molten Salts
Authors: Haarberg Geir Martin , Kjos Ole S. , Martinez Ana Maria , Osen Karen S. , Skybakmoen Egil , Dring Kevin
Published: October 2010

The electrochemical behaviour of dissolved titanium species was studied in different molten salt electrolytes. In molten chloride electrolytes the presence of Ti (III) and the tendency for disproportionation of Ti (II) into TI (III) and Ti (0) cause poor current efficiencies. In molten fluoride containing electrolytes the deposition of titanium occurs from Ti (III) since Ti (II) species are unstable. The use of an anode consisting of titanium oxycarbide combined with a liquid cathode is a promising approach to produce pure titanium.
Current Efficiency for Aluminum Electrowinning from Cryolite-Alumina Melts in a Laboratory Cell
Authors: Haarberg Geir Martin , Armoo Joseph P. , Gudbrandsen Henrik , Skybakmoen Egil , Solheim Asbjo̸rn , Jentoftsen Trond Eirik
Published: October 2010

The current efficiency with respect to aluminium was determined in controlled laboratory experiments based on the amount of aluminium deposited during galvanostatic electrolysis. Values ranging from 93 - 96 % were obtained by varying the cathodic current density and the AlF3 content.
Electrochemical Corrosion Behavior of Refractory Metals in LiCl-Li2O Molten Salt
Authors: Misra Mano , Raja Krishnan S. , Ruppert Jesse
Published: October 2010

In a typical electrochemical cell, platinum wire is used as an anode for electrolytic reduction of UO2 spent LWR fuel in a molten salt system consisting of LiCl + 2-8 wt% Li2O. During the electrolysis, the metallic lithium migrates to the anode and attacks the platinum wire. Stability of the anode material is critical for sustained operation of the electrolytic UO2 reduction cell for reprocessing spent nuclear oxide fuels. This investigation aims at developing dimensionally stable anode materials for sustained operation under aggressive conditions. The investigated materials are: tungsten, molybdenum, hafnium, and tantalum, and stainless steels type 304 and 316. Corrosion properties of the candidate materials are compared with that of platinum using electrochemical polarization and impedance spectroscopy results. In order to simulate the lithium attack on the anode material, lithium was cathodically deposited and equilibrated for about one hour before starting the anodic polarization test in LiCl + 2 wt% Li2O molten salt at 650°C. Platinum samples showed an extensive surface cracking due to penetration of lithium. Type 316 stainless steel samples showed higher impedance and smaller passive current density than that of platinum at lower anodic potentials. Tungsten samples showed higher electrochemical impedance modulus and better passivity than any other materials tested in this study.
Microstructures of Electro-Carburized Mild Steels
Authors: Siambun Nancy J. , Zheng Chen George , Hu Di
Published: October 2010

The molten carbonate salts based electro-carburisation process, as reported here, is non-toxic, environment friendly, cheaper than the cyanide based techniques and highly effective in turning mild steels into a more valuable metal. The effectiveness of the electro-carburisation process was investigated by microstructure analysis. The sample was ground, polished and then etched in a 2 % nital solution. Examinations of the microstructural changes in the etched samples by SEM-BSE and microscope (500X magnification) revealed the distribution of carbon throughout the electro-carburised mild steel. The changes were typically represented by two phases, namely, the brighter areas resulting from the ferrite phase (iron rich), and the darker areas indicating the presence of carbon in the pearlite phase which were consisted of alternate stripes of ferrite and cementite (carbon rich). These microstructural features, particularly the ferrite and pearlite regions, were found to be affected by the cell voltages applied during electro-carburisation and the type of molten salts.
Electrochemical Formation of Nd-Ni Alloys in Molten LiF-CaF2-NdF3
Authors: Nohira Toshiyuki , Kobayashi Seitaro , Kobayashi Katsutoshi , Hagiwara Rika , Oishi Tetsuo , Konishi Hirokazu
Published: October 2010

The electrochemical formation of Nd-Ni alloys was investigated in a molten LiF-CaF2-NdF3 (0.30 mol%) system at 1123 K. Cyclic voltammetry and open-circuit potentiometry indicated the formation of several phases of Nd-Ni alloys. The whole electrode became almost NdNi2 phase by potentiostatic electrolysis of a 0.2 mm-thick Ni plate at 0.15 V vs. Li+/Li for 75 minutes. The formed NdNi2 electrodes were transformed to other phases such as NdNi3 and NdNi5. The existences of NdNi2, NdNi3 and NdNi5 were confirmed by powder XRD analysis. By summarizing the results, the formation potential for each alloy phase has been determined.
Electrical Conductivity of Molten Fluoride-Chloride Electrolytes
Authors: Dedyukhin Alexander , Redkin Alexander , Apisarov Alexey , Zaikov Yurii
Published: October 2010

Electrical conductivity of fluoride-chloride melts is discussed. The available experimental data for binary and ternary systems are analyzed and presented as a molar volume function.
Electrochemical Behavior of Titanium, Silicon and Boron Oxides in Cryolite-Alumina Melts
Authors: Devyatkin Sergei V. , Pisanenko Alexander , Sarychev A.Yu.
Published: October 2010

The possibility of electrochemical synthesis of refractory compounds in the system Ti-Si-B from cryolite-alumina melts containing titanium, silicon and boron oxides has been examined using cyclic voltammetry. The electrochemical synthesis processes have been shown to be one-step, which makes it possible to obtain by electrolysis both powders and coatings on current-conducting substrates.
Spectroelectrochemical Study of Stainless Steel Corrosion in NaCl-KCl Melt
Authors: Abramov Alexander V. , Polovov Ilya B. , Volkovich Vladimir A. , Rebrin Oleg I. , Griffiths Trevor R. , May Iain , Kinoshita Hajime
Published: October 2010

High-temperature spectroelectrochemestry was applied to study corrosion of various types of stainless steel in molten salts. The electronic absorption spectra of products of anodic dissolution of stainless steel major components (iron, chromium, nickel, molybdenum, manganese, titanium) were measured in NaCl-KCl melt at 750 °C. The effectiveness and limitations of applying spectroscopic method for studying alloys corrosion was demonstrated on example of anodic dissolution of AISI 316L, 316Ti and 321 austenitic steels. The major corrosion products of steels are iron, manganese and chromium species. Prolongation of anodic dissolution leads to increasing chromium-to-iron ratio in the melt. Titanium in steels forms very stable carbonitride species that aren't dissolved during anodic oxidation.
(Invited) Notes on the Application of the Kornyshev Model for Capacitance in Ionic Liquids
Authors: Kobrak Mark
Published: October 2010

Kornyshev[J. Phys. Chem. B, 111 5545 (2007)] recently published a model of capacitance in molten salts. We apply the model to the description of an experimental capacitance curve, and discuss its interpretation.
Electrochemical Capacitors Using Fluorohydrogenate Ionic Liquid Electrolytes
Authors: Matsumoto Kazuhiko , Takahashi Kenji , Senda Atsushi , Nohira Toshiyuki , Hagiwara Rika
Published: October 2010

Electrochemical capacitors using fluorohydrogenate ionic liquids show a large voltage dependence of capacitance with a maximum at a charging voltage around 2.5 V, resulting in a larger capacitance than those using other typical ionic liquid electrolytes. The voltage dependence becomes less remarkable with decrease in the HF composition n in EMIm(FH)nF (EMIm: 1-ethyl-3-methylimidazolium). Cyclic voltammetry using an activated carbon working electrode revealed that two redox reactions occur at the higher and lower potentials against the rest potential in EMIm(FH)2.3F. These Faradaic processes contribute to the voltage dependence of capacitance.
Synthesis of New Protic Ionic Liquids for Fuel Cells on the Basis of In Situ FT-IR Measurements
Authors: Munakata Hirokazu , Tashita Takamitsu , Haibara Masaki , Kanamura Kiyoshi
Published: October 2010

A series of protic ionic liquids (ILs) were synthesized from N,N-diethylmethylamine (dema) and three kinds of imides having different fluoroalkyl chain lengths (H-N(SO2(CF2)nF)2, n = 0~2) as electrolytes for fuel cells. The effect of anion structure on the oxygen reduction reaction (ORR) activity of Pt electrode was investigated in detail using the prepared ILs. As increasing n of imide-anion, the ORR current was increased. The onset potential for ORR was also shifted towards the positive side as extending the fluoroalkyl chain of imide-anion. This potential shift was clearly revealed by in-situ FT-IR measurement to relate the anion adsorbability on the Pt electrode, depending on the fluoroalkyl chain length of imide structure.
Voltammetric Investigations of Ketone Complexation by Lewis Acids in Ionic Liquids
Authors: Cheek Graham T.
Published: October 2010

The interaction of fluorenone with scandium(III) trifluoromethanesulfonate (Sc(TfO)3) has been investigated in the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoro-methanesulfonate (BMPY TfO). The formation of two Sc3+ : fluorenone complexes is suggested by the appearance of two reduction processes, shifted positive from the original fluorenone reduction process, upon addition of Sc(TfO)3. A weak interaction of Sc(TfO)3 with fluorenone radical anion is also observed. An interesting contrast with the behavior of Hf(TfO)4 toward fluorenone is noted, the Hf(TfO)4 : fluorenone interaction being generally stronger than that of Sc(TfO)3.
Electrochemical Preparation of Nickel and Iron Nanoparticles in a Hydrophobic Ionic Liquid
Authors: Zhu Yanli , Katayama Yasushi , Miura Takashi
Published: October 2010

The preparation of nickel and iron nanoparticles was attempted in a hydrophobic room-temperature ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifloromethylsulfonyl)amide (BMPTFSA) containing Ni(TFSA)2 or Fe(TFSA)2. A potentiostatic cathodic reduction of Ni(II) in Ni(TFSA)2/BMPTFSA at - 2.6 V made the color of the electrolyte change from yellow to black and resulted in formation of Ni nanoparticles, which were confirmed by transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDX). Addition of acetonitrile (ACN) into Ni(TFSA)2/BMPTFSA resulted in a reduction of the mean diameter of Ni nanoparticles from about 3 nm to 1 nm. This may be due to the changes in the coordination environment of the Ni(II) species in the ionic liquid, from [Ni(TFSA)3]- to [Ni(ACN)6]2+. The mean diameter of Fe nanoparticles, which were prepared from Fe(TFSA)2/BMPTFSA, was close to that of Ni nanoparticles.
Irradiation-Induced Metal Nanoparticles in Room-Temperature Ionic Liquid
Authors: Tsuda Tetsuya , Sakamoto Taiki , Nose Takayuki , Seino Satoshi , Imanishi Akihito , Uematsu Taro , Kuwabata Susumu
Published: October 2010

Metal nanoparticles were prepared with γ-ray and accelerator electron beam irradiation in the 1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide (BuMeIm+Tf2N-) room-temperature ionic liquids. As for Au nanoparticles yielded in this investigation, the γ-ray irradiation made the particle size smaller compared to that by the accelerator electron beam irradiation. It is interesting to note that the nanoparticles prepared in this article were very stable although the surface was not covered with a stabilizing agent, which is usually employed so as to prevent aggregation. Similarly, other metal nanoparticle productions such as Ag, Cu, Mg, Al, Zn, and Fe were also investigated by means of the accelerator electron beam irradiation. In addition, some RTILs with Au nanoparticles yielded by the irradiation experiment showed fluorescent behavior under ultraviolet irradiation of 365 nm. It implies that the RTILs contain Au nanoparticles as well as Au clusters that cannot be observed by a common TEM system. In this study, we also found that the Si wafer, on which NaAuCl4⋅2H2O-added RTIL was spread, has distinctive two-dimensional Au microstructure crystals on the surface after the accelerator electron beam irradiation.
The Influence of Potential Under Diffusion-Controlled Region on Electrodeposition of Silver in an Amide-Type Ionic Liquid
Authors: Fukui Ryuta , Katayama Yasushi , Miura Takashi
Published: October 2010

The electrodeposition of Ag was studied in several ionic liquids. When the potential applied more negative than −0.25 V vs Ag/Ag(I), current density reached the diffusion-controlled region. The surface morphology of electrodeposited Ag changed depending on the applied potential. This result indicates that the applied potential affects the processes of Ag electrodeposition under diffusion-controlled region. Surface morphology was considered related closely to the crystal growth process. Since the electrode reaction rate is controlled by diffusion, the change of the surface morphology may be caused by the change of the double layer structure, which is expected to depend on the applied potential.
Surface Finishing of Mg Alloys by Al Electroplating in AlCl3-EMIC Ionic Liquid
Authors: Ueda Mikito , Tabei Yasushi , Ohtsuka Toshiaki
Published: October 2010

In order to improve the corrosion resistance of Mg and its alloys, Al layer was electrodeposited on their surface from aluminum chloride-1-ethyl-3-methylimidazolium chloride ionic liquid (AlCl3-EMIC). Mirror-like Al surface can be electroplated in AlCl3-EMIC ionic liquid by pulse electrolysis at 323 K, though Al layer was not dense and homogeneous. A dense and flat Al layer was successfully electroplated on Mg alloys in the AlCl3-EMIC ionic liquid at lower temperature of 283 K.
Electrodeposition of Selenium from the 1-Ethyl-3-Methylimidazolium Chloride-Tetrafluoroborate Room-Temperature Ionic Liquid
Authors: Chou Li-Hsien , Sun I-Wen , Hussey Charles L.
Published: October 2010

Electrodeposition of the selenium film in 1-ethyl-3-methylimidazolium chloride-tetrafluoroborate ionic liquid containing excess chloride ions on indium tin oxide (ITO) coated glass electrodes was studied at 30oC. Cyclic voltammogrammetric results indicate that the reduction reaction of Se(IV) is a complicated behavior and the Se film is not easy to be stripping. Scanning electron microscopy reveals that the morphology of the selenium deposits is affected by the applied deposition potential and X-ray powder diffraction data indicates the Se deposits is the crystalline of t-Se phase.
Analysis of Cationic Structure in Some Room Temperature Molten Fluorides and Dependence of Their Ionic Conductivity and Viscosity on HF-Concentration
Authors: Tasaka Akimasa , Nakai Takaaki , Inoue Hidemi , Nakanishi Kenta , Isogai Tomohiro , Kohara Shinji , Saito Morihiro , Inaba Minoru
Published: October 2010

To understand the ionic and non-ionic species in (CH3)4NF⋅mHF, (CH3)3N⋅mHF, (C2H5)4NF⋅mHF, and (C2H5)3N⋅mHF melts, the structures of these melts were investigated by infrared spectroscopy, NMR and high-energy X-ray diffraction. IR spectra revealed that the complex fluoride anions such as (HF)nF- (n = 1, 2, 3) and molecular HF are present in all melts. Ionic conductivity and viscosity of these melts were measured and correlated with their cationic structure. The ionic conductivity of the R4N+-systems was higher than those of corresponding R3NH+-systems. (CH3)4N+ and (CH3)3NH+ cation gave higher ionic conductivity than (C2H5)4N+ and (C2H5)3NH+ cation, respectively. It was concluded that these effects on ionic conductivity can be explained by the cationic structure and the concentration of molecular HF in the melts.
Interactions of Perfluoroalkyltrifluoroborate Anions with Cations: Effects of Perfluoroalkyl Chain Length on Motion of Ions in Ionic Liquids
Authors: Tsuzuki Seiji , Umecky Tatsuya , Matsumoto Hajime
Published: October 2010

The stabilization energies (Eform) for the formation of the perfluoroalkyltrifluoroborate complexes with Li+ and 1-ethyl-3- methylimidazolium cation (emim+) were calculated at the MP2/6- 311G** level. The order of the Eform calculated for the Li+ complexes is Li[BF4] >> Li[BF3CF3] > Li[BF3C2F5] ~ Li[BF3C3F7] ~ Li[BF3C4F9]. The Eform calculated for the emim+ complexes have the same order, while they are substantially smaller than those for the Li+ complexes. The calculations suggest that the weaker interactions of the BF3CF3- with emim+ compared with the BF4- are the cause of the lower viscosity of the [emim][BF3CF3] ionic liquid compared with the [emim][BF4] ionic liquid. The trend of the experimentally observed perfluoroalkyl chain length dependence of the self-diffusion coefficients of ions is well reproduced by molecular dynamics simulations. The correlation of the rotational relaxation of the emim+ and the self-diffusion coefficients of the cation and anion suggests that the translational motion of ions in the ionic liquids is associated with the rotational motion of the emim+.
Thermally Stable Nanoporous Gold-Alumina Core-Shell with Tunable Optical Transmission
Authors: Qian Lihua , Das Biswajit
Published: October 2010

Tuning localized surface plasmon resonance (LSPR) of nanoporous metals is crucial to manipulate light within tiny volumes for the implementation of optical devices at the nanoscale. Herein, nanoporous gold-alumina core-shell films with constant gold skeleton and variable alumina sheaths are fabricated by means of chemical corrosion and subsequent atomic layer deposition. Optical transmission properties of these composite films can be tailored due to LSPR excitations of the three-dimensional gold skeleton and alterable alumina shells as the surrounded dielectrics. The widely tunable light transmission and significantly improved stability are thus suggested to incorporate nanoporous gold-alumina core-shells into promising nano-devices with reliable performance.
Electrophoretic Light Scattering for Surface Zeta Potential Measurement of ALD Metal Oxide Films
Authors: Gu Diefeng , Yalcin Sinan , Baumgart Helmut , Qian Shizhi , Baysal Oktay , Beskok Ali
Published: October 2010

The zeta potential and the isoelectrical points of ALD grown Al2O3, TiO2, and ZrO2 thin metal oxide films were measured by electrophoretic light scattering technique over a wide range of pH values. The magnitude of the zeta potential of the three ALD films decreases as the concentration of the KCl electrolyte increases, while the ZPC is almost the same for various electrolyte concentrations. The ALD Al2O3 film surface was found to have the highest magnitude in zeta potential in the important pH value range of 5.5 to 7. The zero point charge of alumina (Al2O3) has been measured to occur at pH values exceeding 8. In contrast, the zero point charge of titania (TiO2) occurred at a pH value of about 6.
The Influence of Ions and Photons during Plasma-Assisted ALD of Metal Oxides
Authors: Profijt Harald B. , Kudlacek Pavel , Van de Sanden M. C. M. , Kessels W. M. M.
Published: October 2010

The influence of oxygen ions and photons during remote plasma atomic layer deposition (ALD) of metal oxide thin films was investigated for pressures of 0.5-3 Pa and plasma powers of 100-500 W. Ions have kinetic energies of ~15-35 eV and fluxes of ~10^13-10^14 cm^-2 s^-1 towards the substrate surface. The ion energy is low enough to prevent substantial ion-induced film damage, however the total energy flux provided to the substrate is sufficiently large to potentially stimulate the ALD surface reactions, e.g., through ligand desorption and adatom migration. Furthermore, it is demonstrated that the presence of VUV photons with energies of ~9.5 eV can deteriorate the electrical performance of electronic structures with ALD synthesized metal oxide films.
Enhanced Voltage Linearity of HfO2 Metal-Insulator-Metal Capacitors by H2O Prepulsing Treatment on Bottom Electrode
Authors: Lin Cheng-Ming , Chen Yen-Ting , Lee Cheng-Han , Chang Hung-Chih , Chang Wei-Chiang , Liu C. W.
Published: October 2010

The effects of H2O prepulsing treatments on the bottom Pt electrode of metal-insulator-metal (MIM) capacitors prior to HfO2 atomic layer deposition (ALD) were investigated for the first time. We demonstrated a MIM capacitor with capacitance density of 9 fF/μm2, quadratic voltage coefficient of capacitance (VCC) α of 499 ppm/V2 and low leakage current density of 5×10-8 A/cm2 at 1V. X-ray photoelectron spectroscopy (XPS) results reveal that the surfaces of the bottom Pt electrode were partially hydroxylated, which is considered as able to reduce the oxygen vacancies.
New Mechanisms for Ozone-Based ALD Growth of High-k Dielectrics via Nitrogen-Oxygen Species
Authors: Jung Sung-Hoon , Raisanen Petri , Givens Michael , Shero Eric , Delabie A. , Swerts Johan , Van Elshocht S. , Willem Maes Jan
Published: October 2010

Optimization of the O2/N2 feed gas flow during O3 generation by dielectric barrier discharge was found to improve the growth rate and uniformity of HfO2 and La2O3 films by atomic layer deposition (ALD) in a hot wall cross-flow thermal ALD reactor. Discharge products from the O3 generator and from the exhaust of the ALD reactor were analyzed by FTIR spectrometry. N2O, N2O5, NO2 and NO species were detected, as well as unreacted O3. Alternate models which could explain the behavior of various ozone-based ALD processes utilizing N2 doped O3 generation are presented.
Investigation of Volmer-Weber Growth during the Nucleation Phase of ALD Platinum Thin Films and Template Based Platinum Nanotubes
Authors: Shrestha Pragya , Gu Diefeng , Tran Ngoc , Tapily Kandabara , Baumgart Helmut , Namkoong Gon
Published: October 2010

Platinum thin films have been deposited by atomic layer deposition (ALD) using MeCpPtMe3 and oxygen as precursors. The nucleation phase of ALD Pt thin film deposition has been found to follow a Volmer-Weber island growth mechanism resulting in Pt nano dots and discontinuous films. Regular monolayer by monolayer ALD growth kicks in once the Pt film reaches a critical thickness of about 15 nm. Beyond the nucleation phase ALD Pt proceeds at a linear deposition rate of 0.5Aå/cycle. ALD growth of platinum was extended to nanoporous templates and platinum nanotubes were synthesized using porous alumina templates.
Deposition of Copper on Ruthenium for Cu Metallization
Authors: Kelly James , Van der Straten O. , Vo Tuan , Janek Richard , Dordi Yezdi
Published: October 2010

The morphology and behavior of thin Cu films deposited using electroless, electrolytic, and physical vapor deposition (PVD) is studied using Ru as a substrate. Ru was deposited by both PVD and atomic layer deposition (ALD). Electrolessly deposited Cu on PVD Ru resists agglomeration with annealing, while on ALD Ru it exhibits a tendency for agglomeration when annealed. Electrolytically deposited Cu on PVD Ru also resists agglomeration if the Ru to Cu plating queue time is short; on ALD Ru, it appears agglomerated as-deposited, even for short Ru to Cu plate queue times. In contrast to electrochemically deposited Cu, PVD Cu does not agglomerate with anneal on either PVD or ALD Ru, even for long Ru-Cu queue times. Auger spectroscopy suggests that ALD Ru has more oxygen and nitrogen at the surface as compared to PVD Ru. The possible roles of these impurities in impacting the deposited Cu morphology are briefly discussed.
(Invited) Plasma Enhanced Atomic Layer Deposition of TaN Films for Advanced Interconnects
Authors: Ma Paul , Lu Jiang , Aubuchon Joseph , Gung Tza-Jing , Chang Mei
Published: October 2010

The deposition of TaN thin films were achieved using plasma enhanced atomic layer deposition (PEALD) technique. In this paper, we demonstrate the ability to adjust film properties such as film composition, density and resistivity with various plasma conditions. The TaN films deposited by PEALD exhibited a lower resistivity of 200 - 500 μΩ-cm compared to thermally deposited ALD TaN films (> 1000.μΩ-cm). The density increases to 11-13 g/cm3 compared to 9 g/cm3 for thermal ALD films. The Cu diffusion barrier property of the PEALD films was superior to thermal ALD films. The application of the film in back end of line Cu interconnects will be discussed.
Plasma-Enabled ALD of Niobium Nitride Using an Organometallic Nb Precursor
Authors: Deguns Eric , Sowa Mark J. , Dalberth Mark J. , Bhatia Ritwik , Kanjolia Ravi , Moser Dan , Sundaram Ganesh M. , Becker Jill S.
Published: October 2010

NbN films were deposited via plasma-enabled ALD from (tBuN=)Nb(NEt2)3 and N2 plasma. A wide temperature process window (250-350°C) was demonstrated. Films had an atomic ratio of Nb:N0.9-0.95 and showed decreasing carbon contamination as the process temperature was increased.
Synthesis of NbN Thin Films for Superconducting Radiofrequency (SRF) Applications by Atomic Layer Deposition to Fabricate Superconductor-Insulator-Superconductor (S-I-S) Multilayer Structures
Authors: Gu Diefeng , Tapily Kandabara , Baumgart Helmut , Namkoong Gon , Crooks Roy
Published: October 2010

NbN thin films for superconducting radiofrequency (SRF) applications have been deposited by atomic layer deposition (ALD) from NbCl5 and NH3 as chemical precursors. Transmission electron microscopy reveals that the crystallization of the resulting NbN films is a sensitive function of ALD deposition temperature. Detailed X-ray diffraction (ARD) analysis demonstrated that the crucial superconducting cubic α' phase of NbN films has been achieved.
(Invited) ALD Moisture Barrier for Cu(InGa)Se2 Solar Cells
Authors: Carcia Peter F. , McLean Robert S. , Hegedus Steven
Published: October 2010

We report that gas diffusion barriers grown by atomic layer deposition (ALD) can protect moisture-sensitive, thin-film solar cells based on a Cu(In, Ga)Se2 absorber. The solar conversion efficiency for cells with ALD Al2O3 directly deposited, or laminated with a flexible polymer front sheet coated with an ALD barrier, was measured after stressing for more than 1000 hr in "damp heat" at 85{degree sign} C/85% RH with simulated solar illumination. For cells with ALD Al2O3 barriers, either directly deposited or laminated, the conversion efficiency decreased by only 3% after 1000 hr "damp heat" stressing. This supports ALD as an effective moisture-barrier strategy for extending the lifetime of flexible, thin-film CIGS solar cells, which are attractive for future building integrated applications.
(Invited) Atomic Layer Deposition on Polymers: Applications to Physical Encapsulation of Electrospun Nylon Nanofibers
Authors: Oldham Christopher J. , Gong Bo , Spagnola Joseph , Jur Jesse , Senecal Kris J. , Godfrey Thomas A. , Parsons Gregory N.
Published: October 2010

Nanofibers formed by electrospinning provide large surface areas which enable enhanced material performance in filtration and product separation. In this work, we explore atomic layer deposition (ALD) as a means to encapsulate and protect electrospun nylon-6 nanofibers. Exposing nylon to trimethyl aluminum (TMA) during ALD of aluminum oxide results in significant fiber degradation. Protecting fibers with a bilayer of ALD ZnO and an organic-inorganic hybrid polymer by molecular layer deposition maintains the shape of the original nanofibers, but chemical modification is still detected. These coating processes may help enable nanofibers with stable physical properties under chemical exposure.