bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPARATIVE STUDY ON THE ADSORPTION PROCESSES OF ALKANETHIOL AND ALKANEDITHIOL ON GOLD
Authors: HE HUI , GUO YAN , WANG SHOUFU , JIANG YAQING
Published: March 2011

The kinetics of formation of self-assembled monolayers on gold generated by the adsorption of 1-octanethiol and 1,8-octanedithiol were explored by electrochemistry measurement. The time dependence of capacitance and surface coverage supported that the adsorption of thiols typically processed with a two-step adsorption consisted of a fast initial adsorption and a slowly following reorganization. From the function of surface coverage versus time, one could get rate constants of adsorption of thiols, and the adsorption process was demonstrated to follow a diffusion-controlled Langmuir model. A comparison of the adsorption rates for different concentration between 1-octanethiol and 1,8-octanedithiol revealed that their adsorption processes were almost identical and independent on the concentration, inferring that only one sulfur atom contributed to the self-assembly of dithiol molecule.
FORMATION, STRUCTURE AND PROPERTIES OF HIGHLY ORDERED SUB-30-nm PHASE CHANGE MATERIALS (GST) NANOPARTICLE ARRAYS
Authors: LIAO YUANBAO , WU JIAJIA , XU LING , YANG FEI , LIU WENQING , XU JUN , WU LIANGCAI , MA ZHONGYUAN , CHEN KUNJI
Published: March 2011

Chalcogenide phase change material Ge1Sb2Te4 (GST) nanoparticle arrays with long-range-order were fabricated by using a monolayer of self-assembled polystyrene (PS) spheres as mask. The morphology of nanoparticle arrays can be controlled via changing RIE processing conditions. Images of atomic force microscopy (AFM) and scanning electron microscopy (SEM) show that highly uniform GST nanoparticle arrays with particle density around 109 cm-2 were formed. The sizes of nanoparticles can be reduced to a tiny diameter in the range of 30–40 nm (top diameter). The GST nanoparticle arrays exhibit a prominent peak near 580 nm in reflectance spectra, which indicates that they possess a photonic band gap. These results confirm that GST nanoparticle arrays have a 2D periodicity and long-range order. The method of nanosphere lithograph may apply to manufacturing of high density memory devices based on phase change-based memory materials.
INVERTIBLE COMMUTATORS IN MATRIX RINGS
Authors: KHURANA DINESH , LAM T. Y.
Published: March 2011

In a matrix ring R = 𝕄2(S) where S is a commutative ring, we study equations of the form XY - YX = U ∈ GL 2(S), focusing on matrices in R that can appear as X or as XY in such equations. These are the completable and the reflectable matrices in R. For matrices A ∈ R with a zero row or with a constant diagonal, explicit and "computer-checkable" criteria are found for A to be completable or reflectable. A formula for det (XY - YX) discovered recently with Shomron connects this study to diophantine questions about the representation of units of the ground ring S by quadratic forms of the type px2 + qy2.
The quest for randomness
Authors: Anthes Gary
Published: March 2011

It's not easy to generate a string of numbers that lack any pattern or rule, or even to define exactly what randomness means.
Reflecting on the DARPA Red Balloon Challenge
Authors: Tang John C. , Cebrian Manuel , Giacobe Nicklaus A. , Kim Hyun-Woo , Kim Taemie , Wickert Douglas "Beaker"
Published: March 2011

Finding 10 balloons across the U.S. illustrates how the Internet has changed the way we solve highly distributed problems.
Crowdsourcing systems on the World-Wide Web
Authors: Doan Anhai , Ramakrishnan Raghu , Halevy Alon Y.
Published: March 2011

The practice of crowdsourcing is transforming the Web and giving rise to a new field.
Reaching future computer scientists
Authors: Morreale Patricia , Joiner David
Published: March 2011

Think teachers, not students.
CS Ed Week activities survey
Authors: Joyce Dan
Published: March 2011

SIGCSE asked its members to share what they had planned for CS Ed Week. Many great activities were reported and we describe a few below. Something that many departmental activities had in common: pizza and cake! For a complete list of member events check out our website: http://sigcse.org/events/week.
Electrodeposition and Electroless Deposition of Metallic Powders: A Comparison
Authors: Djokić Stojan , Nikolić Nebojsa , Živković Predrag , Popov Konstantin , Djokić Nada
Published: March 2011

Electrodeposition and electroless deposition of metallic powders were comparatively investigated. Electrodeposition of copper is accompanied with the simultaneous hydrogen evolution, which significantly influences the morphology of Cu powder. At lower overpotentials, branched dendrites were produced. At higher overpotentials honeycomb-like deposits of copper were obtained. Formation of silver powders was characterized by the comparison of the exchange and limiting current densities. Instantaneous growth of dendrites starts at low overpotential due to large exchange current density in silver nitrate solution. Formation of powders such as Ni, Co, Ag, Pd and Au from homogenous solutions using an appropriate reducing agent or via galvanic displacement reaction was demonstrated. The hydrolysis of metallic ions is crucial in the deposition metallic powders via electroless deposition from homogenous solutions. Oxides, such as Ag2O, Cu2O and CuO, suspended in water can successfully be reduced with an appropriate reducing agent, leading to the precipitation of metallic powders.
Silver-Assisted Etching of Silicon Nanowires
Authors: Gielis Sven , Van der Veen Marleen , De Gendt Stefan , Vereecken Philippe M.
Published: March 2011

Silicon nanowires are attractive for photovoltaic applications where they can be used along with bulk silicon in an all-Si tandem solar cell. The larger band gap, caused by the quantum confinement effect in narrow silicon nanowires (< 5 nm), provides a more efficient light absorption. Most common processes for nanowire synthesis are rather expensive and require high temperatures, high vacuum and hazardous precursors. A simple and cheap method is the silver-assisted electroless Si etching process. Silicon is selectively etched in HF based solutions with help of silver particles which are deposited beforehand or in-situ. Both the etch process and the deposition of silver particles were studied. The silver nanoparticles were deposited by electroless deposition (galvanic displacement) from HF and non-HF containing solutions. The effects of silver coverage, Si doping and illumination on the Si etching process were investigated. The experimental observations were used to get more insight into the mechanism.
Galvanic Displacement of Nanostructured Gold for Flavoenzyme Adsorption in Biotechnology
Authors: Magagnin Luca , Cojocaru Paula , Raygani Anahit , Brivio Daniele , Secundo Francesco , Turolla Alessio , Ottolina Gianluca
Published: March 2011

Sensors are the devices which are composed of an active sensing material with a signal transducer. The recent development in the nanotechnology has paved the way for large number of new materials and devices of desirable properties which have useful functions for numerous electrochemical sensor and biosensor applications. In this work, results on the galvanic displacement of gold on silicon in different electrolytes will be presented. The growth of the gold films is characterized and the interfacial behavior with the substrate is characterized by microindentation in order to highlight the adhesion as a function of the electrolyte. Results on high surface area gold nanostructures on silicon will be presented. Such films will be tested and surface morphology will be correlated to the adsorption of flavoenzymes.
Well Ordered Hollow Urchin-Like ZnO by Electrodeposition
Authors: Elias Jamil , Lévy-Clément Claude , Bechelany Mikhael , Michler Johann , Philippe Laetitia
Published: March 2011

Increasing the aspect ratio of ZnO nanostructures is one possible strategy to improve their physical properties. ZnO nanostructures with 1D and 3D morphologies were obtained using electrochemical deposition. Playing with various deposition parameters enabled to obtain arrays of vertically aligned ZnO nanowires (NWs) with controlled dimensions, density and electrical properties. The concentrations of zinc or chloride ions in the solution were found to be major parameters to monitor them. ZnO-NWs were transformed into nanotubes (NTs) with an increased aspect ratio compared to the NWs, by selectively dissolving the core of the ZnO-NWs in a highly concentrated KCl solution. The aspect ratio was strongly increased, when the ZnO-NWs were hierarchically organized into 3-D morphology. The synthesis of thin films composed of ordered hollow urchin-like ZnO-NWs was performed by combining the electrochemical deposition and a polystyrene sphere template.
(Invited) Localized Breakdown of the Natural Oxide Film on Aluminum by Chloride Ions and the Formation of Oxide Blisters
Authors: McCafferty Edward , Natishan Paul M.
Published: March 2011

A sequence of events is discussed for the initiation and propagation of corrosion pits on aluminum in chloride solutions. Corrosion pit initiation takes into account adsorption of chloride ions on the oxide surface, penetration of chloride ions through the oxide film, and localized dissolution of aluminum at the metal/oxide interface. Corrosion pit propagation involves formation of blisters beneath the oxide film due to localized reactions which produce an acidic localized environment. The blisters subsequently rupture due to the formation of hydrogen gas in the occluded corrosion cell. Calculation of the local pH within a blister from the computed hydrogen pressure within the blister gives pH values in the range 0.85 to 2.3.
Direct Electropolymerization of Copolymer Electrolyte into 3D Nano-Architectured Electrodes for High-Performance Hybrid Li-ion Macrobatteries
Authors: Kyeremateng Nana Amponsah , Dumur Frederic , Knauth Philippe , Djenizian Thierry
Published: March 2011

It is shown that electropolymerization can be addopted to deposit a a copolymer electrolyte (PEO-PMMA) into titania nanotubes for the fabrication of on-chip microbatteries. The copolymer embedded TiO2 nanotubes shows good electrochemical performance, which is due to the electrode/electrolyte interface achieved by filling the nanotubes with the copolymer. The titania nanotubes and the copolymer-embedded nanotubes are characterized by surface analysis techniques including (SEM, EDX, FTIR and XPS). This electrolyte deposition process can be extended to any kind of 3D nano-architectured electrodes. The electrochemical performance was evaluated in lithium test cells.
Electrodeposited Metallic Nanowires as a Scanning Probe Tip
Authors: Motoyama Munekazu , Prinz Friedrich
Published: March 2011

This paper describes the production technique for metal-nanowire-AFM probes. Electrochemical deposition into nanoporous membranes grows metal nanowires with as small diameters as 15 nm. Free-standing-Ni wires with 15 nm and 100 nm diameters were successfully electrodeposited at the tips of AFM probes by electrodeposition.
Nanopore Morphology Development during Current Oscillations at the Si/Electrolyte Contact
Authors: Grzanna Juergen , Notz Thilo , Stempel Thomas , Lewerenz Hans J.
Published: March 2011

The development of nanopore morphology at the Si/electrolyte contact is considered during the anodic oxidation of n-type silicon in fluoride containing solutions. The applied morphological model is characterized by stress in silicon and cracks and nanopores in silicon oxide. We present the "Thickness Oscillator Model" in macroscopic and microscopic formulation. For the temporarily resolved macroscopic model, a relation between the integral equation used for calculation of the so-called synchronization states and the Helmholtz differential equation is presented. The nanopore morphology during current oscillations is measured by high resolution scanning electron microscopy and calculated using the microscopic model in the form of a spatio-temporarily resolved two-dimensional cellular automate. Two types of silicon oxide with different nanopore densities are visible which are shown to be the physical origin of the synchronization of the oscillations.
Photoelectrical Properties of a-Si:H Thin Films Deposited on Porous Silicon by DC-Magnetron Sputtering
Authors: Hamadache Farida , Zougar Lyes , Mokeddem Kamel , Brighet Amer , Gelloz Bernard
Published: March 2011

The Photoelectrical properties of hydrogenated amorphous silicon thin films (a-Si:H) deposited on porous silicon (PSi) were investigated. Porous Si layers were formed by electrochemical etching of p+-type crystalline Si in a hydrofluoric solution, whereas a-Si:H films were deposited in a partially hydrogenated atmosphere using the DC-Magnetron sputtering method. Samples with a-Si:H films deposited at different H2 flow rates and with PSi layers of different porosities and thicknesses were characterized. The Dark and under illumination I-V characteristics as well as the photocurrent response of these samples, were recorded on Al/a-Si:H/PSi/Si structures using both sandwich and planar configurations. These measurements were compared to that obtained with a-Si:H directly in contact with c-Si substrate. The results of our investigation demonstrate that the PSi layer characteristics strongly affect the photoelectrical properties of a-Si:H thin films and their influence depends on the electrical properties of these films.
Peptide Nucleic Acids in Dye-Sensitized Solar Cells - Functional Component, and Structural Component to Immobilize Silver Nanoparticles
Authors: Loew Noya , Ikenouchi Shun , Ihara Manabu
Published: March 2011

Dye-sensitized solar cells (DSSCs) containing silver nanoparticles (AgNPs) and peptide nucleic acids (PNA) were successfully fabricated. In DSSCs, PNA can be used as a structural component for immobilizing AgNPs on the TiO2 layer and as a functional component without AgNPs. For immobilizing AgNPs on the TiO2 layer by PNA hybridization, short PNA (10mer) with a 7 bp hybridizing sequence and an estimated total length of 3.2 to 4.2 nm was more suitable than long PNA (18mer). PNA was also used as a functional component and the internal quantum efficiency of DSSCs was successfully increased by more than 10 % (from 73 % to 88 %) by using double-stranded long PNA. Because PNA also reduces the light absorption of the photoabsorbing layer, however, the external quantum efficiency could not be increased with the used conditions.
STEP (Solar Thermal Electrochemical Production) of Energetic Molecules: A synergy of photovoltaics and solar thermal to form a new, higher efficiency solar energy process
Authors: Licht Stuart
Published: March 2011

STEP, Solar Thermal Electrochemical Production, provides an advance in solar energy conversion efficiency through the use of the full solar spectrum to generate energy rich chemicals. The process captures solar energy with conversion efficiency greater than that of photovoltaics, and rather than electricity, produces the chemical products needed by society. This original process is derived and demonstrated for the solar production of energetically rich chemicals, including iron, and hydrogen fuel without the evolution of carbon dioxide, and to proactively convert and capture anthropogenic CO2 generated in burning fossil fuels. The STEP process distinguishes radiation that is energy sufficient to drive photovoltaic charge transfer, and applies all excess energy to heat and decrease the energy of endothermic electrolysis reactions. Energy sufficient, visible, sunlight drives photovoltaic charge transfer, and available heat, infrared sunlight, and excess visible sunlight, heats, and decreases the energy of, an electrolysis reaction.
ZnO Buffer Layers and Nanowires Electrodeposition for Extremely Thin Absorber Solar Cells
Authors: Sanchez Sylvia , Salazar Raul , Lévy-Clément Claude , Ivanova Valentina
Published: March 2011

In this manuscript we are reporting on the electrodeposition of ZnO nanowires on potentiostatically and galvanostatically prepared ZnO 2D layers (called buffer layers) on glass substrates covered with transparent conductive oxide (TCO). It is shown that the buffer layer morphology and thickness could be used as parameters to control the ZnO nanowires dimensions. From the other side the supporting electrolyte concentration and the passed charge density during the electrodeposition are also playing role on tailoring their dimensions. The obtained nanowires exhibit interesting optical and structural properties and therefore they could be further used as nanostructured transparent n-type semiconductor for the extremely thin absorber (eta) solar cells, dye sensitised solar cells or hybrid polymer solar cells.
Photoluminescence Characterization and Passivation of CIGS Absorber
Authors: Cheng Tzu-Huan , Hsu W. W. , Huang C.Y. , Lu J.-A. , Chen J. Y. , Liu C. W.
Published: March 2011

The photoluminescence is used to monitor the optical property of the Cu(In,Ga)Se2 solar cell. The temperature dependent external quantum efficiency shows the influence of defects in optical response and the band gap shift of Cu(In,Ga)Se2 at elevated temperature. The emission peaks at 1.03 and 1.1 eV are due to electrons in conduction band edge and donor state to recombine with holes in acceptor state, respectively. Competitiveness of these two transition mechanisms is studied with different pumping power and varied temperature by photoluminescence. The defect level and relative defect density can be obtained by the transition models. The Al2O3 is used to passivate the surface of CIGS absorber and enhance the photoluminescence intensity.
Negative Resistances and Inductances in Equivalent Circuits for Adsorption-Reaction Kinetics
Authors: Srinivasan Ramanathan
Published: March 2011

The origin and nature of inductive arcs in electrochemical impedance spectra of reacting systems have been debated in the literature. In this work, inductances are shown to be an essential component in the electrical equivalent models of adsorption-reaction kinetics. An example reaction with one adsorbed intermediate species is analyzed in detail. The analysis is extended for a few other cases including second order reaction to show that the arguments are also applicable for more complicated cases. Similarly reactions with two adsorbed intermediates are analyzed and the applicability of resistances and inductances to model the system is confirmed. Even in the cases where the low frequency impedance appears to be capacitive, a negative inductance is shown to be a more appropriate choice than a capacitance. The physical basis of the origin of the inductances, negative inductances and negative resistances are discussed.
Analysis of Copper Dissolution in Glutamic Acid and Hydrogen Peroxide Using EIS
Authors: Srinivasan Ramanathan , Selvam Noyel Victoria
Published: March 2011

The dissolution of copper in solutions containing Glutamic acid and hydrogen peroxide is analyzed using EIS. Potentiodynamic polarization studies show that there is no strong passivating layer formed on the copper surface in solutions containing 0.5 wt% Glu and 0.1 vol% hydrogen peroxide. Electrochemical impedance spectra of copper in this solution at various overpotential were acquired and modeled using electrical equivalent circuit and reaction mechanism analysis. The results show that the reaction involves at least two adsorbed intermediates.
Preparation of LiFePO4 by Nozzle-Spray-Pyrolysis
Authors: Juestel Manuela , Schwinger Albrecht , Weiss Martin , Binnewies Michael
Published: March 2011

The olivine structured lithium iron phosphate LiFePO4 is a promising candidate for next generation lithium-ion-batteries. The main advantages of this material are its potentially low cost, its high safety and the fact that it is environmentally friendly. In this paper we present the synthesis and characterization of LiFePO4 prepared by nozzle-spray-pyrolysis. This synthesis technique allows the formation of spherical, non agglomerated particles with a narrow size distribution. Depending on the process parameters hollow shells or entirely solid particles can be obtained.
Controlled Synthesis of ZnO Nanospheres Using Hydrothermal Process
Authors: Foe Kurniawan , Boland Patrick M. , Gu Diefeng , Baumgart Helmut , Abdel-Fattah Tarek M. , Jeong Mun , Namkoong Gon
Published: March 2011

A novel, versatile, and template-free method has been developed to synthesize solid crystalline zinc oxide (ZnO) spheres via hydrothermal process at a temperature of 100oC within 2h. Using an aqueous solution of zinc acetate dihydrate, ammonium hydroxide, ethanol, and urea, the effects of pH values and structure directing agents on the morphology of ZnO crystals were systematically investigated. We found that the key parameters affecting ZnO morphologies are the pH value of the solution as well as the structure directing agents. When the structure directing agents such as ethanol and urea were used, at a pH value of 12, isotropic growth of ZnO spheres was developed, while at pH value less than 12, anisotropic growth of ZnO structures was observed. Furthermore, by modulating the volume ratio of ethanol in the solution, the size of the ZnO spheres could be controlled from nanometer to micrometer range.
Electrochemical Characterization of SEI-Type Passivating Films Using Redox Shuttles
Authors: Tang Maureen H. , Newman John
Published: March 2011

Although redox shuttles have been demonstrated to provide overcharge protection for up to 200 cycles, the existence of the solid-electrolyte-interphase (SEI) seems to be inherently incompatible with a successful shuttle reaction. The apparent selectivity of the SEI remains largely unaddressed in literature and provides an interesting method of studying this poorly understood subject. In this work, the kinetics of ferrocene, a model redox shuttle, is measured in the presence and absence of passivating films using rotating-disk-electrode voltammetry. A simple model of Butler-Volmer kinetics with a through-film limiting current fits the steady-state current-voltage curve. The presence of the film decreases both the limiting current and effective rate constant. Both parameters decrease with increased passivation time; a decreasing porosity is a possible explanation for this observation. The characterization method developed in this work allows direct measurements of the effect of passivating films, thus contributing to understanding of passivation phenomena in nonaqueous electrolytes.
Polyelectrolyte Membranes Containing Lithium Malonato(difluoro)borate for Lithium-Ion Systems
Authors: Driscoll Peter F. , Yang Li , Gervais Matthieu , Kerr John B.
Published: March 2011

A new salt, lithium malonato(difluoro)borate (LiMDFB), and two similar analogues, were synthesized and incorporated into polymer electrolyte membranes to investigate the bulk and interfacial properties as both a binary salt system and a single-ion conducting electrolyte for lithium ion batteries. Symmetric lithium/lithium cells were assembled with membranes composed of polyethylene oxide (PEO) doped with LiMDFB analogues along with LiTFSI for comparison. Conductivities and exchange current densities were determined from electrochemical impedance spectroscopy measurements and the interfacial impedance was shown contribute significantly to the overall impedance for LiMDFB cells.
Tris(4-fluorophenyl) Phosphine and Tris(2,2,2-trifluoroethyl) Phosphite as Flame-Retarding Additives in Li-Ion Batteries
Authors: Nam Nguyen Dang , Park In Jun , Kim Jung-Gu
Published: March 2011

Tris(4-fluorophenyl) phosphine (TFPP) and tris(2,2,2-trifluoroethyl) phosphite (TTFP) were used as flame-retarding additives in Li-ion battery electrolytes. The cell performance of the TFPP- and TTFP-containing electrolytes was examined by cyclic voltammetry, differential scanning calorimetry, electrochemical impedance spectroscopy and scanning electron microscopy. The flammability of the electrolytes was also examined by measuring the self-extinguishing time of the electrolytes. The results showed that the TTFP additive suppressed the flammability of the electrolyte, improved the thermal stability of the battery and its electrochemical cell performance. On the other hand, the TFPP additive only improved the thermal stability of the electrolyte at the expense of a slight decrease in electrochemical cell performance. The results show that TTFP is a better flame-retarding additive in the electrolyte of Li-ion batteries than TFPP.
Gamma Radiation-Induced Carbon Steel Corrosion
Authors: Daub Kevin , Zhang Xueyuan , Noël James J. , Wren J. C.
Published: March 2011

Carbon steel waste containers have been proposed in a number of national nuclear waste management programs. Although redox conditions in the sedimentary clay environments in which these containers would be placed will be anoxic, gamma irradiation would produce oxidizing conditions at the container surface. The effect of gamma radiation on carbon steel corrosion in de-aerated solutions was studied as a function of pH and temperature. The corrosion kinetics were studied by monitoring the corrosion potential (Ecorr) in-situ, and periodically performing linear polarization and electrochemical impedance spectroscopy measurements to determine polarization resistances. The surfaces, and cross sections of irradiated carbon steel coupon samples were also examined using SEM, XPS, and Raman spectroscopy. Preliminary results indicate that gamma irradiation increases the corrosion potential from a region where the anodic oxidation is limited to Fe(OH)2 and Fe3O4 to a region where the oxidation of Fe(OH)2 to gamma-FeOOH and Fe3O4 to gamma-Fe2O3 is possible.
Zinc Nickel Codeposition in Ammonium Sulfate Combined Effect of Cadmium and Boric Acid
Authors: Addi Yassine , Duverneuil Patrick , Khouider Ali
Published: March 2011

Zinc-nickel electrodeposited alloys are of great interest since these alloys show higher corrosion protection, better mechanical properties and thermal stability compared to bare zinc and other zinc alloys coatings. Zinc-nickel alloys were obtained from ammonium sulfate baths in the presence of boric acid and boric acid-cadmium. It has been shown that anomalous codeposition can be minimized by using both boric acid and cadmium. Boric acid decreases current density which minimizes anomalous deposition, in the other hand cadmium decreases strongly zinc deposition. The combination of boric acid and cadmium increases the percentage of nickel in the deposit. In a way the combination of boric acid and cadmium allows to obtain a ternary coating Zn-Ni-Cd which has higher nickel content compared to that in Zn-Ni obtained from ordinary Zn-Ni baths .
Electron Transfer at L-Cysteine Monolayer on Palladium Surface: A pH Effect Study
Authors: Feliciano-Ramos Ileana , Caban-Acevedo Miguel , Cabrera Carlos R.
Published: March 2011

The electrochemical properties of L-cysteine self assembled monolayer on palladium surface has been investigated. The effect of immobilization time of L-cysteine monolayer on palladium was studied by cyclic voltammetry (CV). Further, the electron transfer of the Fe(CN)63-/4- redox couple at different pH values was used to evaluate the protonation and deprotonation of the functional groups (NH2, COOH) at the modified electrode surface by using CV and electrochemical impedance spectroscopy (EIS). When the pH of the solution is high (ca. 11), the monolayer posses negative charge, Fe(CN)63-/4- current is inhibited. On the contrary, a different behavior at low pH (ca. 2) has been found. From the data obtained by CV and EIS, the surface pKa was found to be 7.3 and 7.1, respectively. At pH 7, we have compared Fe(CN)63-/4- peak currents as a function of scan rate, at different supporting electrolytes.
Engineered Nano-Scale Ceramic Supports for PEM Fuel Cells
Authors: Blackmore Karen J. , Bauer Eve , Elbaz Lior , Brosha Eric L. , McCleskey Thomas M. , Burrell Anthony K.
Published: March 2011

Alternative supports for polymer electrolyte membrane fuel cells were synthesized and catalytic activity was explored using electrochemical analysis. High surface area, molybdenum nitride supports were synthesized by rapidly heating a gel of polyethyleneimine bound molybdenum in a tube furnace under a forming gas atmosphere. Subsequent disposition of platinum through an incipient wetness approach lead to dispersed crystallites of platinum on the conductive support. The supports without platinum are highly stable to acidic aqueous conditions and show no signs of oxygen reduction reactivity (ORR). However, once the 20 wt% platinum is added to the material, ORR activity comparable to XC72 based materials is observed.
Degradation and Durability of SOFC Materials by the Impurities
Authors: Horita Teruhisa , Kishimoto Haruo , Yamaji Katsuhiko , Brito Manuel E. , Yokokawal Harumi
Published: March 2011

The effects of impurities on degradation of stacks were examined for 5 different kinds of stacks. The voltage degradations of stacks were improved from FY2008 and the voltage degradation was as low as 0.5% levels. Low concentration levels of impurities in the stack components were successfully measured by the SIMS technique. For impurity affected degradation, some degradation factors were considered associate with chemical reaction of impurities.
Micro-Tubular SOFC Systems - Fabrication, Testing and Analysis of Micro-Tubular SOFC
Authors: Yamaguchi Toshiaki , Suzuki Toshio , Sammes Nigel M.
Published: March 2011

This report summarizes the testing and analysis results on the electrochemical evaluation of a micro-tubular SOFC supported by a micro anode tube, composed of Sc2O3-doped ZrO2 (ScSZ) and NiO mixture. The cell was fabricated through a co-sintering of the ScSZ electrolyte and NiO-ScSZ anode support, and then a La0.6Sr0.4Co0.2Fe0.8O3-x-Ce0.9Gd0.1O1.95 cathode layer was deposited on the electrolyte film. Evaluation was conducted using a potentio/galvanostat and impedance analyzer under a humidified hydrogen flow. Power densities at 0.7 V were 29.4, 154.3 and 382.1 mW/cm2 at 500, 550 and 600 C, respectively. Impedance analyses showed that with increasing operation temperature, ohmic and electrode activation resistances (semicircle at higher frequency region) became decreased, while gas diffusion resistance (semicircle at lower frequency region) depended weakly upon the temperature above 550 C.
Quick-Start and Seal-Less Planar SOFC Module
Authors: Bossel Ulf
Published: March 2011

A compact SOFC module has been developed for portable, mobile and stationary applications and for hybrid operation with batteries. The bipolar plates of this SOFC generator are equipped with electric heating elements. During start-up, the stack can be brought to operating temperature of 600°C in three minutes. The power may be drawn from a battery which can be later recharged at times of low power demand. For stationary application, heating energy may be drawn from the grid. The module can also be rapidly brought to operating temperatures with heat generated externally by the combustion of fuel. To minimize this initial energy consumption, a number of innovative features have been integrated in design and operation of stack and system of this innovative SOFC solution. The stack is suspended inside a hermetically sealed can to minimize heat losses by conduction and to avoid gas leakage from the stack by pressure equilibration.
Improvement of Electrical Efficiency of Solid Oxide Fuel Cells by Anode Gas Recycle
Authors: Tanaka Yohei , Momma Akihiko , Sato Katsutoshi , Kato Tohru
Published: March 2011

Anode gas recycle (AGR) is one of the methods to enhance fuel utilization. In this paper, electrochemical performance of a single planar solid oxide fuel cell (SOFC) was investigated with/without AGR. Cell performance at AGR was successfully evaluated by our simulated-reformate generator without carrying out AGR actually. It was clarified that cell voltage more than 0.8 V could be obtained with AGR at utilization of 90% methane fuel and 45% air, 700ºC and 400 mA cm-2. The cell voltage was by 20 mV higher than one without AGR at the same utilizations. DC electrical efficiency more than 69%-LHV can be expected at AGR-SOFC which is by 2 percent points higher than one without AGR. Furthermore, it was found that deviation of cell voltage against change in current at a constant flow-rate and time constant for gas conversion in anode would be twice smaller with AGR than without AGR.
Advances in Development of Coal-Based Integrated Gasification Fuel Cell Systems Utilizing Solid Oxide Fuel Cell Technology
Authors: Ghezel-Ayagh Hossein , Way Richard , Huang Peng , Walzak Jim , Jolly Steven , Patel Dilip , Willman Carl , Davis Keith E. , Stauffer David , Vaysman Vladimir , Asapu Sunitha , Borglum Brian , Tang Eric , Pastula Michael , Petri Randy , Richards Mark
Published: March 2011

FuelCell Energy is developing solid oxide fuel cell (SOFC) systems and technology for very efficient, economically viable, coal-to-electricity power plants utilizing synthesis gas (syngas) from a coal gasifier. In addition to the 500 MW (nominal) size Baseline Power Plant system, a small-scale system (>250 kW) for Proof-of-Concept Module test is being developed. SOFC technology development includes cell performance enhancement, stack building block scale-up, stack tower design and validation tests. Development of a 250 kW module accommodating multiple stack towers is included. The Baseline Power Plant system is designed to remove at least 90% of carbon in the syngas, for sequestration as CO2. The Integrated Gasification Fuel Cell power plant is expected to achieve near-zero emissions to the environment. System optimization to achieve >55% electrical efficiency based on coal higher heating value has been carried out. The SOFC power block layout and factory cost estimate have been generated.
Electron Transport Modeling for a Portable PEMFC Stack Using Star-CD
Authors: Ippolito James , Shimpalee Sirivatch
Published: March 2011

Presented is an interesting and substantive paper in the development of effective CFD models. The paper presents a fully three-dimensional, computational fluid dynamics (CFD) study, using STAR-CD, to investigate the operating response of a PEMFC stack when catastrophic failure occurs. Typical failure modes that the CFD model can readily predict include flooding and dehydration. In this study, the failure is imposed superficially and the resulting electrochemical distributions are presented and analyzed. While, in this case, the failure was imposed, the CFD model can predict failure in cases such as poor water management.
A Comparison of Fuel Cell Test Protocols
Authors: Bloom Ira , Walker Lee , Basco John , Malkow Thomas , De Marco Giancarlo , Tsotridis Georgios
Published: March 2011

Argonne National Laboratory (Argonne) and JRC-IE are collaborating with the European Union's FCTESQA project to compare and validate the fuel cell test protocols being developed by the European Union and the United States. These protocols consist of how to obtain polarization curves and cycling profiles. The work at Argonne showed that when performed at one site, there were no significant differences in the shape and trend of the polarization curve. These findings were observed using two fuel cells stacks representing different technologies. In the polarization data there was a test-site-to-test-site difference, on the order of 5%. Thus far, the work with the cycling profiles showed that there are also differences in how the stack ages. The underlying reasons for these differences are under investigation.
Development of Hydrogen Fuel Cell Motorcycle in South East Asia
Authors: Weigl Joerg D. , Inayati Inayati , Saidi Hamdani
Published: March 2011

Motorcycles are the most popular vehicles for motorised individual transport in Asia. Millions of motorcycles cause the majority of traffic-based air pollution. A prototype of a clean, silent and fuel efficient hydrogen fuel cell powered Motorcycle demonstrates an alternative. With the prototype of Pios Fuel Cell Motorcycle a proof of concept is done. "Pios" Fuel Cell Motorcycle is the latest prototype of a series of hydrogen fuel cell powered vehicles. The power train of the fuel cell motorcycle consists of fuel cell system, in hybrid with lithium polymer-ion battery and ultra capacitor module. A direct-coupled permanent magnet AC motor and an overrunning clutch coupled brushless DC motor are implemented as traction motors. To analysis different drive train configurations extensive dynamometer lab test were done. A comparison of direct fuel cell drive train with various hybridisation drive trains with ultra capacitor and lithium battery were systematically tested and analysed.
A Prototype of the High Efficiency Three-Less (HETL) Fuel Cell System for Underwater Platforms
Authors: Yoshida Hiroshi , Hyakudome Tadahiro , Ishibashi Shojiro , Sawa Takao , Tani Toshihiro , Iwata Mitsuyoshi , Moriga Takuya
Published: March 2011

Since 2007 we have developed a new concept underwater fuel cell system for survey and ocean resource explorations in entire oceans. In 2009 the desktop system marked operating efficiency of over 60 % and long operation of 1000 hours. Last October we completed building the prototype of the fuel cell system to be installed on an underwater platform.
Tubular Solid Oxide Electrolysis Cells for Hydrogen Production
Authors: Kato Tohru , Honda Takeo , Negishi Akira , Sato Katsutoshi , Tanaka Yohei , Momma Akihiko , Kato K. , Iimura Y.
Published: March 2011

Tubular solid oxide electrolysis cells (SOECs) whose operating temperature is reduced to 700~800 oC are developed. To improve cell performance at the low temperature, Sc2O3 stabilized ZrO2 is chosen as electrolyte material and the thickness of the electrolyte layer is tried controlling about 10μm by slurry coating method. As a result of performance test, it is clarified that current density at thermoneutral point goes up to 0.46 Acm-2 at 750 oC. Furthermore, degradation phenomena in long term operation more than 1200 h are observed.
The U.S. Department of Energy Efforts in Fuel Cells for Portable Power Applications
Authors: Ho Donna , Kopasz John P. , Benjamin Thomas G. , Podolski Walt
Published: March 2011

U.S. DOE Efforts in Fuel Cells for Portable Power
Accelerated Electrochemical Oxidation of Small Organic Molecules in Hot Aqueous Base Solution
Authors: Jiang Junhua , Aulich Ted
Published: March 2011

To explore fundamentals that could direct more efficient use of small organic molecules in fuel cells, electrooxidation of methanol in aqueous alkaline media has been investigated as a model reaction in an intermediate-temperature range of 80° to 200°C using a pressurized electrochemical cell and by means of voltammetry and chronoamperometry. Well-developed cyclic voltammograms at varying temperature have been obtained using a Ag/AgCl internal reference electrode. It is encouragingly found that the electrooxidation of methanol in alkaline media on high-surface platinum electrode can be substantially accelerated by increasing temperature. The onset potential difference for the electrooxidation of hydrogen and methanol under similar conditions substantially decreases with increasing temperature, characterized by a value of around 50 mV at 150°C. High specific activity of Pt catalysts accessed from chronoamperograms further supports that the methanol electrooxidation is rather facile. These facts are important for the development of high-performance methanol fuel cells.
Ordered Arrays of Ti-Mn Oxide Nanotubes for High Capacity Li-Ion Battery
Authors: Raja Krishnan S. , Misra Mano
Published: March 2011

Ordered arrays of vertically oriented Ti-Mn oxide nanotubes were synthesized by a simple anodization method. XRD pattern showed presence of TiO2 in the form of anatase and rutile in addition to Mn2O3 after annealing at 500 ºC. An experimental battery with Ti-Mn oxide nanotubes as anode and LiCoO2 cathode was assembled and charge-discharge experiments were carried out at different rates. At 1 C discharge rate, the nominal capacity was about 474 mAh/g and remained constant even after 30 cycles. The discharge behavior showed two components; the first with a decreasing potential possibly owing to super capacitor like behavior of the nanotubes and the second component with a plateau potential at 1.9 V owing to Li-ion extraction from the nanotubular walls. Vertical orientation of the nanotubes, contact of the individual nanotubes with the substrate and Mn incorporation in the TiO2 ensured faster diffusion and better charge transportation than conventional TiO2 anode.
Characterization of Non-Aqueous Supercapacitors Based on Titanium Carbide Derived Carbon Electrodes and Novel Doubly Charged Cation Based Salts
Authors: Jänes Alar , Romann Tavo , Kurig Heisi , Lust Enn
Published: March 2011

The electrochemical characteristics for the supercapacitors based on the titanium carbide derived carbon (CDC-TiC) electrodes in 0.4 M N,N-dimethyl-1,4-diazabicyclo[2,2,2]octanediium tetrafluoroborate (DMDABCO(BF4)2), 0.2 M DMDABCO(BF4)2 + 0.2 M triethylmethylammonium tetrafluoroborate (TEMABF4), and 0.4 M TEMABF4 in g-butyrolactone (g-BL) have been studied using cyclic voltammetry, constant current charging/discharging and electrochemical impedance spectroscopy. The ideal supercapacitor behaviour was observed in a wide region of cell voltages (U < 3.0 V) in 0.4 M DMDABCO(BF4)2 in g-BL. The geometry of solvation shell around DMDABCO2+ has been optimized with molecular dynamics calculations and the coordination number equal to 15, have been proposed and compared with electrochemical and gas sorption data for CDC-TiC. The gravimetric capacitance 129 F g-1, energy 40.6 W h kg-1 and power 93 kW kg-1 were established for the CDC-TiC electrodes in 0.4 M DMDABCO(BF4)2 g-BL solution.
The Effect of Thermo-Vacuum Systems in the Dye Sensitized Solar Cell
Authors: Jehng Wern-Dare , Huang Yao-Min , Chen Chien Chon
Published: March 2011

Dye-Sensitized Solar Cell (DSSC) is currently under the developing progress in worldwide. Usually the laboratories adopt the method for absorbing dyes on film electrodes through placing the specimen sample in the dye for a lengthy soaking (12 hours). Consequently, the study employs the cooperation of thermo-vacuum system on the heating processes. We discovered from the experimental results that the best performance resulted from the heating process, which not only sped up the diffusion velocity of dye molecular being absorbed on the tube but also enhanced the photoelectric efficiency for solar cells, which thereby provided a substantial saving in time for dye soaking and greatly enhanced the economic benefits of products.
Electrochemical Behavior of Halogen-Doped Carbon Materials as Capacitor Electrodes
Authors: Tanaike Osamu , Yamada Yoshio , Yamada Katane , Kodama Masaya , Hatori Hiroaki , Miyajima Naoya
Published: March 2011

Modification of carbon material is one of the keys to improve the electrode of Electric double-layered capacitor. Some halogens are known to react with carbon strongly and intercalation compounds or residual ones are known to form with p-doping. In the present paper, bromine and iodine vapors are reacted with various carbon materials such as graphite, activated carbon and single-walled carbon nanotube and their electrochemical behaviors in the electrolyte of 1M (C2H5)4NBF4 / propylene carbonate were investigated. The pseudocapacitances of their halogen-predoped carbons due to the reaction of undope/redope of halogen from/into carbon electrodes were discussed from their cyclic voltammograms.
Electrochemical Effect of Cationic Gemini Surfactant and Halide Salts on Corrosion Inhibition of Low Carbon Steel in Acid Medium
Authors: Asefi Dourna , Arami Mokhtar , Mahmoodi Niyaz Mohammad
Published: March 2011

In this paper, the corrosion inhibition of cationic gemini surfactant 1,4-butan-bis- (dimethyl dodecyl ammonium bromide), in the absence and presence of halide salts (NaCl, NaBr and NaI) on steel in HCl was investigated at 20±1 °. The effects of pH, immersion time and salt concentration on the corrosion inhibition of steel were studied using weight loss, open circuit potential and electrochemical impedance spectroscopy. Inhibition efficiency increases by increasing surfactant concentration. Synergistic effect between surfactant and salts was studied. The inhibition efficiency increases by increasing salt concentration. This composite inhibitor containing gemini surfactant and halide was efficient and low-cost for steel corrosion inhibition in HCl.
Suppression of Lateral Encroachment of Ni Silicide into Si Nanowires Using Nitrogen Incorporation
Authors: Shigemori Naoto , Satou Sousi , Kakushima K. , Ahmet P. , Tsutsui K. , Nishiyama Akira , Sugii Nobuyuki , Natori Kenji , Hattori T. , Iwai H.
Published: March 2011

Si nanowire (NW) FET is one of the promising candidates for high-speed LSI devices in the future. In order to reduce the parasitic resistances of Si nanowires, the silicidation of the S/D regions is a very effective method. However, it has been reported that the full-silicidation leads to excessive Ni diffusion into Si NWs and this phenomenon may lead to some adverse issues such as uncontrollable channel length as well as short circuit between source and drain. On the other hand, there is a report that the diffusion of Ni could be suppressed by nitrogen incorporation into the Ni film prior to the silicidation.We applied this method for Ni full-silicidation of Si NWs and investigated the effectiveness on this structure. We also investigated the mechanism for the suppression.
Optical Properties for Antireflection Coating of TiAlN Thin Films for Semiconductor Photo Detectors
Authors: Razeghi Ali Mohammad , Hantehzadeh Mohammad Reza
Published: March 2011

Titanium aluminum nitride thin film by DC magnetron sputtering was deposited on Si substrate. The thickness variation of titanium aluminum nitride for different Nitrogen and Argon gas composition at different wavelength in the range of 200 to 2500 nm is investigated using reflection spectroscopy. The morphology of titanium aluminum nitride films is characterized using atomic force microscopy AFM. Experimental results show that increasing the nitrogen gas in the mixture makes the film thicker and less reflective.
Observation of Tunneling FET Operation in MOSFET with NiSi/Si Schottky Source/Channel Interface
Authors: Wu Yan , Shigemori Naoto , Sato Soushi , Kakushima K. , Ahmet P. , Tsutsui K. , Nishiyama Akira , Sugii Nobuyuki , Natori Kenji , Hattori T. , Iwai H.
Published: March 2011

Tunnel FET characteristics has been investigated for MOSFETs with NiSi/Si schottky source structure. Ni silicide were formed by the reaction of Ni with SOI silicon source layer, while ordinary diffusion P+ layer was formed for the drain electrode. On-and off-state currents have been evaluated with this structure. The tunnel FET operation is confirmed by the almost constant subthreshold swing at temperatures below 150K.
Redox Stability of Sm0.95Ce0.05Fe1-xCrxO3-δ Perovskite Materials
Authors: Bukhari Syed M. , Giorgi Javier
Published: March 2011

This manuscript is about the study of redox stability of Sm0.95Ce0.05Fe1-xCrxO3-δ (x=0-0.10) perovskite materials. These are stable under reducing atmosphere at temperature below 800oC and phase separation does happen at higher tmperatures.These materials have ability of oxygen recapturing when exposed to air after reduction treatment.The reduction treatment helped in improving electrical conductivity due to formation of nanoparticles on the surface. Indeed x=0.03 has highest electrical conductivities under both oxidizing and reducing condition.