bluuebunny/crossref_metadata_2025 huggingface dataset:
Coking Study in Anode Materials for SOFCs: Physicochemical Properties and Behavior of Mo-Containing Perovskites in CO and CH4 Fuels
Authors: Zheng Kun , Świerczek Konrad , Carcases Nahum Maso , Norby T.
Published: September 2014

Redox stable SrFe0.
75Mo0.
25O3-δ (SFM) and SrFe0.5Mn0.25Mo0.
25O3-δ (SFMM) anode materials show simple perovskite cubic structure in air, while SFMM transforms to B-site cation-ordered perovskite after reduction in 5 vol.% H2/Ar at 1100 °C. Over 2% mass changes were recorded for this materials during annealing in 5 vol.% H2/Ar atmosphere, indicating oxygen nonstoichiometry δ changes exceeding 0.2 mol·mol-1. Moreover, both oxides exhibit p-type conductivity in air, while n-type in 5 vol.% H2/Ar atmosphere. For 60 wt.% SFM and 40 wt.% CGO anode composite, no carbon deposition was observed in 10 vol.% CO/ CO2. In CH4 atmosphere, although coking occurs at 800 °C, usage of composite-type anodes with addition of CGO electrolyte can suppress the carbon deposition. Interestingly, no carbon deposition takes place at 600 °C for pure SFM, SFMM or composite anodes. The fuel gas composition and content of CGO in the anode material, as well as temperature significantly affect the coking issue.
Electrode/Electrolyte Interphase Studies of Ceria Based Electrolytes for IT-SOFCs
Authors: Baqué Laura Cecilia , Padmasree Karinjilottu , Fuentes Antonio F. , Serquis Adriana , Soldati Analía
Published: September 2014

Solid oxide fuel cells (SOFCs) require high operation temperatures (up to 800°C) in order to allow oxygen ion conduction through the ceramic electrolyte. Lowering SOFC operation temperature implies enhancing the transport and electrochemical properties of both electrolyte and cathode. In this work, the electrochemical performance of nanostructured La0.4Sr0.6Co0.8Fe0.2O3-d (LSCFO)/Ce0.8Gd0.2O2-d(CGO)/LSCFO and LSCFO/Ce0.8Nd0.2O2-d (CNO)/LSCFO symmetrical cells was investigated. The bulk conductivity is similar for both electrolytes, while the grain boundary and total conductivities is higher for the CGO electrolyte. Nevertheless, CGO electrolyte exhibits large pores that compromise its mechanical properties. In addition, cathode performance degrades in LSCFO/CGO/LSCFO cells.
Electronic and Morphological Characterization of Nanostructured Ni-Doped (Ce,Gd)O2-δ Anodes for IT-SOFCs
Authors: Fernandez Zuvich Afra , Soldati Analía , Larrondo Susana , Saleta Martín , Lamas Diego German , Baqué Laura Cecilia , Caneiro Alberto , Serquis Adriana
Published: September 2014

We present a new modified sol-gel method to incorporate Ni into the precursors solution. This route produces a powder with a very homogeneous Ni distribution as observed by Scanning electron microscopy (SEM). Transmission electron microscopy. (TEM) and Energy Dispersive Spectroscopy (EDS) analysis indicate that this modification resulted in smaller particle sizes with narrower distribution than the commercial cermet. The study of the oxidation state and coordination of Ce and Ni in these cermets, simulating in-operando conditions, is performed using synchrotron Dispersive X-ray absorption spectroscopy (DXAS) technique. A correlation between the catalytic/redox properties with the sample´s characteristics (microstructure, Ni distribution, etc.) is discussed.
Surface Exchange Model for MIEC Membrane in Transient Stage
Authors: Gazeau Camille , Blond Eric , Reichmann Mickael , Geffroy Pierre-Marie , Chartier Thierry , Richet Nicolas
Published: September 2014

Mixed Ionic and Electronic Conductors (MIECs) are promising membrane materials for oxygen separation from air at high temperature. The transient stage is critical due to the stress induced by the chemical and thermal strain. To predict this strain, the oxygen activity field through the membrane has to be known. While the diffusion is well described by the Wagner theory, no consensus has yet emerged regarding the surface exchange models proposed in the literature. Furthermore, these models describe the stationary state, and cannot be extended to the transient stage. A new macroscopic surface exchange model is proposed. This model takes into account the association/dissociation of oxygen and the high energetic cost of oxygen reduction/oxidation thanks to the balance of a transient species only present at the membrane surface. This model reproduces stationary and transient states
Improving the Activity and Stability of PdSn Catalyst for Oxygen Reduction by Heat Treatment
Authors: Salomé Sónia , Oliveira M.C. , Savadogo Oumarou , Rego Rosa
Published: September 2014

Carbon-supported PdSn catalysts were synthesized (ratio of about Pd:Sn = 1:1) by the NaBH4 reduction method for the oxygen reduction reaction (ORR) in HClO4 solution. The carbon support surface was previously activated with a sensitizing and activating pre-treatment. The as-prepared PdSn catalyst was then heat treated at 300 ºC in H2/N2 (3vol.% H2). The PdSn catalysts were characterized by SEM/EDX, XRD and TEM before and after the heat treatment. The electrochemical activity towards ORR was examined by cyclic and rotating disk electrode measurements and compared with that of Pd. The ORR catalytic activity of PdSn heat treated catalyst was about 25 and 4 times higher than that of as-prepared and Pd catalyst, respectively. Accelerated stability test (AST) by repetitive potential cycling indicated that PdSn heat treated was very stable in electrochemical environment.
Development of Pt-Co-Mn Ternary Alloy Catalyst for PEFCs
Authors: Ishida Minoru , Matsutani Koichi
Published: September 2014

In this study, PtCoX (X = Mn, Ni, Fe, Cr, Ti, Cu, Zn, Mo, V, Sn, In, Pd, Ir, Ru, Au) / High surface area carbon (HSAC) ternary alloys catalysts were synthesized and investigated about activity for the oxygen reduction reaction (ORR). PtCoMn / C showed the highest activity for ORR in all catalysts evaluated. XRD studies showed the formation of Pt3Mn and Pt3Co in the alloy structure by applying high temperature heat treatment. This result suggests that the mixture of Pt3Mn and Pt3Co alloys are highly active species for oxygen reduction reaction.
Design of Highly Durable Electrocatalyst for High-Temperature Polymer Electrolyte Fuel Cell
Authors: Fujigaya Tsuyohiko , Berber Mohamed Reda , Nakashima Naotoshi
Published: September 2014

We describe a polymer electrolyte fuel cell (PMFC) with an extremely high durability (single cell test: >400,000 cycling) together with a high power density (252 mW/cm2) at high temperature (120¢ªC) under a non-humid atmosphere. Such a high performance PMFC development opens the door for the next-generation PEFC for “real world” use. This is achieved by using a membrane electrode assembly (MEA) with poly(vinylphosphonic acid)-doped poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI)-wrapped carbon nanotube/Pt nanoparticles and poly[2,2’-(2,6-phenyl)-5,5’-bibenzimidazole] (PBI) for both the anode and cathode catalysts and an electrolyte membrane material, respectively.
Oxide-Based Electrocatalysts as Precious Metal and Carbon Free Cathodes for PEFC
Authors: Hamazaki Makoto , Ishihara Akimitsu , Arao M , Matsumoto M , Imai H , Kohno Yuji , Matsuzawa Koichi , Mitsushima Shigenori , Ota Ken-ichiro
Published: September 2014

Development of non-platinum electrocatalysts for oxygen reduction reaction (ORR) is required for real commercialization of polymer electrolyte fuel cells. We focused on high stability of group 4 and 5 metal oxide-based compounds in acidic media. In this study, in order to demonstrate superior durability of oxide-based cathodes, we prepared all oxide-based cathodes which were composed of magneli phase titanium oxide (Ti4O7) as electric conductive and Ti-Nb complex oxide with oxygen vacancies as active sites (Ti4O7-TixNbyOz). The ORR activity of the Ti4O7+TixNbyOz was higher than that of the Ti4O7, indicating that the active sites might be oxygen vacancies on the TixNbyOz. The onset potential of the Ti4O7+TixNbyOz was over 1.0 V vs RHE. No degradation of the ORR performance of the Ti4O7+TixNbyOz was observed during potential cycling from 1.0 to 1.5 V as degradation test. Therefore, we successfully demonstrated that the all oxide-based (carbon free) cathodes had high durability in high potential region.
Defective Nitrogen-Doped Graphene Foam: Clarifying the Role of Nitrogen in Non-Precious ORR Catalysts
Authors: Liu Jianfeng , Daio Takeshi , Sasaki Kazunari , Lyth Stephen Matthew
Published: September 2014

Iron-free, nitrogen-doped graphene foam is presented as a model electrocatalyst system for studying the role of nitrogen in the oxygen reduction reaction in non-precious Fe/N/C-based electrocatalysts. Due to the large surface area and high porosity, these electrocatalysts display high activity in rotating ring-disk electrode voltammetry measurements. The electron transfer number is as high as 3.6, despite the metal-free nature of this electrocatalyst. The sample with the highest activity has a significantly larger proportion of tertiary / graphite-like nitrogen, and therefore this is proposed as a 4-electron oxygen reduction active site in acid environment.
Thin-Film Non-Precious Metal Model Catalysts for Oxygen Reduction Reaction
Authors: Martinez Ulises , Williamson Todd L , Artyushkova Kateryna , Mack Nathan , Purdy Geraldine M , Dumont Joseph H , Kelly D , Gao W , Dattelbaum Andrew M , Mohite Aditya , Gupta Gautam , Zelenay Piotr
Published: September 2014

In this work, a novel systematic bottom-up approach in the investigation of the role of each component in non-precious metal ORR electrocatalysts is developed. Liquid-phase exfoliated graphite and graphene oxide were used as model two-dimensional carbon precursors. Nitrogen doping of these precursors was achieved via high-temperature ammonia treatment, as well as a novel technique of energetic neutral atom beam lithography/epitaxy (ENABLE), introduced for the first time. ENABLE offers the ability of working at high kinetic energies, overcoming high thermal limitation barriers, and allowing for direct chemical bond activation of graphitic systems at lower temperatures. The correlation of chemical-structure to ORR activity of these model nitrogen-doped systems was investigated using ultrathin film electrodes.
Structure Formation and Characterization of PEMFC Catalyst Layers Blended with Multi-Walled Carbon Nanotubes
Authors: Suzuki Takahiro , Hashizume Ryohei , Hayase Masanori
Published: September 2014

Different kinds of sub-micron structured carbon, which are carbon black and multi-walled carbon nanotubes (MWCNTs), were blended in catalyst ink to fabricate catalyst layers which differ in pore structure. Carbon black is used as catalyst support in the conventional catalyst layers and the porous structure strongly depends on its aggregate structure. MWCNTs have completely different structure with the carbon black in sub-micron scale. Therefore, two kinds of MWCNTs were blended with the platinum-supported carbon in the catalyst ink and the effects on the structure were investigated. The catalyst layer which contains MWCNT showed lower porosity, fewer micro-cracks and large pores than the conventional catalyst layer which was blended with carbon black. These characteristic porous structure affected cell performance and showed large voltage drop at high current density in its polarization curve.
Study of Azoles as Bifunctional Additives for Proton Exchange Membranes Melt-Processing from LSC and SSC Perfluorosulfonic Acid Ionomers
Authors: Mokrini Asmae
Published: September 2014

Azoles are investigated as potential bifunctional additives for proton exchange membranes (PEM) manufacturing through direct melt-processing of acidic ionomers. The additives selected are highly polar additives with relatively high boiling points that are expected to interact with the ion-rich aggregates that compose the nanophase separation in ionomers and act as plasticizers improving the viscoelastic behavior during melt processing. Long Side Chain (LSC) and Short Side Chain (SSC) Perfluorosulfonic acid (PFSA) based ionomers membranes have been prepared using a series of heterocyclic azoles, the study describes the properties of the obtained materials.
Graphene Oxide Membrane Fuel Cells: Utilizing of a New Class of Ionic Conductor
Authors: Bayer Thomas , Bishop Sean R. , Nishihara Masamichi , Sasaki Kazunari , Lyth Stephen Matthew
Published: September 2014

The characterization and application of graphene oxide membranes as fuel cell electrolytes is explored and presented. Morphology, chemical composition, mechanical and electrochemical properties of vacuum-filtration prepared graphene oxide membranes and their performance as fuel cell electrolytes are discussed. Our graphene oxide membrane fuel cell (GOMFC) showed a maximum power density of ~ 6 mW/cm2 at 30 °C. Power density exhibited a decrease with increasing temperature and operation time, possibly due to partial loss of oxygen through reduction, and a resulting decrease in water-mediated proton transport.
(Invited) Engineering Net Water Balance in Polymer Electrolyte Fuel Cells
Authors: LaManna Jacob M , Mench Matthew M.
Published: September 2014

The net water drag in a polymer electrolyte fuel cell is a result of a variety of transport processes. There is often a need to tailor the water balance to achieve higher performance under dry operating conditions. The motivation of this collected work is to understand the methods by which we can control the water transport in a PEFC via engineering of the components and architecture. Experimental and numerical models have been developed to measure and predict this, and various pathways for control of water storage and transport will be discussed. In particular, control of the micro and macroporous layer thermal and mass transport resistance, cell architecture, and microporous layer|catalyst layer interface will be shown to be capable of manipulating the net water storage and drag coefficient.
Influence of Hydrophobic Coating of Gas Diffusion Layers on the Performance and Water Transport inside PEFC
Authors: Biesdorf Johannes , Oberholzer Pierre , Schmidt Thomas J. , Boillat Pierre
Published: September 2014

In this paper, we present experimental results about the influence of hydrophobic coatings (PTFE) inside gas diffusion layers of polymer electrolyte fuel cells (PEFC). Four different cell configurations with different PTFE-loadings of the anode and cathode GDL are characterized with high resolution neutron radiography combined with a pulsed gas analysis (PGA). The experiments demonstrate that the coating level on the anode side does not have any significant influence on the cell performance, whereas the coating on the cathode side has a substantial impact on the performance and water accumulation.
A Comprehensive Single-Phase, Non-Isothermal Mathematical MEA Model and Analysis of Non-Isothermal Effects
Authors: Bhaiya Madhur , Putz Andreas , Secanell Marc
Published: September 2014

A comprehensive single-phase non-isothermal MEA model, accounting for all applicable heat sources, viz., entropic and irreversible heating associated with electrochemical reactions, ohmic heating, phase change, and heat release/absorption due to sorption/desorption of water in electrolyte is presented. The model accounts for water management in two phases, vapour and sorbed phase, and temperature driven vapour diffusion, and thermal osmosis. It is integrated into openFCST, an open-source fuel cell simulation framework. Maximum temperatures inside the cell rise by up to 12°C. A detailed breakdown of various heat sources inside the cell is studied. The heat of sorption, ignored in the literature, is more significant than protonic ohmic heating at medium currents and causes a shift in temperature distribution in the in-plane direction. Reversible heat distribution based on Ref. [1] resulted in temperature shifts with anode catalyst layer being the hottest.
Modelling and Measurements of Temperature Distributions inside MEA and Its Effects on Water Transport
Authors: Araki Takuto , Sugimoto Toshiki , Minegishi Yasuyuki , Higuchi Masaru
Published: September 2014

Polymer electrolyte fuel cell (PEFC) is one of the cleanest and most fuel saving energy conversion devices. For the optimal design of a PEFC reaction layer, the understanding of coupled phenomena consists of heat and mass transport and electrochemical reaction is essential. For the understanding, the thin film micro sensor array has been developed and the temperature distributions near reaction layer have been measured. Moreover, the numerical model has been developed and conducted to realize the conjugated problem inside reaction layer of PEFC.
Density Functional Theory Study of OH and CO Adsorption on the Pt2Ru3 Surface
Authors: Alam Md. Khorshed , Takaba Hiromitsu
Published: September 2014

In this work, we present results of periodic density functional theory study of the adsorption of carbon monoxide (CO) and hydroxyl (OH) on Pt2Ru3 alloy surface for different conformation of Pt and Ru. These results were compared with CO and OH adsorption on pure Pt and Ru surfaces. We find that the mixing of Pt by Ru leads to stronger bond of CO and OH to the Ru sites, whereas weaker bond notice of CO and OH to the Pt sites. We also analyze the effect of surface, sub surface and neighboring atoms effect on the adsorption of CO and OH on the Pt2Ru3 alloy surface. We notice that surface mixture with Pt and Ru atoms is more favourable adsorption sites for CO and OH than that of the homogeneous alloy surfaces.
Investigation of Performance and Durability of MEAs at Higher Temperature
Authors: Kitamura Masahiko , Minamida Yasuto , Zhao Xiaojing , Noda Zhiyun , Hayashi Akari , Sasaki Kazunari
Published: September 2014

For the application of polymer electrolyte fuel cell (PEFC) as a next generation fuel cell vehicle, an increase in the operation temperature up to 120 °C is desired in order to improve the power generation efficiency. The objective of our research is to extract problems on catalytic degradation above 100 °C with the aim of developing durable electrocatalysts for future high temperature PEFC. In this study, we have prepared standard membrane-electrode-assemblies made with Nafion® membrane and evaluated their durability against carbon oxidation in the cathode layer under increased temperature like 105 °C. As a result, comparing to the standard operation condition (80 °C and RH100%), the degradation rate of their electrochemical performance was much more increased at higher temperature. Furthermore, a collapsed carbon structure in the cathode layer was clearly observed under the high temperature operation.
PEMFC Cathode Contamination Evaluation with Membrane Conductivity Cell, CA, CP, CV, EIS, GC/MS and ISE - Acetonitrile
Authors: Zhai Yunfeng , St-Pierre Jean , Ge Junjie
Published: September 2014

Acetonitrile contamination in proton exchange membrane fuel cells (PEMFCs) was studied in situ with chronoamperometry, chronopotentiometry, cyclic voltammetry, electrochemical impedance spectroscopy, gas chromatography/mass spectroscopy, and ex situ with a membrane conductivity cell, ion selective electrode. PEMFCs significantly lost and partially regained performance for all tested electrodes. A significant effect on the membrane proton conductivity was noted in PEMFC but not in conductivity cells. The impact was dependent on the applied potential. Acetonitrile adsorption inhibits the hydrogen oxidation/evolution and the Pt oxidation and PtOx reduction reactions. Several peaks located at 0.17/0.22, 0.40/0.58, 0.65/0.78 V, and 0.9 V vs the hydrogen reference electrode were attributed to the redox of acetonitrile intermediates and products. Clear mechanistic insights were highlighted but a more complete integration of all these results and others obtained with a rotating ring/disc electrode (RRDE) will lead to a more definitive version of the acetonitrile contamination mechanism.
Cross-Sectional Visualization of Liquid Water Behavior and Evaluation of Wettability Effect in Cathode Channel of an Operating PEFC
Authors: Nishida Kosuke , Muranishi Toru , Ishizaki Yugo , Tsushima Shohji , Hirai Shuichiro
Published: September 2014

Water plugging in cathode channel of polymer electrolyte fuel cells (PEFCs) is recognized as a critical issue for high performance operation. In this study, the growth and attachment behaviors of liquid droplets and the removal of water plugs in the cathode channel of an operating PEFC were observed based on a cross-sectional visualization technique. Furthermore, the cell voltage and differential pressure between the cathode inlet and outlet were also monitored during cell operation, and the effect of surface wettability of channel wall on the water transport and cell performance was discussed. It was noted that hydrophilic treatment on cathode channel wall is effective in alleviating channel clogging and stabilizing cell performance.
Hydrogen Fuel Cells for Small Unmanned Air Vehicles
Authors: Swider-Lyons Karen , Stroman Richard O'Neil , Gould Benjamin D. , Rodgers Joseph A. , Mackrell Joseph , Schuette MIchael , Page Gregory
Published: September 2014

The Naval Research Laboratory has developed hydrogen fuel cell propulsion systems for unmanned air vehicles (UAVs). The high electrochemical conversion efficiency of fuel cells combined with the high specific energy of H2 fuel makes them suited to extending the endurance of small UAVs. The major consideration for UAVs is sufficient system level specific power (W/kg) for take off and high specific energy (Wh/kg) for long endurance. The high specific power is gained from using high power fuel cells and keeping components lightweight. The high specific energy comes from high weight fraction H2 fuel storage combined with a high efficiency fuel cell. The fuel cell air compressor and heat exchanger and the H2 storage system are major weight contributors, thus making them lightweight is critical to the vehicle design.
Impact of Water Flow Rate on Current Efficiency in Solid Polymer Water Electrolyzer Under 2 MPa Condition
Authors: Ito Kohei , Maeda Yusuke , Sakaguchi Takuya , Inada Akiko , Nakajima Hironori
Published: September 2014

When solid polymer water electrolyzer (SPWE) is operated under high pressure conditions, large pressure difference forms between anode and cathode. It causes crossover of produced gas, especially for hydrogen gas, and decreases current efficiency of SPWE. Supplying water into cathode channel, in addition to anode, is a countermeasure to suppress the crossover, because the water flow improves to drain the hydrogen gas outside of cell, resulting in a decrease of the crossover and increase of the efficiency. This countermeasure for the crossover is evaluated by a SPWE operation under 2 MPa condition with visualization of hydrogen bubbles in cathode channel. The evaluation revealed that supplying water into cathode channel increases the efficiency by several percent under 0.33 A/cm2. Enhanced detachment of hydrogen bubbles from the surface of current supplier was confirmed by the visualization. It is suggested that this enhancement increases the efficiency.
The Effect of Alloying in Pt-Sn/C Electrocatalysts in the Performance of a Direct Ethanol Fuel Cell
Authors: Colmati Flavio , Sousa Ruy , Ciapina Eduardo Gonçalves , Gonzalez Ernesto Rafael
Published: September 2014

Work on Pt-Sn-C catalysts for ethanol oxidation showed that a thermal treatment at moderate temperatures leads to a significant increase in activity. The best activity was observed for Pt3Sn1 thermally treated at 200 oC and ascribed to a Pt3Sn1 phase plus a cleaning effect. However, electronic effects may be very important and these were not evaluated in the Pt3Sn1 phase. Therefore, in this work we investigated the effect of the degree of alloy on the electronic structure of Pt3Sn1 electrocatalysts by performing electrochemical in situ X-ray absorption (XAS) experiments in the Pt LIII XANES region. Overall, the results show that although the occupancy of the Pt 5d band depends on the degree of alloy other factors, such as the presence of tin oxides/hydroxides in the materials, have to be considered to understand the performance of the DEFC.
(Invited) Double Salt Ionic Liquids Prepared by Mixing Partially Miscible Ionic Liquids: Tuning the Solubility of Lipophilic Molecules
Authors: Wang Hui , Pereira Jorge , Myerson Allan , Rogers Robin Don
Published: September 2014

Double Salt Ionic Liquids (DSILs) were prepared by mixing 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) and trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide ([P66614][NTf2]) in their miscible range: [C2mim]x[P66614](1-x)[NTf2] (0 ≤ x ≤ 0.29). 1H NMR, 19F NMR, and FT-IR spectroscopic studies indicated that the [NTf2]-anions preferentially interact with the [C2mim]+cations. Solubility studies showed that solutes with long alkyl chains (e.g., heptane, methyl palmitate), which have good solubility in [P66614][NTf2] but are not totally miscible, have tunable solubility in the DSILs and the presence of even minor amounts of [C2mim]+significantly decreases their solubility. However, the solubilities of benzene, toluene, 1-octanol, and poly(ethylene glycol) (PEG-300) in [C2mim]x[P66614](1-x)[NTf2] were controlled by their miscibility with [P66614][NTf2], and can’t be tuned by changing the ion concentrations within the miscibility range.
Binary Ionic Liquid Mixtures for Supercapacitor Applications
Authors: Lall-Ramnarine Sharon , Suarez Sophia , Zmich Nicole , Ewko Damian , Ramati Sharon , Cuffari David , Sahin Meriam , Adam Yara , Rosario Emely , Paterno Domenec , Wishart James
Published: September 2014

Binary mixtures of ionic liquids (ILs) were prepared and characterized to obtain ILs with viscosity and conductivity properties optimized for use in energy storage devices such as supercapacitors. The bis(trifluoromethylsulfonyl)amide anion (NTf2
-) was the common anion for both ILs in the mixture. Ethoxyethyl was the common substituent on the solute and solvent, as ether substituents have been shown to produce low viscosity ILs. N-Ethoxyethyl-N-methylpyrrolidinium NTf2 was used as the solvent for all of the IL mixtures. The solutes were either monocationic or dicationic and made up 10% of the binary mixture by weight. We report here on the physical properties of the individual ILs and their binary mixtures.
(Invited) Absorption of Flue-Gas Components by Ionic Liquids
Authors: Kolding Helene , Thomassen Peter , Mossin Susanne , Kegnæs Søren , Riisager Anders , Rogez Jacques , Mikaelian G , Fehrmann Rasmus
Published: September 2014

Gas separation by ionic liquids (ILs) is a promising new research field with several potential applications of industrial interest. Thus cleaning of industrial off gases seems to be attractive by use of ILs and Supported Ionic Liquid Phase (SILP) materials. The potential of selected ILs for absorption of NOX, CO2 and SO2 are demonstrated and the possible mechanism of absorption described on the molecular level. Special focus regards the interaction of the ILs with water vapor, which is an important feature in envisaged application of flue gas cleaning in power plants, waste incineration plants, cement and glass factories as well as on board ships.
Electrochemical Reaction of Tris(1,10-phenanthroline)Iron Complexes in Some Amide-Type Ionic Liquids
Authors: Katayama Yasushi , Yoshihara Mami , Miura Takashi
Published: September 2014

Electrode reactions of tris(1,10-phenanthroline)iron complexes, [Fe(phen)3]3+/2+, were investigated in some amide-type ionic liquids. The diffusion coefficients of [Fe(phen)3]2+ and [Fe(phen)3]3+ were smaller than those of tris(2,2'-bipyridine)iron complexes, [Fe(bpy)3]2+ and [Fe(bpy)3]3+, in each ionic liquid, reflecting the phen complexes are larger than the bpy complexes. The ratio of diffusion coefficient of the trivalent species to the divalent one for [Fe(phen)3]3+/2+ was smaller than that for [Fe(bpy)3]3+/2+, indicating the coulombic interaction between the charged species and the ions composing the ionic liquid is dependent on the charge densities of complexes. The rate constants for [Fe(phen)3]3+/2+ were close to those for [Fe(bpy)3]3+/2+, suggesting the outer components of reorganization energies for both complexes are similar to each other. On the other hand, the reaction entropies for [Fe(phen)3]3+/2+ were smaller than those for [Fe(bpy)3]3+/2+, reflecting the difference in the charge densities of complexes.
Computational Study of Structure, Dynamics and Spectroscopy of Ionic Liquids
Authors: Kim Hyung J , Dhumal Nilesh , Shim Youngseon , Kim Hyunjin
Published: September 2014

A brief account is given of recent computational studies of dielectric loss and IR spectroscopy of imidazolium-based ionic liquids. Their key spectroscopic features are analyzed and related to ionic liquid structure and dynamics to obtain molecular-level insights. A brief contact is made with available experimental results.
Electrochemical Investigations of Benzil in Nonaqueous Media
Authors: Cheek Graham T.
Published: September 2014

Benzil has been found to undergo two successive reversible one-electron redox processes in the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate (BMPY TfO). This behavior is observed due to the very low proton donating ability of the BMPY cation. Upon addition of acetonitrile, however, the second redox process becomes irreversible. The benzil dianion is evidently undergoing protonation by acetonitrile, and the resulting voltammogram is very similar to that in acetonitrile itself. The benzil dianion also undergoes protonation in adiponitrile.
Electrochemical Studies of Imidazolium Carboxylate Adducts in a Room-Temperature Ionic Liquid
Authors: Cheek Graham T. , Roeper Donald F. , Pearson Wayne , O'Grady William E.
Published: September 2014

The electrochemical reduction of carbon dioxide has been studied in the room-temperature ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ( BMPY TfO ). CO2 reduction occurs at the negative solvent limit of BMPY TfO; however, addition of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI BF4) to the solution results in an increase of the reduction current for the EMI cation, which occurs at a more positive potential than does CO2 reduction. These results indicate that the reduction product of EMI cation, probably a carbene, can catalyze CO2 reduction in BMPY TfO. Electrochemical responses for imidazolium carboxylates are similar to those for CO2 / EMI BF4 mixtures, supporting the carbene / CO2 interaction.
The Composition of the Second Coordination Sphere and Charge Transfer of the Nb(V)/Nb(IV) Redox Couple in Alkali Halide Melts
Authors: Popova Anna V. , Kremenetsky Vyacheslav G. , Kuznetsov Sergey A.
Published: September 2014

A study of the effect of the second coordination sphere on the standard rate constants of charge transfer (k
s) for the Nb(V)/Nb(IV) redox couple in chloride-fluoride and fluoride melts is presented. By using cyclic voltammetry, the following series of the standard rate constants of charge transfer has been experimentally determined: k
s (KCl) < k
s (CsCl) < k
s
(NaCl–KCl). Quantum-chemical calculations showed that charge transfer activation energies could actually change in a nonmonotonic manner in the sodium-potassium-cesium series, resulting in a nonmonotonic change of charge transfer of rate constants in chloride-fluoride melts. In pure fluoride melts, the following dependence of the standard rate constants has been obtained: ks
(CsF) < ks
(KF) < ks
(NaF–KF). It has been established that ks
tend to increase in response to both temperature increase and substitution of a glassy-carbon electrode for a platinum one.
Molybdenum(V) Species in Alkali Chloride Melts: An Electronic Absorption Spectroscopy Study
Authors: Kamalov Robert V. , Volkovich Vladimir A. , Ivanov Alexander B. , Vasin Boris D. , Griffiths Trevor R.
Published: September 2014

Electronic absorption spectra of solutions of molybdenum pentachloride in fused alkali chlorides were studied between 450 and 850 oC. LiCl-KCl, NaCl-CsCl, NaCl-KCl-CsCl eutectics and NaCl-KCl equimolar mixture were used as solvents. Although the experimental spectra contain only one broad band in the visible region, resolving the spectra into overlapping bands revealed two individual components under the experimental band. The ratio of intensities of the constituent bands depends on temperature and they are attributed to the absorption of MoCl6
- ion and MoCl5 molecular species. Spectroscopic parameters of MoCl6
- were determined and MoCl6
-↔MoCl5 equilibrium is discussed. Absorption spectra of gaseous MoCl5 were also recorded.
Physicochemical Properties of Nonvariant Compositions of Ternary NaF-LiF-LnF3 Systems (Ln = La, Nd)
Authors: Faidyuk Nataliya V , Savchuk Ruslan N , Omel'chuk Anatolii A
Published: September 2014

Differential thermal, X-Ray diffraction analyses, high-temperature X-Ray diffraction, thermo-electromotive force and viscosimetry has been used to study physicochemical properties of nonvariant compositions of ternary NaF-LiF-LnF3 systems (Ln = La, Nd).
(Invited) Electrorefining of Na in Hydrophobic Ionic Liquids
Authors: Ueda Mikito
Published: September 2014

Electrochemical reactions of metallic sodium were investigated in NaTFSI-TEATFSI ionic liquids and NaTFSI-TBATFSI ionic liquids at 433 K. Melting point of the ionic liquids was 309 K with lowest value in 20 mol% NaTFSI-TEATFSI. The maximum value of electrical conductivity was 36 mScm-1 at 20 mol% NaTFSI-TEATFSI from the impedance measurement. In the anodic polarization curves, a diffusion limit current was observed at -1.8 V vs. Na/Na(I) at the ionic liquid. Electrorefining experiments for 30 h were carried out at 433 K. After the electrorefining, metallic sodium of 99.99 % purity was obtained by the electrorefining.
Electrodeposition of Palladium in 1-Butyl-3-Methylimidazolium Chloride Ionic Liquid
Authors: Shrestha Sujan , Gjoka Eriugen , Biddinger Elizabeth J.
Published: September 2014

Pd electrodeposited in aqueous-based solutions suffer from hydrogen embrittlement which could be avoided using ionic liquids. Herein, electrodeposition of Pd in 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) was performed at 110 ºC. Three types of Pd species are found having distinct reduction potentials from cyclic voltammograms (CVs). On electroreduction by potentiostating in-situ etched Ni at -1.4 V vs Pd pseudo-reference electrode, Pd was deposited into flat structures. Energy dispersive spectroscopy (EDS) showed that the Pd deposits were strongly associated with carbon containing molecules. The carbon containing molecule is most probably strongly coordinating imidazolium cations.
A New Electrodeposition Process of Crystalline Silicon Utilizing Water-Soluble KF–KCl Molten Salt
Authors: Maeda Kazuma , Yasuda Kouji , Nohira Toshiyuki , Hagiwara Rika , Homma Takayuki
Published: September 2014

Toward the establishment of a new electrodeposition process of Si, the optimum conditions for obtaining adherent, compact and smooth Si film in molten KF–KCl–K2SiF6 were investigated. Galvanostatic electrolysis was conducted on an Ag substrate in eutectic KF–KCl (45:55 mol%) with various current densities (10–500 mA cm−2) and K2SiF6 concentrations (0.50–5.0 mol%) at 923 K. Cross-sectional SEM observation of the deposits revealed that compact and smooth Si films form at intermediate K2SiF6 concentration and current density. The morphology of the Si deposit changed into nodular at higher current density. At lower current density, detachment of Si layer from the Ag substrate occurred during the water washing. The relationship between the deposition conditions and Si morphology is discussed from the view point of electrodeposition mechanism.
Electrochemical Deposition of Alkali Metal in Low-Melting Alkali Metal Perfluorosulfonylamides
Authors: Kubota Keigo , Matsumoto Hajime
Published: September 2014

Low-melting alkali metal salts have possibility to be molten salt electrolytes for various applications. Depositions of alkali metal in the single molten salts, which correspond to their cathode limits, were investigated by cyclic voltammetry. For example, the single lithium (fluorosulfonyl)(trifluoromethylsulfonyl)amide molten salt showed a pair of reduction and oxidation currents on the nickel electrode at −0.02 V vs. Li+/Li. The order of deposition potential is Na > Li > K > Rb > Cs. This study is the first time for discussion about deposition in the single alkali metal perfluorosulfonylamides.
The Behavior of Additives LiF and KF on Current Efficiency in Aluminium Electrolysis
Authors: Cui Peng , Solheim Asbjørn , Haarberg Geir Martin
Published: September 2014

The effects of KF and LiF addition to the electrolyte on current efficiency were investigated during aluminium electrolysis using base NaF−AlF3−Al2O3−CaF2 system at 980°C in laboratory scale. The electrolysis was performed with a cryolite ratio of 2.5 and with 4% Al2O3 and 5% CaF2. The duration of each electrolysis experiment was 4 h with a graphite anode and a cathodic current density of 0.85 Acm-2. The current efficiency was found to vary with the lithium fluoride and potassium fluoride concentration.
An Electrochemical Study of Uranium (III) and (IV) Species in Fused Alkali Chlorides
Authors: Maltsev Dmitry S. , Volkovich Vladimir A. , Vladykin Evgeny N. , Vasin Boris D.
Published: September 2014

The behavior of uranium(III) and (IV) chloro-species was studied in LiCl-KCl-CsCl eutectic melt between 573 and 1073 K by potentiometry, cyclic voltammetry and chronopotentiometry. Uranium formal standard electrode potentials and U(III)/U(IV) formal red-ox potentials in the given melt were determined and thermodynamic properties of uranium chlorides calculated. Diffusion coefficients of U(III) and U(IV) ions were determined employing cyclic voltammetry and chronopotentiometry measurements.
Separation of Uranium and Lanthanides in a Fused Salt – Liquid Gallium Based Alloy System
Authors: Melchakov Stanislav Yu. , Maltsev Dmitry S. , Volkovich Vladimir A. , Yamshchikov Leonid F. , Osipenko Alexandr G.
Published: September 2014

The results of thermodynamic calculations of uranium and lanthanides (praseodymium and neodymium) and experimental data on separation of uranium and neodymium in “LiCl-KCl-CsCl-based melt – Ga-In eutectic based alloy” are compared. Additionally the results of calculations of separation of Pr/U and Nd/U couples using liquid gallium, indium and their eutectic alloy at 723, 773 and 823 K are presented.
Niobium Speciation in NaCl-KCl Based Melts: An Electrochemical and Spectroelectrochemical Study
Authors: Polovov Ilya B. , Chernyshov Mikhail V. , Shuklin Dmitriy A. , Volkovich Vladimir A. , Rebrin Oleg I. , Vasin Boris D. , Griffiths Trevor R.
Published: September 2014

A variety of electrochemical techniques (polarization curves measurements, chronopotentiometry, chronoamperometry, linear, cyclic and square-wave voltammetry, impedance spectroscopy) were applied for studying electrode processes involving niobium species in NaCl-KCl-based melts. Information about niobium speciation was obtained by combining electrochemical and spectroscopic (measuring electronic absorption spectra) methods. The major product of niobium anodic dissolution in chloride melts at current densities up to 40 mA/cm2 were niobium(III) species, NbCl6
3-. Soluble niobium(V) species, NbCl6
-, represented the highest oxidation state of niobium in NaCl-KCl melts. It was shown that oxidation of Nb(IV) ions, NbCl6
2-, proceeds in a single step. Cathodic reduction of niobium(IV)-containing melts on tungsten electrode at -1.55÷-1.6 V (vs. Cl-/Cl2) resulted in formation of niobium metal. Electrochemical and spectroelectrochemical data indicate that intermediate niobium(III) species can be formed during elecroreduction of NaCl-KCl-NbCln (n=3.8-4.1) melts.
(Invited) Applications of Ionic Liquids in Electrochemical Energy Conversion and Storage
Authors: Ma Jiwei , Seidl Lukas , Ju Wenbo , Mostafa Ehab , Asen Ludwig , Martens Sladjana , Stimming Ulrich , Schneider Oliver
Published: September 2014

Ionic liquids have found widespread applications in electrochemistry, and are increasingly used in the field of electrochemical energy conversion and storage. In battery technology, the use of ionic liquids can increase the device safety significantly and help in enabling alternative technologies like Mg ion batteries. In fuel cell technology, new, water-free proton conducting membranes and new options for synthesis and improvement of catalysts are in the focus of research. In this paper some applications, advantages and drawbacks of ionic liquids in electrochemical energy technology are reviewed. Some examples from the authors’ own work in batteries and electrocatalysis using standard electrolytes are presented, and the potential improvements by using ionic liquids in these studies are discussed.
Inorganic-Organic Hybrid Ionic Liquid Electrolytes for Na Secondary Batteries
Authors: Matsumoto Kazuhiko , Taniki Ryosuke , Nohira Toshiyuki , Hagiwara Rika
Published: September 2014

Physical and electrochemical properties of the three inorganic-organic hybrid ionic liquid electrolytes for Na secondary batteries (Na[FSA]-[TMHA][FSA], Na[FSA]-[DBDM][FSA], and Na[FSA]-[[AS[4.5]][FSA], where TMHA+ = trimethylhexylammonium cation, DBDM+ = dibutyldimethylammonium cation, AS[4.5]+ = 5-azoniaspiro[4.5]nonane, and FSA− = bis(fluorosulfonyl)amide anion) have been investigated. In all the three systems, the liquid phase is observed at room temperature in a certain range of Na[FSA] fraction. Ionic conductivity and viscosity of the three systems obey the VTF equations and the highest ionic conductivity is observed for the Na[FSA]-[[AS[4.5]][FSA] in the present series. Their electrochemical windows are ~5 V and Na metal electrodeposition/dissolution are observed around 0 V vs. Na+/Na.
Zn-Sn Electrochemical Cells with Molten Salt Eutectic Electrolytes and Their Potential for Energy Storage Applications
Authors: Holubowitch Nick , Manek Stephen , Landon James , Lippert Cameron , Odom Susan A , Liu Kunlei
Published: September 2014

Molten salts at moderate temperatures (ca. 460-690 K) are investigated as electrolytes in two different electrochemical cells employing Zn and Sn electrodes. The thermodynamics and kinetics are explored in an H-cell design, as an analogue to the conventional galvanic cell, and in a one pot, membrane-free system. Emf-temperature measurements reveal opposing trends between the two designs owing to different redox chemistry at the cathode. The potential of these systems for electrochemical energy storage applications are considered. The simpler, membrane-free design is able to deliver the highest short-circuit current densities due to lower Zn activity in a molten ZnSn alloy.
Indirect Methods of Determination of K:Al Mole Ratio in Molten Chloroaluminates
Authors: Karpov Vyacheslav V. , Polovov Ilya B. , Kudryashov Dmitriy , Lisienko Dmitriy G. , Volkovich Vladimir A. , Chukin Andrey V. , Rebrin Oleg I.
Published: September 2014

Indirect methods for determining K : Al mole ratio in molten chloroaluminates were proposed to obtain correct data and perform possible required adjustment of the acid-base properties of KCl-AlCl3 electrolytes. Potentiometric calibration curves for different compositions of chloroaluminate melts were obtained at temperatures ranging from 350 to 450 oC. It is shown that cyclic voltammograms measured in melts with different K : Al mole ratios also can be used for estimating acidity/basicity of KCl-AlCl3 melts. Full profile Rietveld analysis of X-ray diffraction patterns was suggested for characterization of quenched chloroaluminate electrolytes.
(Invited) Use of Fluorescence Imaging and Ionic Liquids in the Study of Carbon, Clay, and Cellulose Based-Nanomaterials
Authors: Gilman Jeffrey W.
Published: September 2014

Some of the most critical issues facing the nanocomposite community include the need for multi-scale imaging of hierarchical structures, effective methods for controlling nanoparticle chemistry and surface-energy, and efficient processing methods for preparing nanoparticles and nanocomposites. Over the last decade we have employed a number of approaches to address some of these challenges. This paper will review our efforts centered on the use of ionic liquids and fluorescence microscopy to develop tools to enable industry to more quickly bring new nanocomposite-based products to market. Research results focused on polymer nanocomposite based on multiwalled-carbon-nanotube (MWCNT), Montmorillonite (MMT) and nanofibrillated-cellulose (NFC) will be presented.
Inkjet Printing Ionic Liquids for the Fabrication of Surface Structures on Biopolymer Substrates
Authors: Sweely Kurt D. , Fox Eric T. , Brown E. Kathryn , Haverhals Luke M. , De Long Hugh C. , Trulove Paul C.
Published: September 2014

Data describing the effects of an inkjet-printed ionic liquid (IL) ink containing 1-ethyl-3-methylimidazolium acetate ([EMI][OAc]), with microcrystalline cellulose (MCC) and carbon black (CB) additives are presented. Scanning electron microscopy (SEM) and confocal fluorescent microscopy (CFM) are used to observe the efficacy of inkjet printing of IL inks for surface modification of cellulosic substrates. SEM micrographs of printed IL-MCC ink, with and without heat treatment, revealed the creation of individually-coated fibers or thin polymer films, respectively. Micrographs of printed IL-CB ink demonstrate the capabilities of IL-based inks to deposit and entrap micro-scale functional materials in the substrate matrix with good localization and resolution. CFM analysis of samples containing 5-DTAF-labelled MCC (0.5 wt.%) further demonstrates the regioselectivity and low mobility of inkjet-printed IL inks once printed onto substrates. Together, these data demonstrate the enormous capability of inkjet-printed IL inks for small-scale fabrication of devices and functional cellulose-based materials.
(Invited) An Overview of the REFINE Project --- The Sustainable Reduction of Spent Fuel Vital in a Closed Loop Nuclear Energy Cycle
Authors: Hu Di , Stevenson Anthony , Chen George Zheng
Published: September 2014

Nuclear fission is perhaps the most controversial, alongside renewables and clean coal, as one of the “trinity” of fuel option for future UK supply. A pressing need for the development of safe, reliable, economic and sustainable nuclear energy on the scale is required in both the short and long term. Therefore, a coordinated materials programme for the sustainable REduction of spent Fuel vital In a closed loop Nuclear Energy cycle (REFINE) has been established to fulfill these requirements. This is a multidisciplinary, multi-institutional programme involving the Universities of Edinburgh, Nottingham, Cambridge and Manchester, University College London, and the National Nuclear Laboratory. The REFINE project aims to address the research challenges in legacy waste clean-up, fuel decommissioning and disposal, and specific spent fuel reprocessing technology suitable for Gen III+ and Gen IV reactor systems.
Selective Formation of Rare Earth-Nickel Alloys via Electrochemical Reactions in NaCl-KCl Molten Salt
Authors: Yasuda Kouji , Kondo Katsuya , Kobayashi Seitaro , Nohira Toshiyuki , Hagiwara Rika
Published: September 2014

Toward the establishment of the electrochemical recovery process of rare earth elements from used magnet scraps, selective electrochemical formation of RE–Ni alloys (RE = Nd, Dy, and Pr) was investigated in molten NaCl–KCl added with NdCl3, DyCl3, and PrCl3 (0.50mol% each) at 973 K. Alloy samples were prepared by potentiostatic electrolysis using Ni plate electrodes at various potentials. Compositions of the formed alloys were analyzed by EDX, and separation factors defined as x
Dy/(x
Nd + x
Pr) were compared. High separation factors of 9.9 and 22.9 were obtained at 0.42 V and 0.45 V (vs. Na+/Na), respectively, indicating the possibility of effective separation and recovery of REs from the used magnet scraps.