bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Printed Carbon Nanotube Sensor on a Flexible Substrate
Authors: Tortorich Ryan P. , da Costa Tallis H. , Song Edward , Choi Jin-Woo 
Published: February 2020

Printing becomes an emerging manufacturing technology for mechanics, electronics, and consumer products. Carbon nanotubes have recently been used as a material for sensors and electrodes due to their unique electrical and mechanical properties. Printed electrodes and conductive traces particularly offer versatility of fabricating low-cost, disposable, and flexible sensors and devices. While screen-printing has been a conventional method for printing conductive traces and electrodes, inkjet-printing recently attracts a wide attention due to its unique advantages including no template requirement, rapid printing at low cost, on-demand printing capability, and precise control of the printed material. Computer generated conductive trace or electrode patterns can simply be printed on a flexible substrate with proper conductive ink. However, for inkjet-printing of nanotubes to form conductive traces and electrodes, there are few challenges that need to be addressed. One is nanotube dispersion in an ink base solution while others include adjusting surface tension and controlling viscosity of the ink and treating the surface of the printing substrate. This work presents carbon nanotube ink preparation and its demonstration in chemical sensing along with our recent achievements.
It is essential to disperse carbon nanotubes to make a carbon nanotube ink. In our previous work, we have demonstrated an inkjet printed electrochemical sensor using an office HP inkjet printer and a carbon nanotube ink. Sodium dodecyl sulfate (SDS) was used as a dispersant and a surfactant in preparing the carbon nanotube ink. It should be noted that that a ratio of SDS concentration and carbon nanotube concentration would be an important factor determining the sheet resistance of a printed carbon nanotube pattern. A preliminary test result confirmed that there would be an optimum SDS:CNT ratio. For flexible sensor applications, sheet resistance change of the printed carbon nanotube patterns on a flexible substrate was measured for varying curvatures of the substrate. For a curvature up to 0.36 cm-1, the sheet resistance increase was less than 2.5% showing that the printed carbon nanotube patterns could be used for a flexible and printed sensor. Using the developed technologies, a fully printed carbon nanotube sensor on a flexible substrate will be demonstrated for chemical and biological sensing.
Application of a Methodology Combining Predictive and Descriptive Models to Describe the Influence of the Temperature on the Passive Film Steady State
Authors: Boissy Clément , Ter-Ovanessian Benoît , Normand Bernard 
Published: February 2020

Passive materials are working in more and more severe conditions. By example, the development of the Proton Exchange Membrane Fuel Cell – PEMFC, leads to the used of stainless steel in higher temperature to improve the energetic efficiency. The main issue understanding the passivation process lies with the multiplicity of the phenomena modifying the behavior of the film. As describe into the Point Defect Model - PDM, the electrochemical reactions occurs at the metal/oxide interface and the oxide/solution interface. The reactivity is limited by mass transport through the oxide. Although, this phenomenon is slow because occurring into a solid phase, it could be observable by electrochemical impedance spectroscopy at regular frequencies because of a very thin oxide.
A methodology was developed to study this transport phenomenon combining the use of the PDM with a descriptive model to analyze experimental data from electrochemical impedance spectroscopy. The evolution of the main charge carrier density vs. the formation potential of the oxide is studied and according to the PDM the diffusion coefficient of the point defect through the oxide is determined. Knowing the thickness of the oxide, by means of X-ray Photoelectron Spectroscopy, the time constant of the transport is determined. Based on this value, a descriptive model is selected avoiding the over-parameterization of the EIS data.
In this way the combination of a predictive model and a descriptive one is used to objectively take into account the transport phenomena without using an over-parameterized model. This methodology is used in acidic solutions at several temperatures on two materials. Pure chromium is studied as model material and 316L as an industrial one. The conditions which leads to the consideration of the mass transport in the electrochemical impedance analysis are discussed. At higher temperature, the study of the mass transport seems to be necessary.
Considerations in the Internal Corrosion Mitigation
Authors: Pedraza Basulto Gabriela Karina , Ortega Dulce , Carrillo Irene , Cantó Jorge , Martinez Lorenzo 
Published: February 2020

Corrosion is an important dominant contributing factor to failures and leaks in pipelines. It´s important that to deal with this issue, there is recommended practices to improve and maintain the mechanical integrity of upstream pipelines. They are intended to assist ups tream oil and gas producers in recognizing the conditions that contribute to pipeline corrosion incidents, and identify effective measures that can be taken to reduce the likelihood of corrosion incidents.
These factors could be low velocity and poor pigging practices allow water to stagnate in the pipelines, CO2 dissolves in water to form carbonic acid, Corrosion rates increase with increasing CO2 partial pressures for example.
This document addresses design, maintenance and operating considerations for the mitigation of internal corrosion in oil pipeline systems.
Evaluation at Pipeline Corrosion at Oil Field
Authors: Pedraza Basulto Gabriela Karina , Ortega Dulce , Carrillo Irene , Cantó Jorge , Martinez Lorenzo 
Published: February 2020

It is important to know that the Petroleum industry contains a wide variety of corrosive agents . Some of these, many are unique to this industry. Thus it is opportune to group all these environments together. Corrosion problems occur in the petroleum industry in at least three general areas: production, transportation and storage, and refinery operations.
In spite of Internal corrosion of product pipelines can be controlled with coatings and inhibitor, such as amines and nitrites. The various aggressive agents shall be determined through monitoring of the physical and chemical characteristics of the fluid in contact with the system under study, providing aggressive conditions thereof. The most important elements to be determined are: Gases dissolved in water and gas (H2S, CO2 and O2), Bacteria sulfatoreductoras , Chlorides , pH.
The aim of this work is make the characterization of the fluid and determinate the corrosivity of them in a transportation pipeline. The results show us the scale of priorization of them as well as a results of the gravimetric tecniques.
Evaluation of Corrosion T22 and 347H Steel Molten Salt By Electrochemical Techniques
Authors: Estrada Ariadna Trujillo , Miramontes Jose Angel Cabral , Robledo Patricia Zambrano , Tiburcio Citlalli Gaona , Calderón Facundo Almeraya 
Published: February 2020

INTRODUCTION
The main applications of the SA213 and SA213-TP347H-T22 steels are in aggressive environments such as molten salts, the concentration of these along with the temperature increase generated in the corrosion rate [1-3].
METHODOLOGY
The electrochemical cell used consists of a working electrode WE1, a reference electrode and an auxiliary electrode RE AU in a molten salt electrolyte consisting of 50% V2O5 - 50% Na2SO4 at 700 ° C.
RESULTS
Current I [mA/cm2] and Potential time series [mV/cm2] were obtained to evaluate the behavior of both steels in time, and determine the type of damage caused by molten salts [1,2]. In Figure 1 two sets of time are shown in current for two types of steel.
CONCLUSIONS
Behavior TP347H SA213-SA213-T22 and corrosive attack at high temperature by means of electrochemical noise was evaluated.
The results of electrochemical noise are processed in the frequency domain [4] results acquiring noise impedance Zn.
REFERENCES
[1] Almeraya, F., A. Martinez-Villafañe, C. Gaona, M. A. Romero, and J. M. Malo. Revista de metalurgia 34, no. 1 (1998): 11-17.
[2] Tristancho, José Luis, Facundo Almeraya, and José Chacón. Scientia et Technica 3, no. 46 (2010): 163-167.
[3] Wood, Graham C. Oxidation of Metals 2, no. 1 (1970): 11-57.
[4] J. Botana-Pedemonte, A. Aballe-Villero, M. Marcos-Bárcenas. SEPTEM Ediciones, Oviedo España (2002).
Investigating the Role of Electrolyte Composition and Oxide Structure in Galvanic Corrosion Susceptibility Under Atmospheric Electrolytes
Authors: Policastro Steven , Hangarter Carlos M , Martin Farrel J 
Published: February 2020

The goal of this study is to develop a better mechanistic understanding of how electrolyte composition and surface oxides can influence corrosion kinetics in the electrolytes formed from atmospheric processes. It has been observed that galvanic couples between aluminum alloys and titanium or stainless steel fasteners exposed to electrolytes formed from atmospheric processes lead to very different corrosion rates (Z. Feng, G. Frankel, Corrosion, 70(2014) pgs 95-106).
In order to collect the data necessary to accomplish this goal, sixteen 2”x2” panels of AA2024, AA7075, CRES 13-8, CRES 17-4, Ti-6Al-4V, and Custom 465 were cut from panel or bar stock and polished to 600 grit SiC. The samples were then mounted in 300 mL Gamry Paracells and exposed for 18 hours to the following electrolytes: 0.6M NaCl at ambient aeration, 6M NaCl at ambient aeration, deoxygenated 0.6M NaCl saturated with nitrogen,0.6M NaCl + 0.01M HCl, 0.6M NaCl + 0.01M H2SO4, and 0.6M NaCl + 0.005M HNO3 + 0.005M H2SO4. The aluminum alloys were then anodically polarized at 0.167 mV/sec from -0.02V below EOC to + 1.5VSCE. The other alloys were polarized cathodically at 0.167 mV/sec from +0.02V above EOC to -1.4VSCE. Results for the cathodic polarization scans of the CRES 13-8PH stainless steel and the Ti-6Al-4V titanium alloy are shown in Figure 1.
The differences in cathodic current capacity for materials exposed to the same electrolyte at the same aeration level reinforces the fact that oxide microstructure plays a significant role in catalyzing reduction reactions, though the kinetics of the reaction rates may not be predicted from a simple galvanic series. Of more interest are the changes in reaction rates from acidification of the electrolyte. This suggests that the electrolyte is changing the the oxide microstructure or that new reduction reactions are supported. This is significant because overlays of the anodic polarizations of the aluminum alloys indicate that material loss rates can be orders of magnitude higher for acidified atmospheric electrolytes. These effects are being investigated using microelectrode experiments on droplets of the various electrolytes along with supporting experiments using Scanning Kelvin Probe techniques.

Acknowledgements

The authors gratefully acknowledge the financial support of the Office of Naval Research

Figure 1: Cathodic polarization curves for the titanium alloy Ti-6Al-4V and the stainless steel CRES 13-8PH in 0.6M NaCl and 0.6M NaCl + 0.005M H2SO4 + 0.005M HNO3, showing that materials with different surface oxides and in near-neutral to low-pH electrolytes can support very different cathodic reaction rates with potentially very deleterious consequences for galvanic couples with more active materials.
Hybrid Electrocatalysts of NiMo and Molybdenum Sulfide for Hydrogen Evolution Reaction
Authors: Lee Kyu Hwan , Chang Doyon , Lim Jae-Hong , Lim Dongchan , Choi Sung Mook , Lee Joo Yul , Myung Nosang Vincent 
Published: February 2020

The best known catalysts for the hydrogen evolution reaction (HER) are platinum group precious metals, but the scarcity and high cost of these materials prohibit their wide-scale deployment.
As a alternatives, nickel-based alloy (NiMo, NiW, NiFe etc.) catalysts show high electrocatalytic activity for HER, but they often degrade in acidic solutions.
Recently, Molybdenum sulfides nanomaterials have drawn great attention due to their low cost, high chemical stability, and excellent photocatalytic and electrocatalytic properties in HERs. They are potentially useful if they can be tailored for the development of hydrogen energy devices. In order to enhance the efficiency of inorganic catalysts, many research efforts have been made toward the modification of material properties, the formation of composite catalysts, and the fabrication of the electrodes with nano-architecture.
In this paper, we will show the hybrid electrocatalysts of NiMo nanoparticles and molybdenum sulfide thin films for HER, showing high activity and stability. The main purpose of this work is to draw the synergetic effect of NiMo's high activity and high electrical conductivity and molybdenum sulfide's high activity and high chemical stability.
We synthesized NiMo nanoparticles and molybdenum sulfide thin films with various compositions. The electrodeposited molybdenum sulfide films had amorphous structure of MoSx and/or MoOSx. The electrochemical and spectroscopical analysis to understand the catalytic activity of hybrid catalysts will be discussed.
Computational Modelling of Cation Contamination in PEFCs
Authors: Uddin Md. Aman , Pasaogullari Ugur , Molter Trent 
Published: February 2020

Polymer electrolyte membrane (PEM) is a key component of polymer electrolyte membrane fuel cell (PEFC). It is vulnerable to cationic impurities that are present in the air and fuel stream or that may have originated from the cell, stack or balance of plant components. Almost all foreign cations have higher affinity to sulfonic acid group than proton and the presence of foreign cation in the membrane or catalyst layers results in reduced ionic conductivity, increased electro-osmotic drag, and reduced water content (1).
In this study, a steady, one dimensional cation (Na+) contamination model of membrane electrode assembly (MEA) of PEFC (shown in figure 1) is developed by solving the coupled transport phenomena related to the foreign cation, water, and oxygen. Concentrated solution theory is utilized to solve the cation transport equation based on Serincan et al.’s model (2) and dilute solution theory for water, hydrogen, and oxygen transport. A spherical agglomerate model is considered in the cathode catalyst layer (CCL) to describe effects of foreign cations in the catalyst layer. To separate the effects of cations on different transport phenomena, first no contamination case is solved and then contamination effects are added one by one to the cation transport, water transport, and oxygen transport and finally to the Nernst equation.
Cation (Na+) contamination in the air stream found to cause several detrimental effects on the performance of PEFC. The main effects are: (a) cation replaces proton and occupies sulfonic acid sites in ionomer. It can occupy up to 96% sites in the cathode catalyst layer (CCL); (b) It causes serious water depletion in the ionomer due to decrease in water diffusivity; (c) It decreases the oxygen diffusivity causing a decrease in dissolved oxygen concentration in CCL; and (d) It decreases the open circuit voltage (OCV) in CCL due to reduction in proton concentration in the ionomer phase. These contamination effects on each parameter decrease the protonic current density and combined effects result in a reduction of current density from 0.72 A/cm2 to 0.25 A/cm2at a cell voltage of 0.7 V (shown in figure 2).

Acknowledgements

The authors are grateful for the financial support of the Department of Energy (DOE)-EERE, DE-EE00000467 (University of Hawaii, prime contractor, Jean St-Pierre, PI).

References

1. T. Okada, in Handbook of Fuel Cells, Cells– Fundamentals, Technology and Applications., W. Vielstich, H. A. Gasteiger, A. Lamm and H. Yokokawa. Editors, John Wiley & Sons, Ltd (2010).

2. M. F. Serincan, U. Pasaogullari and T. Molter, Int J. Hydrogen Energy,
35, 11 (2010).
Polymer Electrolyte Membrane Fuel Cells: Characterization and Diagnostics
Authors: Dhanushkodi Shankar , Schwager Maximilian , Mérida Walter 
Published: February 2020

The normal operation of proton exchange membrane fuel cells (PEMFCs) can induce significant temperature, humidity, pressure or concentration gradients across the cell’s active area. The overall performance and stability can be affected negatively by these gradients. For example, localized transient changes in environmental conditions may contribute to material degradation, and ultimately, to cell failure.
We report on new diagnostic techniques and methodologies that have been developed to characterise PEMFC material properties, and the inhomogeneities across the active area of a working cell. Specifically, we will describe ex situ techniques for membrane electrode assembly (MEA) materials characterisation, and in situ techniques for the spatially resolved characterization of PEMFC performance. These techniques incorporate independent control over local potentials with concurrent membrane water content characterization (via high-frequency resistance measurements). Our testing hardware features sixteen fully isolated segments over a 42 cm2 active area, reference electrode capabilities, and individual segment control. This configuration enables the measurement of localised anode and cathode overpotentials separately.
The technique’s versatility will be illustrated by effective platinum surface area (EPSA) measurements across the active under accelerated stress tests (ASTs) conducive to platinum dissolution. Each segment in a membrane electrode assembly was exposed to 10,000 cycles of Pt dissolution AST separately. The beginning-of-life EPSA was calculated via cyclic voltammetry, and the catalyst layer morphology and properties were found to change during the AST. Impedance measurements were obtained in H2/N2 conditions in order to map the ionic conductivity and the polarization resistance of the catalyst layer across the segmented cell. Higher EPSA and performance loss were observed in segments near the fuel cell outlet compared to those near the reactant inlets.
Kinetics of Sodium Borohydride Hydrolysis at the Cobalt with a Fiber Structure Modified with Gold Nanoparticles
Authors: Norkus Eugenijus , Balciunaite Aldona , Lichusina Svetlana , Simkunaite Dijana , Stalnioniene Irena , Zieliene Albina , Vaiciuniene Jurate , Selskis Algirdas , Tamasauskaite-Tamasiunaite Loreta 
Published: February 2020

Among chemical hydrides sodium borohydride is widely used as a source for a hydrogen generation during its catalytic hydrolysis. This attention is determined by its features such as a high hydrogen storage capacity, nontoxicity, good storability, easily controlled hydrogen generation rate. The development of new catalysts with high activity in the hydrolysis reaction of borohydride and durability plays an important role in the hydrogen generation for fuel cells.
This work presents the study of catalytic activity of cobalt with a fiber structure deposited on the copper surface and modified with gold nanoparticles towards the hydrolysis of borohydride. Cobalt coatings with the thickness of ~3 µm were deposited from the electrolyte described in Ref. [1]. Au crystallites were deposited on the Co/Cu surface (denoted as Au(Co)/Cu) via the galvanic displacement technique. The Co/Cu catalysts were immersed into the 1 mM HAuCl4 + 0.1 M HCl solution at 25 oC for 0.5, 1 and 5 min, respectively [2]. The morphology, structure and composition of the prepared catalysts were examined by means of Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, X-ray diffraction and Inductively Coupled Plasma Optical Emission Spectroscopy.
It has been determined that the Au loadings were 10.8, 22.4 and 84.4 µg cm-2 in the prepared Au(Co)/Cu catalysts after the immersion of Co/Cu into the gold-containing solution for 0.5, 1 and 5 min, respectively. The data of hydrogen generation from an alkaline sodium borohydride solutions using the Co/Cu and different Au(Co)/Cu catalysts under various conditions are presented.
It has been determined that the temperature and amount of catalysts have exceptional influence on the rate of hydrogen generation from alkaline sodium borohydride solutions.

References

[1] E. Juzeliunas, S. Lichusina. Patent of the Republic of Lithuania No. 5481 26.03.2008.
[2] L. Tamasauskaite-Tamasiunaite, A. Jagminiene, A. Balciunaite, A. Zabielaite, J. Vaiciuniene, A. Selskis, R. Juskenas, E. Norkus. Int. J. Hydrogen Energy 38 (2013) 14232-14241.
Study of Azoles as Bifunctional Additives for Proton Exchange Membranes Melt-Processing from LSC and SSC Perfluorosulfonic Acid Ionomers
Authors: Mokrini Asmae 
Published: February 2020

This work investigates the potential use of azoles as bifunctional additives for proton exchange membranes (PEM) manufacturing through direct melt-processing of acidic ionomers. The development of high-volume manufacturing processes to prototype PEM fuel cell components with a reduced number of steps is vital to reduce system cost and complexity, and to meet the demands of high volume production and durability requirements especially for automotive applications.
The strong ionic associations in ionomers act generally as physical cross-links, increasing by several orders of magnitude both melt-viscosities and relaxation times, resulting in ionomeric materials that are very difficult to melt-process with high shear rate processes such as melt-casting or melt-blowing. The strength of the ionic interactions in ionomers, and hence their physical and mechanical properties, depends on the acidity of the pendent anion. Polymers modified with the stronger acid, such as sulfonic acid (pKa~1), exhibit more dramatic changes in thermal, viscoelastic, and rheological properties than those modified with the weaker carboxylic acid (pKa~4-5). However, most ionomers may be melt-processed in very low shear rate operations such as compression-molding, which reveals that these ionic associations are not permanent cross-links and can be reversibly disrupted under suitable conditions.
The approach investigated is based on the use of selected bi-functional additives that act as a SO3H groups protection and a melt-processing aid.[1] The additives selected are highly polar additives with relatively high boiling points that are expected to interact with the ion-rich aggregates that compose the nanophase separation in ionomers and act as plasticizers which expectantly improve the viscoelastic behavior during melt processing. Additives from the azole family, imidazole, 1,2,4-triazole and benzimidazole have been investigated as potential bifunctional additives. This presentation, will discuss the results obtained with four commercial PFSA ionomers Nafion® DE-2020 and NR-40 with long side chain (LSC), and Aquivion® D83-24B and D79-20BS with short side chain (SSC).

Figure 1. melt-processed samples of Aquivion® D79-20BS a) no additive, b) with 2 mol of imidazole/mol of SO3- and c) with 2 mol of 1,2,4-triazole/mol of SO3-

[1] US patent application 61/767,849 "PROCESS FOR PRODUCING ION EXCHANGE MEMBRANES BY MELT-PROCESSING OF ACIDIC PFSA IONOMERS"