bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Electrochemical Deposition of Metal-Organic Frameworks
Authors: Campagnol Nicolo` , Van Assche Tom , Stappers Linda , Denayer Joeri F. M. , Binnemans Koen , De Vos Dirk E. , Fransaer Jan
Published: October 2014

The electrochemical deposition of Metal-Organic Frameworks (MOFs) is an interesting technique to synthesize adherent, microporous layers on top of metal substrates. However, up to now not much is known about this process, and in this paper a four phase mechanism is proposed to better understand it. The study focuses on how the nucleation of these compounds starts and proceeds, what the influence of the solvent is, the stresses in the growing layers, and the origin of defects like delamination and crystal detachment.
Effect of Bias-Voltage in H2/N2 Plasma Treatment on Porous Low Dielectric Constant Materials
Authors: Cheng Yi-Lung , Huang Jun-Fu , Bo Tian-Cih , Lin Bing-Hong , Chen Chia-Ming
Published: October 2014

Porous low-dielectric constant (low-k) materials are needed for advanced technologies to improve signal propagation. Plasma treatments in interconnection fabrication have been considered to be critical steps to impact the low-k films’ properties. This study investigates the degradation of the porous low-k films by plasma exposure using several kinds of treatment conditions. Experimental results indicate that the increase in the dielectric constant and the degradation in the reliability for the plasma-treated low-k films were related to the decreased amount of Si-CH3 bonds and the absorbed amount of H2O or OH groups within the film. Plasma treatment with pure H2 gas extracts more CH3 groups from the porous low-k film and forms a larger amount of H2O or OH groups. Although the plasma-treated low-k films using N2 gas can suppress H2O or OH group formation, the increase in the dielectric constant is higher due to the formation of Si-N or C-N bonds. Plasma treatment using a mixture of H2/N2 gas can obtain a balance result in the dielectric constant increase and absorbed moisture uptake. Furthermore, increasing bias-voltage on the sample electrode during H2/N2 Plasma treatment can effectively suppress the degradation of the porous low-k dielectrics.
Enhanced Catalytic Activity of Platinum Nanowires on Carbon toward the Oxygen Reduction Reaction
Authors: Wainright Robert John , Umasankar Yogeswaran , Ramasamy Ramaraja P
Published: October 2014

The catalysis of the oxygen reduction reaction (ORR) was studied for heteronanostructures consisting of platinum and platinum alloy nanowires supported on carbon nanospheres for applications in proton exchange membrane fuel cells (PEMFCs). The Pt nanowires on carbon nanospheres (PtNWs-C) were grown by slow chemical reduction. This was followed by the introduction of a second metal (Co) in the ratio 3:1 Pt to Co by a moderate chemical reduction and subsequent annealing to allow the diffusion of cobalt into the Pt-NWs to make PtCoNWs-C. The incorporation of the second metal and annealing process slightly increased the overpotential for the PtCoNWs-C relative to the PtNWs-C, yet the bi-metallic structures exhibited increased kinetic currents and lower Tafel slopes compared to the PtNWs-C and standard XC-72 Pt-C catalysts. Rotating disk electrode (RDE) studies revealed that the PtCoNWs-C performed in a superior manner to the standard XC-72 Pt-C catalysts.
Surface Fermi Energy and Activity of Atomically Layered Pt/Ru Catalyst
Authors: Takmeel Qanit , Moghaddam Saeed
Published: October 2014

Understanding the relation between the surface composition of a catalyst and its catalytic activity toward species is key to enhancing the science of catalysis. The current state of knowledge on platinum-ruthenium (Pt-Ru) activity toward methanol is that an alloy with a 1:1 ratio of the two metals exhibits the highest activity. Here, we correlate the activity of a bilayer Pt-Ru catalyst to its surface composition. By using electrochemical techniques such as Cyclic Voltammetry (CV) and Copper Underpotential Deposition (Cu-UPD) in conjunction with Kelvin Probe Force Microscopy (KPFM), we demonstrate the effect of surface Fermi energy on catalyst activity.
Distributed PEFC Performance during Cationic Contamination
Authors: Uddin Md. Aman , Wang Xiaofeng , Ozdemir M. Ozan , Qi Jing , Bonville Leonard J. , Pasaogullari Ugur , Molter Trent
Published: October 2014

PEFC performance during cationic contamination was studied by in-situ injection of 21.2 ppm level of Ca2+ in the air stream of a segmented cell. As expected, performance varied from the cell inlet to the outlet. During the contaminant injection, segments on the upstream end of the cell were affected first by the contaminant resulting in decreased current. At the same time, current for the other segments increased despite the presence of contaminants in order to maintain constant total current. Due to contamination, cell voltage decreased and fluctuated mainly due to mass transport losses. During this testing, the contaminant was found to precipitate on both the cathode flow field and the surface of the GDL. As the test progressed, the contaminant penetrated into the GDL and deposited, causing mass transport losses. No contaminant was detected inside the CCM. It is seen that the GDL acted as a barrier to the transport of cationic contaminant to the CCM.
Development of a High Resolution Thermal Model of the Microporous Layer found in PEM Fuel Cells
Authors: Botelho Steven Joseph , Bazylak Aimy
Published: October 2014

In this study, the nanoscale features of the polymer electrolyte membrane (PEM) fuel cell microporous layer (MPL) are considered in the determination of the effective thermal conductivity. A combination of scanning electron microscopy and atomic force microscopy was used to visualize SGL-10BB and SGL-10BC MPLs, and we found that the MPL typically consists of randomly positioned spherical particles with diameters ranging from 10-100 nm. We developed a unit-cell model packed with spherical particles of various diameters to represent the MPL based on our high resolution visualizations. A thermal analysis based on the Gauss-Seidel iterative method for conductive heat transfer was utilized to obtain the effective thermal conductivity of various unit-cell configurations. It was found that the nature of contact between MPL particles dominates the effective thermal conductivity, which provides valuable insight for future MPL designs. To the authors’ best knowledge, this is the first investigation of how the nanoscale features (namely particle to particle contacts) affect the bulk effective thermal conductivity of the material. This nanostructed model can also be used for future investigations, such as oxygen diffusion and electrical conductivity studies.
Stability of Pt-Ru Alloy for Anode Catalyst in PEFC Fuel Cell: A Density Functional Theory Study
Authors: Alam Md. Khorshed , Takaba HIromitsu
Published: October 2014

It is well known that Pt-Ru alloy exhibits a promising catalytic activity for fuel cells. In this work we present density functional theory (DFT) study of the randomly mixed Pt-Ru alloys and discussed its stability based on the relative position of Pt and Ru atoms. The structures are modelled as five layer slabs because the ratio of surface atoms comparable with that for clusters about 3 nm sizes. The top surface fully covered by the Pt atom exhibits highest stability compared with other randomly mixed Pt-Ru alloys. We also discuss here the probability of Pt-Ru bond ratio (MPt-Ru/MPt-Ru+MPt-Pt) in the Pt-Ru alloy decreases with increasing the surface atom ratio (surface atom/Total number of atom), which is compared with available X-ray absorption fine structure data.
Concentrated Solution Model of Transport in All Vanadium Redox Flow Battery Membrane Separator
Authors: Ashraf Gandomi Yasser , Zawodzinski Thomas A. , Mench Matthew M.
Published: October 2014

A model of transport across the ion-exchange membrane in all-vanadium redox flow batteries has been proposed based on concentrated solution theory for species with high concentration. The model is based upon the Stefan-Maxwell multicomponent diffusion equation where the fluxes of the species including protons, bisulfate, water and the sulfonate functional groups are fully coupled. The driving force for species transport has been modeled in terms of concentration and electrostatic potential gradients. The ionic transference numbers as well as water electro-osmosis drag coefficient has been calculated for different acid concentrations.
Dynamics of Deposited Li2O2 on Cathode Surface in Li-O2 Battery by First-Principles Molecular Dynamics
Authors: Yamamoto Wataru , Alam Md. Khorshed , Takaba Hiromitsu
Published: October 2014

The lithium-O2 systems capture worldwide attention as a possible battery for electric vehicle propulsion. However, there are numerous scientific and technical challenges that must be overcome if this alluring promise is to turn into reality. In this study, using first principles molecular dynamics (FPMD), we first time report the dynamical behavior of discharge deposit product such as Li2O2 and investigate the deposit film thickness effect on the electrical conductivity of the cathode surface. We show that how discharge products accumulate on the cathode surface with time and deposit on catalysts surface as well as influence of the species transportation process in Li-O2 battery.
On the Structure-Function Relationship of Cobalt and Manganese Oxides as Oxygen Evolving Catalysts for Light-Driven Water Electrolysis: An In-Line Synchrotron Radiation Photoelectron Spectroscopy Study
Authors: Hillebrand Philipp , Ramirez-Caro Alejandra , Calvet Wolfram , Bogdanoff Peter , Fiechter Sebastian
Published: October 2014

In the effort to develop an efficient and cost effective photoelectrochemical device for water splitting driven by sunlight only, transition metal oxides are promising candidates to catalyze the oxygen evolution reaction (OER) at the anode. We used X-ray photoelectron spectroscopy (XPS) to characterize very active manganese and cobalt oxide thin films deposited on FTO substrates before and after the application of different anodic potentials, in order to investigate the bias potential dependent changes on the catalysts’ surfaces. α-Mn2O3 undergoes a reversible partial oxidation from Mn3+ to Mn4+ under high anodic potentials, while the transition from Co2+ to Co3+ in amorphous CoOx samples occurs already at a potential well below the OER onset potential. This Co3+ state is then stable throughout the investigated potential range and no clear evidence for a Co4+ state at or above the OER onset potential could be found. We conclude that the OER reaction mechanism on the surface of these oxide films might be significantly different.
Chitosan and Ionic Liquid Based Solid Polymer Electrolytes: The Anion Alkyl Chain Length Effect
Authors: Leones R. , Sentanin Franciani , Esperança J.M. S.S. , Pawlicka Agnieszka , de Zea Bermudez V. , Silva M. M.
Published: October 2014

This work describes novel polymer electrolytes based on chitosan matrix doped with three ionic liquids of the series 1-ethyl-3-methylimidazolium alkylsulfonate [C2mim][CnSO3]. The effect of the increase of the anion alkyl chain length on the thermal, morphological and electrochemical properties of these materials was studied. The samples were characterized by means of thermal analysis (DSC and TGA), atomic force microscopy (AFM), complex impedance spectroscopy and cyclic voltammetry. All electrolyte samples exhibited an amorphous nature and thermal stability up to 150 ºC. These materials have adequate electrochemical stability and their ionic conductivity decreases with the increase of the anion alkyl chain length.
Traceability of pH Measurements
Authors: Camoes Maria Filomena , Spitzer Petra
Published: October 2014

The free acidity of an aqueous solution is expressed in terms of its pH, a measure of the hydrogen ions activity. Being the most often measured chemical parameter, pH is used in the assessment of other chemical species and in comparative exercises. The validity of conclusions requires that the values of pH measurements are traceable to common references and ultimately to the SI. Measurements are recommended in pH meters submitted to prior calibration with reference pH buffers whose pH values have been established against conventionally assigned pH values of primary pH buffer standards of low ionic strength, I≤ 0.1 mol kg-1. This chain of operations is supported on the quality associated with, namely, buffers, electrodes, procedures, calculations and model assumptions. An overview is given of recent fundamental and applied studies addressing these various issues, for the particular case of highly saline waters approaching the complex composition of seawater.
Modeling and Simulation of Electrochemical Impedance Spectra in Lithium-Air Batteries
Authors: Mehta Mohit , Andrei Petru
Published: October 2014

In this article we compare the impedance spectra of Li-air batteries using two models: one based on the analytical solution of the oxygen diffusion equation in the cathode and the other one based on finite element simulations. The first model was recently introduced by us to compute the impedance of lithium-air batteries with organic electrolyte and, here, is presented in slightly different form. The second model is based on the solution of the transport equations in concentrated solutions; the complex impedance is computed by the linearizing the partial differential equations that describe the mass and charge transport in Li-air batteries and includes the effects of the oxygen and lithium diffusion, finite electrolyte conductivities of the electrolyte and electrons, and Butler-Volmer kinetics at the anode and cathode.
Nickel Oxide Carbon Nanofiber Composite for Electrochemical Oxidation of Methanol
Authors: Al-Enizi Abdullah M , El-Zatahry Ahmed A , Abdullah Aboubakr Moustafa , Al-Deyab Salem S
Published: October 2014

Electrospun fibers of a mixture of polyvinylpyrrolidone (PVP), polyaniline (PANI) and graphene were stabilized for 2 h at 200 °C and then carbonized at 800 °C for 5 h. Composites were prepared by depositing Ni(OH)2 on the carbon nanofibers (CNFs) and calcining them at different temperatures. The composites were characterized using XRD, TEM and SEM. The effect of the calcination temperatures on the electrochemical catalytic properties towards methanol (MeOH) oxidation was studied using cyclic voltammetry and electrochemical impedance spectroscopy. The analysis of the chronoamperometry measurements confirmed a significant increase in the real surface area for the CNF/NiO composite as the calcination temperature increases. The real surface area is increased at calcination temperatures of 400 and 500 oC more than 20 times higher than that calcined at 300 oC. The oxidation of MeOH was not found to be a purely diffusion controlled process. The CNF/NiO composite has shown, not only, a good stability as the potential was cycled between a large potential window, but also, the electrocatalytic properties was enhanced which was attributed to the surface activation during the cyclic process. The impedance parameters were calculated from the EIS measurements proved that this system has two time constants: one for the adsorption and the other for the charge transfer.
Chemically Impregnated Abrasives Provide High Planarization Efficiency Copper CMP Slurry
Authors: Ihnfeldt Robin
Published: October 2014

As device sizes decrease, next generation CMP slurries must achieve planarization on increasingly higher aspect ratio structures. Current copper CMP slurries have a limited planarization efficiency (PE) (ratio of step height removed to thickness removed). Without an improvement in PE, CMP is going to become an increasingly expensive and limiting step in the semiconductor manufacturing process. This research is focused on developing a copper CMP slurry containing nano-sized contact release capsules (nano-CRC). Nano-CRC based slurries consist of a core-shell nanoparticle where the mechanical and chemical components are combined into a single entity. Nano-CRC particles made from porous colloidal silica abrasives were impregnated with glycine, and then coated with a polymer to encapsulate the glycine. Initial results have yielded simultaneously high PE and high material removal rate, which will improve planarity and decrease processing costs.
Improving Selectivity on Germanium CMP Applications
Authors: Karagoz Ayse , Basim G. Bahar
Published: October 2014

In the presented paper, the adsorption characteristics of cationic and anionic surfactants on germanium and silica were studied in order to improve selectivity in germanium based shallow trench isolation chemical mechanical planarization applications. It was observed that the very strong or loose self-assembled surfactant structures can help obtain selectivity on the silica/germanium systems. Simultaneously, good defectivity control with a sufficient material removal rate was obtained. The surface charges manipulated by the surfactant adsorption and the hydrophobic nature of the germanium surface were main criteria on the selection of the proper surfactant/oxidizer system. In addition, impact of surfactant addition on particle-particle interactions controlling slurry stability was also investigated in the paper.
Synchotron Enabled Ex-Situ and in-Situ Mechanistic Interrogation of Energy Storage Systems
Authors: Brady Alexander , Kirshenbaum Kevin , Takeuchi Kenneth J , Marschilok Amy C , Takeuchi Esther S
Published: October 2014

A complete picture of the electrochemical processes and reaction fronts within batteries is difficult to form due to the complexities of the reactions and the difficulties of analytical interrogation of those reactions. Ex-situ measurements at various stages of reaction can provide mechanistic insight. However, configurational information is lost in the process. In-situ methods are typically hindered by the cell housing. In these studies we have used the high power NSLS synchrotron to perform in-situ EDXRD. By combining diffraction data with ex-situ methods we are able to create a more complete picture of the ongoing reactions within the cell.
Effect of Temperature on Characteristic of Carbon Nanotube Nano-Composite Electrode Supercapacitor
Authors: Huang Naibao , Kirk Donald W , Thorpe Steven J. , Liang Chenghao , Xu Lishuang , Zhang Shuchun , Li Wan , Sun Min
Published: October 2014

In order to evaluate the effect of temperature on the performance of supercapacitor using coconut shell activated carbon (AC)/carbon nanotubes (CNTs) as nano-composite electrodes, the supercapacitor’s properties were tested in 4mol L-1 KOH solution at 35℃~60℃.The results indicated, when temperature increased from 35℃ to 60℃, the resistance decreased from 0.83Ω to 0.78Ω by 6% and the capacitance increased from 93.32F g-1 to 104.36F g-1 by 11.8%. It was the contribution of high conductivity and the end open ration of CNTs. These results indicated that CNTs-based nano-composite electrode had good performance at high moderate temperature, and would be a promising material for use in low-cost electrical energy storage device.
Synthetic Strategies Impacting Voltage, Capacity, and Current Capability of Energy Storage Materials
Authors: Huie Matthew , Takeuchi Esther S , Marschilok Amy C , Takeuchi Kenneth J
Published: October 2014

Low temperature synthetic strategies for direct control of crystallite size and composition of energy storage materials will be discussed. This ability to synthetically control material properties enabled the systematic exploration of the fundamental properties of the materials, which reveals a dependence of electrochemical reversibility, current capability, and delivered capacity on chemical or physical properties, likely crystallite size. In a more general sense, fundamental studies involving the impact of physical and chemical properties of materials on their electrochemical properties are critical in the rational development of materials, which may address the present and future requirements for stationary and portable power.
Improvements in Li Air Batteries through Electrocatalysts, Electrode Structure Design and Modelling
Authors: Scott Keith , Sahapatsombut Ukrit , Cheng Hua
Published: October 2014

The performance of lithium oxygen batteries using a range of electrocatalysts is described. Alternative supports to carbons are considered including nickel foam, silver and titanium carbide. Titanium carbide gave exceptional discharge capacity of above 5000 mAh g catalyst
-1 which was twice that achieved with the best performing manganese dioxide catalyst. A Li metal air battery developed has produced cycling performance of 200 cycles with only a 50% reduction in capacity, in which it was operated for 3 months continuously. A macro-homogeneous model has been developed to evaluate the operating performance of a rechargeable non-aqueous Li-air battery
Nanoporous Anodic Bismuth Oxide for Electrochemical Energy Storage
Authors: Chitrada Kalyan C , Raja Krishnan S.
Published: October 2014

Thin films of nanoporous bismuth oxide were synthesized by a simple electrochemical anodization of bismuth substrate. Annealing the anodic nanoporous Bi2O3 at 240 °C for 2 h resulted in stabilization of the β-Bi2O3 phase that has an n-type conductivity. Longer annealing times resulted in partial formation of the more stable α-Bi2O3 phase that showed monoclinic lattice structure and p-type semiconductivity. Samples containing predominantly the β-Bi2O3 phase showed higher capacitance (1064 mF/cm2) than the samples containing a mixture of α-Bi2O3 + β-Bi2O3 phases (787 mF/cm2) at a current density of 10 mA/cm2. The higher capacitance of the samples annealed at 240 ⁰C for 2 h could also be attributed to higher charge carrier density than that of 6 h annealed sample.
Versatile Ternary Manganese-Nickel-Cobalt Compounds in Multi-Shell Spherical Structures as Electrode Materials for High-Capacity Lithium-Ion Batteries
Authors: Zhao Jianqing , Wang Ying
Published: October 2014

A full lithium-ion battery has been assembled based on nanoarchitectured ternary manganese-nickel-cobalt compounds, in which multi-shell spherical Mn0.54Ni0.13Co0.13(CO3)0.8 serves as anode and the subsequently lithiated Li-excess Li[Li0.2Mn0.54Ni0.13Co0.13]O2 with a yolk-shell structure acts as cathode. Multi-shell carbonate anode tested in a half cell with metallic lithium as the counter electrode reveals an unexpectedly high initial charge capacity of 1173.1 mAh/g at 25 mA/g. Accordingly, yolk-shell-structured Li-excess layered cathode material has been obtained through lithiation of carbonate compound, showing an initial discharge capacity of 250.7 mAh/g when cycled at 0.1 C (1C = 250 mA/g) in a half cell. Combination of nanostructured ternary transition metal carbonate anode and Li-excess layered cathode into a full lithium-ion battery results in a remarkable specific capacity above 250 mAh/g at 0.1 C in a voltage range of 0.1 - 4.0 V, which demonstrates as a very promising electrochemical device for future energy conversion and storage.
Modified Metal Oxide Nanostructure Deposited Semiconductor Interfaces: Tuning the Lewis Acidity of Reversibly Interacting Sites
Authors: Baker Caitlin , Laminack William , Gole James L.
Published: October 2014

We study the reversible response matrices formed at room temperature as metal oxide nanostructure decorated interfaces are modified through in-situ nitridation. Nanostructured TiO2, SnOx, NiO, and CuxO (x = 1,2), in order of decreasing Lewis acidity, are deposited to an n-type nanopore coated microporous porous silicon interface to direct a dominant electron transduction process for reversible chemical sensing in the absence of significant chemical bond formation. The in-situ modification of the metal oxides deposited to the interface changes the reversible interaction with the analytes NH3 and NO. The changes of the responses to the analyte are predictable within the framework of the Inverse Hard/Soft Acid/Base model. The trends are characterized by XPS measurements of the shift in the binding energy from that of the oxides and by infrared spectroscopy. Thus, nitridation significantly changes the response matrix for a given gas and creates a distinct new family of response matrices.
Co-Doped ZnO Nanomaterials as a Novel Platform for Hydrogen Peroxide Biosensing
Authors: Zhang Wen , Chang Yingxing
Published: October 2014

Co-doped ZnO nanofilms have been synthesized successfully on indium tin oxide glass by direct electrochemical deposition. They have been using as platforms to immobilize horseradish peroxidase enzyme and to enhance the response of hydrogen peroxide. The structure and morphology of Co-doped ZnO film have been characterized and the electrochemical testaments have been preformed to evaluate the sensing abilities. It was found that the Co-doped ZnO nanofilms had good conductivity and fast electron transfer in electrocatalytic reduction. According to the amperometry response, a broad linear response was in the range of 0.05 to 1.15 mM and the detection limit was 13 μM (S/N=3) within 10 s at an applied working potential of -0.3 V. The sensitivity and value for the electrode were 22.7 μA/mM and 2.93 mM, respectively. The proposed biosensor was not affected by other pollutants and maintained nearly 90% of its original activity after a monthly storage.
Corrosion Protection Studies of Crude Glycerol-Based Waterborne Polyurethane Coatings on Steel Substrates
Authors: Lee Yueh-Lien , Luo Xiaolan , Hu Shengjun , Li Yebo , Buchheit R.
Published: October 2014

Crude glycerol (CG), a low-value byproduct from the biodiesel industry, has a significantly different composition compared to pure glycerol. Generally, crude glycerol contains various impurities, such as methanol, water, soap, free fatty acids (FFAs), fatty acid methyl esters (FAMEs), and glycerides. In this study, crude glycerol-based waterborne polyurethane (WPU) coatings were prepared from polyols synthesized using crude glycerol as a sole feedstock via a thermochemical conversion process. The corrosion properties of coatings were characterized by electrochemical impedance spectroscopy (EIS), polarization measurement and salt spray test. The initial experimental results show that crude glycerol-based WPU coatings have a considerably enhanced corrosion resistant performance of metallic substrate.
Corrosion Inhibition of C-Steel Using Supported and Non-Supported Cu-Nanoparticles/Benzotriazole
Authors: Abdullah Aboubakr Moustafa , Atta Nada Farouk , Galal Ahmed , Afifi Asmaa Ahmed , Younan Nathalie A. , Mohamed Adel M. A.
Published: October 2014

Depositing Cu nanoparticles on the C-steel surface using the self-replacement technique has shown corrosion inhibition efficiency higher than 91% in acidic medium if the Fe/Cu system was preimmersed in 1 mM benzotriazole for 15 minutes. The use of polyaniline nanotubes as a support for the Cu nanoparticles did not enhance the inhibition efficiency of Cu nanoparticles for Fe. On the contrary, it decreased a little bit. This work compares between corrosion inhibition efficiency of the polyaniline nanotubes and Cu nanoparticles separately and in presence and absence of benzotriazole. In addition, this work introduces a new and simple technique that is able to decide how the benzotriazole molecules interact with the Cu surface. It was proven using this technique that at the free corrosion potential, the interaction takes place mainly through the adsorption mechanism rather than the Cu(I)BTA film formation one.
Microcapillary Polarization of Friction Stir Welds in AZ31B Magnesium Alloy
Authors: Savguira Yuri , North Thomas H. , Thorpe Steven J.
Published: October 2014

Corrosion of friction stir welds made in AZ31B magnesium alloy has been investigated using the microcapillary polarization technique. Various weld regions were examined in both spot and seam welds. The stir zone showed a higher reduction potential than the thermo-mechanically affected zone (TMAZ) and the base metal, due to the dissolution of β-Mg17Al12 particles. The absence of second phase particles resulted in elimination of harmful microgalvanic cells between the β-Mg17Al12 particles and the α-Mg matrix, and an increased concentration of aluminum in solid solution. The noble stir zone formed a macro galvanic cell with the base metal, which resulted in accelerated corrosion of the TMAZ. No significant variation in the electrochemical response of various weld zones was seen between seam and spot welds.
Corrosion Behavior of Carbon Steel in Piperazine Solutions for Post-Combustion CO2 Capture
Authors: Zheng Liangfu , Landon James , Matin Naser , Li Zhiao , Qi Guojie , Liu Kunlei
Published: October 2014

The corrosion behavior of A106 carbon steel in 30 wt.% piperazine (PZ, a cycling amine) solutions was investigated by potentiodynamic polarization, EIS, LPR, SEM/EDS, and XRD. For comparison, the corrosion was also conducted in the benchmark solvent of monoethanolamine (MEA) solution. Similar to MEA, initial corrosion testing results in PZ solvent showed that the corrosion rate increases with increases either in CO2 loading from 0.23 to 0.43 mol CO2/mol alkalinity (C/N) or in temperature from 20 to 80 oC. Short term corrosion investigations showed an approximately two orders of magnitude lower corrosion rate for A106 in 0.43 C/N CO2 loaded 30 wt.% PZ at 80 oC than in the same conditions but with 30 wt.% MEA. The difference was due to the ability to form a dense and protective FeCO3 layer on the metal surface in PZ as opposed to in MEA solutions. Possible mechanisms are discussed.
Effects of Hydrogen Sulfide on the Corrosion Behavior of High Strength Steel in Alkaline Solutions
Authors: Feng Ruishu , Beck Justin , Lvov Serguei N. , Ziomek-Moroz Margaret
Published: October 2014

In-situ electrochemical corrosion measurements were performed for high-strength low-alloy steels in 5 %wt. NaCl solutions of pH 7.5, 10.6, and 12.3 at 85 °C. It was observed that the corrosion typically reached a steady state by 60 hours. The corrosion rate at steady state was slower at higher pH, regardless of H2S concentration. The addition of H2S accelerated the corrosion rates of UD-165 at pH 7.5 and 12.3, but decreased the corrosion rate at pH 10.6. This could have been related to the autocatalytic effect of H2S and the nature of the corrosion product film on the surface. Both the Pourbaix diagrams and the surface analyses suggested that the corrosion products shifted from iron sulfides to iron oxides as the solution pH was increased.
Nanoporous Anodic Bismuth Oxide Photo-Anodes
Authors: Chitrada Kalyan C , Raja Krishnan S.
Published: October 2014

Bismuth oxide has widely been investigated for photo degradation of dyes for safeguarding the environment. However, not much work has been reported on bismuth oxide as a photo electrode material for solar water splitting. Bismuth oxide has well-dispersed valence bands that show enhanced mobility of charge carriers, high refractive index, and large dielectric constant. These properties are attractive for photo catalysis. Thin films of nanoporous bismuth oxide were synthesized by a simple electrochemical anodization of bismuth substrate. Annealing the anodic nanoporous Bi2O3 at 200 °C for 2 h resulted in stabilization of the metastable β-Bi2O3 phase at room temperature. A maximum photo current density of 0.97 mA/cm2 was observed for 10 V 30 min sample at an applied potential of 0.5 VAg/AgCl.
A Novel Process for Solar Hydrogen Production Based on Water Electrolysis in Alkali Molten Carbonates
Authors: Frangini Stefano , Felici Claudio , Tarquini Pietro
Published: October 2014

In order to evaluate the technical feasibility of a novel solar hydrogen production process, the molten carbonate electro-reduction behavior of water in the range 505-600°C was examined in this paper. Reaction kinetics and mechanism of the water reduction process was elucidated by using galvanostatic polarization methods and cyclic voltammetry. Two different water electrolysis mechanisms were found to be active in this temperature range, involving either bicarbonate or hydroxide anions as intermediate species, much depending on reaction conditions and melt temperature. Due to lack of knowledge, the bicarbonate mechanism was studied in detail. In accordance with a rapid thermodynamic decrease of bicarbonate stability above the 500°C, the voltammetric data showed a transition from bicarbonate to hydroxide mechanism at around 550°C. The results also indicated that water electrolysis in alkali molten carbonates can be conveniently operated in the 500°C area, where the relatively higher bicarbonate stability may enable a more rapid reaction than at higher temperatures.
Thermal Activiation of Sr3Fe2O7 Electrocatalysts for Water Oxidation at Neutral pH
Authors: Takashima Toshihiro , Ishikawa Koki , Irie Hiroshi
Published: October 2014

The Ruddlesden-Popper-type layered perovskite strontium ferrite (Sr3Fe2O7) was studied as an electrocatalyst for water oxidation to molecular oxygen (O2). The electrocatalytic activity of Sr3Fe2O7 was found to be dependent on the temperature, and the overpotential for water oxidation was markedly lower at 70 oC than at 30 oC. Namely, at pH 7, O2 evolution initiated with overpotentials of approximately 100 and 300 mV at 70 and 30 oC, respectively. When lanthanum-substituted Sr3Fe2O7, Sr2.6La0.4Fe2O7, was used to catalyze O2 evolution, the distinctive temperature dependence disappeared and O2 evolution was driven with a low overpotential even at 30 oC. These results suggest that the formation of Fe4+ is important for decreasing the overpotential for water oxidation to produce O2.
Degradation Behavior of PTB7:PC71BM and P3HT:PC71BM Organic Solar Cells with a TiOx Interlayer
Authors: Abdel-Fattah Tarek M , Younes Enas m , Namkoong Gon , El-Maghraby E M , Elsayed Adly , Abo Elazm A. H.
Published: October 2014

In this study, the stability of organic photovoltaic with bulk heterojunction (BHJ), thieno(3,4-b)-thiophene/benzodithiophene copolymer and (6,6)-phenyl C71 butyric acid methyl ester (PTB7:PC71BM) treated with titanium oxide (TiOx) interlayer was compared with that of organic solar cell based on poly (3-hexylthiophene) and [6,6]-phenylC71butyric acid methyl ester (P3HT/PC71BM) with TiOx interlayer. TiOx was prepared by sol-gel method. The crystalline structure of TiOx was investigated by X-ray diffraction (XRD) while the absorption spectra, and surface morphology of the BHJ were studied by UV-Vis spectroscopy and atomic force microscopy (AFM) respectively. The electrical properties of the resultant devices were generated by measuring the current density–voltage (J–V). Also the normalized efficiency of both devices as a function of time has been measured and stability was analyzed in terms of optical, structural and morphological degradation.
Nanocomposite Dye Sensitized Solar Cell (DSSC) Based on Titanium Oxide/Tungsten Oxide Photoelectrode
Authors: Feteha M. Y. , Ebrahim Shaker , Soliman Moataz , Saad Laila , Abdel-Fattah Tarek M
Published: October 2014

In this work, a novel dye sensitized solar cell (DSSC) structure -ITO/(TiO2/WO3)/N3dye/electrolyte/graphite/PANI/SWCNTs/ITO- was fabricated with different ratios of WO3 nanoparticles. It was observed that the depositing of a layer of WO3 nanoparticles- 3% wt. ratio- on TiO2 photoelectrode, enhances the DSSC efficiency from 0.28 % to 1.2%. This is due to reduction in charge injection resistance at the electrolyte/photoelectrode interface.
Measurement of Oxygen Gas Transport Resistance in Cathode Catalyst Layers of PEFC
Authors: Yasuda Hiroshi , Kobayashi Kenji , Daimaru Akimasa , Hori Michio
Published: October 2014

Some in-situ techniques measuring limiting current in order to analyze the reactant gas transport structure in the cathode of PEFC have been proposed. By these methods, it has been found that the reactant gas transport resistance in cathode catalyst layers (CLs) (RCL
) was separated into two components, diffusion resistance of catalyst pore (Rpore
) and diffusion resistance around Pt surface (RPt
). This paper describes a method to determine Rpore

and RPt
by means of only measuring limiting currents, without any additional measurements. RPt
and Rpore
with different catalyst types and various ionomer carbon ratios (I/C) were measured and it was found that these parameters depend on I/C.
Studies of Metal Electrodeposition in Adiponitrile
Authors: Cheek Graham T.
Published: October 2014

The solvent system adiponitrile (ADN) / tetraethylammonium tetrafluoroborate (TEA BF4) has been used to study the electrodeposition of various metals at both platinum and glassy carbon electrodes. Well-defined stripping peaks were found at each electrode for AgNO3 and Cu(NO3)2 systems, with slower electrodeposition kinetics at glassy carbon. For Hf(TfO)4 and Al(TfO)3, there is noticeable anodic activity after the initial reduction process; however, the stripping process is not as definite as in the silver and copper cases. Nucleation plots have been used to determine that copper(II) reduction at glassy carbon involves progressive nucleation at the peak reduction potential, while at platinum an instantaneous pathway is followed.
The Effect of Repeated Activation on Screen-Printed Carbon Electrode Cards
Authors: Martin Candace , Grgicak Catherine
Published: October 2014

Screen-printed carbon electrode cards have been recognized as an inexpensive and disposable sensing option with wide application. Despite their disposability, laboratories with high sample throughput may desire repeated use from each card. This study examined the ability of a commercial brand of cards to be reused using cyclic voltammetry (CV) and the reversible redox couple, hexaammine ruthenium. Activation, which improves electrode performance, was shown to affect the shape of the CV curves, the transfer coefficient, and the real electro-active surface area. Repeated activation has a compounding effect on these parameters, which provide insight to the condition and kinetics of the electrode surface. It was determined that screen-printed carbon electrode cards should not be reused with protocols that require electrochemical activation of the working electrode.
Optical Studies of Reactively Co-Sputtered BCN Thin Films
Authors: Prakash Adithya , Sundaram Kalpathy B
Published: October 2014

Boron carbon nitride (BCN) ternary compounds have similarities in the structure and difference in properties between graphite and hexagonal boron nitride (h-BN). Both theoretical calculations and experimental studies show that BCN compounds exhibit excellent mechanical, optical and electrical properties. The possibility to control the band gap (EG) by atomic composition and structure makes them good candidates for the application in electronic and photonic devices . In this work we deposited BCN thin films on quartz substrates by B4C and BN targets using RF and DC powers respectively at different N2/Ar gas flow ratios. Input power for B4C and BN are varied to achieve different composition of the BCN thin films to control the optical properties. The optical properties like transmission and reflectance are studied using the UV-visible spectrophotometer. The optical absorption is studied by Tauc plot which is instrumental in finding the optical band gap of the material and the refractive index.
Silicon Composite Anodes: Half and Full Cell Studies
Authors: Karulkar Mohan
Published: October 2014

Carbon-silicon (C-Si) composite anode material was fabricated and used to create electrodes. For C-Si half cells, adding a conductive buffer layer of PVDF/graphene improved adhesion and performance. Cycling with capacity control (1000, 900, 400 mAh/g) improved cycle life over full cycling (0.02 – 1.2V). Thinner electrodes (18μm) with larger particles (1000μm2 surface area) displayed the best cycle life. For NMC half-cells, a recipe of 85% NMC, 10% PVDF, 5% C45 (85/10/5) gave the best adhesion, but worst performance. A 96/2/2 recipe gave poor adhesion, but the best performance due to high active material loading. Calendering to 60% of original thickness improved performance by 100%. For C-Si // NMC full cells, a voltage range of 2.8 – 4.3V gave the best cycle life. Anode pre-lithiation for 1 minute gave ~15% capacity improvement without increasing decay rate, while longer pre-lithiation times were detrimental to performance.
High Rate and Long Cycle Life Anodes via Atomic Layer Deposition of Titanium Dioxide Coatings on Mesoporous Activated Carbon
Authors: Xing Weibing , Buettner-Garrett Josh , Krysiak Mike , Kelly Joe , King David M
Published: October 2014

As an anode active material for lithium ion (Li-ion) batteries, titanium dioxide (TiO2) has recently attracted much attention from researchers due to its high theoretical specific capacity, safety characteristics arising from its high electrochemical potential (~1.5V) vs. Li/Li+, low cost, material availability and environmental benignity. However, the low electronic conductivity, sluggish Li+ diffusivity and poor cycle performance of TiO2 have limited its widespread acceptance in practical rechargeable Li-ion batteries. Here, we present a promising method of preparing TiO2 based anodes via atomic layer deposition (ALD) coatings of TiO2 on mesoporous activated carbon (AC) electrodes. TiO2-AC anodes prepared in this study demonstrated remarkable electrochemical performance with drastically increased specific capacity, extremely high rate capability attributed to facile Li+ insertion/extraction of ALD coated, nano-sized TiO2 particles, and excellent cycle performance.
(De)lithiation-Induced Phase Transitions of LiMTiO4 Spinels
Authors: Chen Ruiyong , Knapp Michael , Yavuz Murat , Hahn Horst
Published: October 2014

Nanocrystalline LiMn3+TiO4 (~10 nm, annealed in air at 500°C) and LiFe3+TiO4 (3~5 nm, annealed in argon at 600°C) were synthesized by a sol-gel route, and their structural changes upon Li+ extraction and reinsertion were investigated. To determine accurately the phase compositions of the nanosized materials, we used combined techniques of X-ray diffraction (XRD) Rietveld refinement and synchrotron pair distribution function (PDF) analysis. Partial lithium from LiMTiO4 (M = Mn, Fe) can be extracted on charging to 4.8 V, leading to Li-deficient Li1-x
MTiO4 with a phase splitting into two spinel phases. Over subsequent cycling between 1.5 and 4.8 V, more than one Li+ can be reversibly reinserted into the framework, resulting in a Li-rich Li
x

+y
MTiO4. Upon lithiation, Li1+y
MnTiO4 undergoes a reversible spinel/rock-salt phase transition together with the formation of certain amounts of tetragonal phase, whereas LiFeTiO4 maintains a spinel structure.
Modeling of SEI Layer Growth and Electrochemical Impedance Spectroscopy Response using a Thermal-Electrochemical Model of Li-ion Batteries
Authors: Liu Lin , Zhu Min
Published: October 2014

Lithium-ion batteries (LIBs) suffer severe performance degradation during their lifetime application because of the undesired chemical reactions, ageing, corrosion, structural integrity compromise, and the threat of thermal runaway. Formation of new SEI layer and its growth cause LIBs internal resistance increase and capacity loss, leading to performance degradation. In order to comprehensively investigate the effects of SEI growth on battery performance and cell electrochemical impedance spectroscopy (EIS) response, a one-dimensional thermal-electrochemical model was developed. The model is able to reveal the effects of diffusivity, kinetics, and temperature on SEI layer growth and cell capacity fade. Based on the thermal-electrochemical model developed, one more mathematical model is developed to simulate the impedance response of LIBs with considering the double layer capacitance effect. The simulated impedance response is analyzed to reveal LIBs impedance behaviors, which can be used to predict the degradation mechanism of LIBs. With the layer becoming thicker, its growth rate slows down gradually due to increased diffusion resistance. SEI grows more quickly during charge than discharge due to the difference in electron flux through the SEI layer and the temperature change during cycling. Temperature rise due to reaction and joule heating accelerates the SEI layer growth and causes more capacity loss. This work can provide us the insights of combining LIBs EIS analysis with degradation analysis.
Direct Growth of RuO2 Nano-Architectures on Current Collectors and Their Improved Performance in Lithium-Ion Batteries
Authors: Navulla Anantharamulu , Meda Lamartine
Published: October 2014

RuO2 nano-plate architectures were successfully deposited directly on stainless steel current collectors by low pressure chemical vapor deposition at low temperatures using ruthenocene, Ru(C5H5)2 as the starting precursor without applying any catalyst. As-prepared materials were characterized by powder X-ray diffraction and field-emission scanning electron microscope techniques. Galvanostatic charge-discharge experiments were carried out versus Li-metal. A capacity of 1150 mAh g-1 was observed during the first discharge process. After 20 cycles, the materials stabilizes at 1000 mAh g-1 which represents only a 13% loss in capacity. The improvement in cycle life at high capacity is attributed to the growth process and unique nanostructure of RuO2.
Effect of Controlled Anode Flow Release on Dead-Ended Anode Proton Exchange Membrane Fuel Cells
Authors: Meyer Quentin P.-G. , Ashton Sean , Curnick Oliver , Reisch Tobias , Adcock Paul , Shearing Paul R , Brett Dan J. L.
Published: October 2014

Dead-ended anode operation is commonly used in polymer electrolyte fuel cells, but suffers from voltage reduction with time. This study shows how a controlled anode bleed can mitigate against voltage loss and fuel dilution. Performance analysis, along with off-gas analysis, is used to characterize cell performance during dead-ended mode and an optimum bleed rate is identified to minimize voltage drop for this particular 5-cell stack.
An Electrochemical Investigation on Additives to the Controllable Electro-Healing Cracks in Nickel
Authors: Zheng Xiangui , Shi Yinong , Lu Ke
Published: October 2014

In the present work, polyethyleneimine (PEI), 2-mercapto-5-benzimidazolesulfonic acid (MBIS), MBIS and thiourea (TU) were added respectively to the conventional Watts bath to investigate the controllable electro-healing on pure Ni plate with a through thickness crack. It is demonstrated that PEI has a strong inhibition effect on the Ni reduction, which resulted in the formation of large visible defects along the interface between the substrate and the healing crystals. MBIS has a similar inhibition effect on Ni reduction, but with a promoted current efficiency. The addition of TU to the MBIS added solution depolarized the Ni reduction, resulting in an enhanced growth of healing crystals from sidewalls of the crack.
Electrochemical Formation of RE-Zn (RE=Dy, Nd) Alloys in a Molten LiCl-KCl System
Authors: Konishi Hirokazu , Ono Hideki , Takeuchi Eiichi , Nohira Toshiyuki , Oishi Tetsuo
Published: October 2014

The electrochemical formation of RE-Zn (RE=Dy, Nd) alloys were studied in LiCl-KCl-RECl3 (0.50 mol% added) at 653 K. The electrochemical behavior of Dy (III) was investigated by cyclic voltammetry using a Zn wire as a working electrode in a molten LiCl-KCl-DyCl3. Cathodic current was observed from 1.10 V. Since this potential is more positive than Dy metal deposition potential, the cathodic current corresponds to the formation of Dy-Zn alloys. Potentiostatic electrolysis at 0.70 V for 1 h using a Zn electrode resulted in formation of the dense and coherent DyZn3 film with the thickness of about 30 µm in a molten LiCl-KCl-DyCl3. Finally, alloy samples were prepared by potentiostatic electrolysis at 0.80-1.20 V for 1 h using Zn plates in a molten LiCl-KCl-DyCl3-NdCl3. The mass ratio of Nd/Dy in the alloy sample was found to be 3.3 at 1.00 V by ICP-AES.