bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of 3D-Printed Fuel Cells and Stacks
Authors: Gould Benjamin D. , Rodgers Joseph A. , Schuette MIchael , Bethune Keith , Louis Shaquille , Rocheleau Richard , Swider-Lyons Karen 
Published: February 2020

3D-printing, a.k.a. additive manufacturing (AM), has become a popular topic in the general public and in industry [1]. There is recent interest in using AM to fabricate fuel cell components because of AMs ability to build metal parts with complex geometries with relatively short lead times [2]. Fuel cell bipolar plates (BPPs) require complex internal passageways for coolant flow fields making them a good candidate for AM. By building one piece BPPs the number of parts, the number of seals and the complexity of assembly can be decreased.
We present the performance characteristics of a 400W fuel cell system made with BPPs made of Ti-alloy (Ti-6Al-4V) and built by 3D-printing. The BPPs are made by direct metal laser sintering (DMLS) and are coated by Treadstone Inc. with Au-microdots and a TiO2layer to decrease contact resistance and protect against corrosion. Titanium alloy is examined because of its high strength-to-weight ratio which makes it an ideal material for aerospace applications. This work extends our previous work regarding the contact resistance of 3D-printed metal BPPs to include functional fuel cell stacks [3]. The performance characteristics of single cells and stacks will be discussed in the context of surface finish, flatness, feature tolerance, weight, cell-to-cell variability, scaling and contact resistance.
Overall DMLS is an exciting new technique with great promise for future rapid prototyping of BPP designs and many other fuel cell components. However, greater advances in surface finish, feature thinness and flatness are needed before BPPs built by 3D-printing will compete with the traditional machined or formed BPPs.

References

[1] http://techland.time.com/tag/3d-printing/ (2014)
[2] http://energy.gov/eere/articles/doe-announces-webinars-natural-gas-biomass-technologies-additive-manufacturing-fuel. (2014)
[3] C. J. Netwall, B. D. Gould, J. A. Rodger, N. J. Nasello, K. E. Swider-Lyons, J. Power Sources, 227, 137 (2013).
Gold-Metal (Ni, Cu) Deposited on the Titania Nanotubes as Electrocatalysts for Borohydride Oxidation
Authors: Balciunaite Aldona , Stankevičienė Ina , Zabielaite Ausrine , Vaiciuniene Jurate , Selskis Algirdas , Juskenas Remigijus , Tamasauskaite-Tamasiunaite Loreta , Norkus Eugenijus 
Published: February 2020

In the present work the optimization of the preparation of titania nanotube supported Au-Ni and Au-Cu catalysts (denoted as Au(Ni)/TiO2-NTs and Au(Cu)/TiO2-NTs) via the galvanic displacement technique is presented. The catalysts were prepared according the following procedures: i) preparation of TiO2 nanotube arrays by anodization of titanium sheets in an aqueous sulfuric acid solution containing some NH4F; ii) deposition of an electroless Ni or Cu sublayers on the synthesized TiO2 nanotube arrays [1-3] and iii) subsequent immersion of the Ni/TiO2-NTs or Cu/NiTiO2-NTs electrodes into the gold-containing solution for various time periods. The morphology and composition of the 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. The electrochemical behavior and electrocatalytic activity of the fabricated catalysts towards borohydride oxidation were measured by means of cyclic voltammetry. The electroactive area of gold surface created on fabricated catalysts was determined from cyclic voltammograms of Au/TiO2-NTs electrodes recorded in a deaerated 0.5 M H2SO4 solution at a scan rate of 10 mV s-1.
The prepared Au(Ni)/TiO2-NTs and Au(Cu)/TiO2-NTs electrodes exhibited a high catalytic efficiency towards the oxidation of borohydride when compared to that of bulk Au electrode. A higher catalytic activity of the prepared Au(Ni)/TiO2-NTs and Au(Cu)/TiO2-NTs catalysts under various conditions may be related to production of smaller gold nanoparticles and their fine and uniform dispersion on the surface.
The Au-Ni and Au-Cu catalysts deposited on the titania nanotube surface seem to be a promising anodic material for direct borohydride fuel cells.

Acknowledgement

This research was funded by a grant (No. ATE-08/2012) from the Research Council of Lithuania.

References

[1] L. Tamasauskaite-Tamasiunaite, A. Balciunaite, D. Šimkunaite, A. Selskis. J. Power Sources 202 (2012) 85-91.
[2] L. Tamasauskaite-Tamasiunaite, A. Balciunaite, R. Cekaviciute, A. Selskis. J. Electrochem. Soc. 159 (2012) B611-B618.
[3] L. Tamasauskaite-Tamasiunaite, A. Balciunaite, A. Zabielaite, I. Stankeviciene, V. Kepeniene, A. Selskis, R. Juškenas, E. Norkus. J. Electroanal. Chem. 700 (2013) 1-7.
Statistical and Block Copolymers for Anion-Exchange Membranes with High Local Concentrations of Quaternary Ammonium Groups
Authors: Weiber E. Annika , Jannasch Patric 
Published: February 2020

Cationic polymers in the form of anion-exchange membranes (AEMs) may enable a route towards low platinum or even platinum-free alkaline membrane fuel cells with the potential to oxidize more complex fuels than hydrogen and methanol [1-4]. The main challenges for the AEMs are currently to enhance the alkaline stability of the cationic group and to improve the ion conductivity. In this context, there have been many attempts to enhance the properties by varying the backbone polymer structure and the nature and content of the cations [1-4]. However, clearly promising strategies to prepare high-performance AEMs have not yet been described. While several lessons can be learnt from the development of proton-exchange membranes (PEMs), the cationic polymers in AEMs have different characteristics. For example, the organic cations of AEMs, such as quaternary ammonium (QA) groups, are larger and have a lower propensity to cluster and form a distinct ionic phase in the polymer matrix in comparison with the sulfonic groups of PEMs. This characteristic may seriously limit the transport properties of AEMs.
We have recently developed synthetic strategies where single phenylene rings in aromatic polymers can be directly functionalized with precisely two, three, or four QA groups, allowing an excellent and systematic control over the local density and distribution of ionic groups along the polymer backbone. We have used this approach to prepare several series of statistical and multiblock copolysulfones with very high local QA concentrations to promote membrane properties. Small angle X-ray scattering of AEMs based statistical copolymers containing phenylene rings functionalized with two, three and four QA groups, respectively, showed clear ionomer peaks to indicate efficient ionic clustering. The clustering was promoted by an increasing density of QA on the single phenylene rings. Corresponding randomly functionalized copolymer membranes showed no ionomer peaks. At moderate ion-exchange capacities, the Br- conductivity of the densely functionalized copolymers was higher than that of randomly functionalized copolymers, despite a significantly higher water uptake of the latter. In the current presentation, we will discuss selected results on the synthesis and structure-property relationships of the copolymers and AEMs.

References

[1] M. A. Hickner, A. M. Herring, E. B. Coughlin, J. Polym. Sci., Part B: Polym. Phys.,
2013, 51, 1727.
[2] J. R. Varcoe, R. C. T. Slade, Fuel Cells, 2005, 5, 187.
[3] N. Li, M. D. Guiver, Macromolecules, 2014, online DOI: 10.1021/ma402254h.
[4] K. D. Kreuer, Chem. Mater.,
2014, 26, 361.
Effect of the Inlet Gas Humidification on PEMFC Behavior and Current Density Distribution
Authors: Sanchez Daniel G , Ruiu Tiziana , Biswas Indro , Friedrich K. Andreas , Sanchez-Monreal Juan , Vera Marcos 
Published: February 2020

Water management represents one of the main challenges in the design and operation of PEMFCs. The influence of inlet gas humidification on cell performances is analyzed in general and especially the effect of low humidity conditions in both cathode and anode is studied. Hereby in situ diagnostic tools like EIS and current density measurements are used.
Dry cathode air supply and a fully humidified anode gas stream lead to a periodic transition between low- and high-current cell operations. A review of the main variables involved in this phenomenology is given. Furthermore, this oscillatory behavior is used as a tool to study degradation processes.

Figure1 Overall cell current density oscillations (symbols) and current density distributions at the low current (lower inset) and high current (upper inset) states of a single PEM cell operated with dry cathode air supply (RHc=5%) and a fully humidified anode gas stream (RHa=100%); Cell voltage= 600mV, Flow H2= 209 ml·min-1, Flow Air= 664 ml·min-1, Pressure= 1.5 bar,Tc=80°C
Fracture Properties of Fuel Cell Membranes
Authors: Singh Yadvinder , M.H. Khorasany Ramin , Alavijeh Alireza Sadeghi , Kjeang Erik , Wang Gary , Rajapakse Nimal 
Published: February 2020

Understanding the crack propagation behavior of common perfluorosulfonic acid (PFSA) ionomer membranes under hygrothermal and mechanical cyclic loading is of vital significance in designing more durable fuel cell stacks (1). Hence, we have developed a test procedure to shed light on the crack propagation characteristics of membranes as a function of loading and environmental conditions. Rectangular specimens with a width of 10 mm and cracks with an average length of 0.7 mm on both sides are used. The specimens are placed under cyclic mechanical loading in a controlled level of environmental conditions (temperature and humidity). The crack propagation rate in the membrane is measured as a function of temperature, humidity and the amplitude of mechanical loading (Figure 1). It is found that a small linear decrease in the magnitude of the force results in an exponential decrement in the crack propagation rate. Furthermore, for a given state of mechanical load, it is found that increasing the relative humidity and/or temperature can significantly increase the crack propagation rate.
In a parallel study, a fracture mechanics-based model capable of simulating the in-situ crack initiation and propagation in the membrane during fuel cell operation is also developed. The elastic-viscoplastic nature of PFSA membranes is well-established in (2). A finite element method (FEM) based constitutive model that can simulate this behavior is used to relate the stress and strain at different environmental conditions (3). Numerical simulations reveal the presence of cyclic mechanical stresses within the membrane due to dynamic hygrothermal conditions present in a running fuel cell that can cause the initiation and propagation of cracks through mechanical membrane degradation. The dynamic stress-field thus obtained is coupled with the fracture mechanics model. In-situ test cases for various temperature, humidity and strain rate conditions are run to fully understand their effect on crack propagation rates and ultimate failure of the membranes.

Acknowledgements:

This research is supported by Ballard Power Systems and the Natural Sciences and Engineering Research Council of Canada through an Automotive Partnership Canada (APC) grant.

References

1. R. Borup, J. Meyers, B. Pivovar, Y. S. Kim, R. Mukundan et al, Chem. Rev.
107 3925 (2007).
2. M.A. Goulet, R.M.H. Khorasany, C. De Torres, M. Lauritzen, E. Kjeang, G.G. Wang, N. Rajapakse, J. Power Sources
234 38 (2013).
3. R.M.H. Khorasany, M.A. Goulet, A.S. Alavijeh, E. Kjeang, G.G. Wang, R.K.N.D. Rajapakse, J. Power Sources
252 176 (2014).
In-Situ Raman Spectroscopy Probing of Solid Oxide Electrolysis Cells
Authors: Manerova Jevgenija , Cumming Denis J , Sinclair Derek C , Elder Rachael H 
Published: February 2020

Solid oxide electrolysis cell (SOEC) technology is a promising route for sustainable recycling of carbon dioxide and steam into synthetic fuels and commodity chemicals via syngas (H2+ CO) production. This technology is based on the reverse polarity of the prominent solid oxide fuel cell (SOFC) and commonly consists of a porous Ni/YSZ cathode, dense YSZ electrolyte and porous LSM/YSZ anode.
High temperature co-electrolysis of CO2 and H2O is a complicated process and has not yet been fully understood. This is due to a number of reactions that take place simultaneously: water electrolysis, carbon dioxide electrolysis and the reverse water-gas shift reaction (rWGS CO2 + H2 ↔ CO + H2O). Other possible reactions driven by the equilibrium may include the Bosch reaction (CO + H2 ↔ C(s) + H2O) and Boudouard reaction (2CO ↔ CO2 + C(s)).
Carbon deposition on the nickel-cermet surface of SOECs can severely degrade the performance of the cell by deactivating the reaction sites. Recent work by Tao et al. has shown that, at high current densities and conversion efficiencies of CO2 and H2O to CO and H2, carbon formation on the surface of Ni/YSZ fuel electrode is likely to occur [1].
SOECs are typically analyzed in-situ using electrochemical impedance spectroscopy and current-voltage characteristics and ex-situ using scanning electron microscopy to obtain information about cell’s surface topography and composition. However, these techniques are not able to provide conclusive information about the processes occurring during operation of the cell.
In this work we aim to use in-situ Raman spectroscopy alongside traditional electrochemical techniques to probe the surface species of the SOEC electrodes for carbon impurities deposition and provide insight into the fundamental processes and reaction pathways that occur during high temperature (700 – 850 oC) co-electrolysis of CO2 and steam. In-situ Raman spectroscopy is also applied to characterize structural changes and material transformations during SOEC operation.
The particular area of interest is the triple phase boundary (TPB), where the electrochemical reactions take place. Accessing the TPB is challenging due to high operation temperatures and the depth of laser penetration into the sample.
The experimental setup with optical access for the Raman microscope will be discussed in detail as well as the correlation of in-situ spectroscopic data with the electrochemical information obtained from the SOECs.

References

[1] Tao Y., S. D. Ebbesen, and M. B. Mogensen, 2014, J. Electrochem. Soc. 161 (3), F337 – F343.
Sample Preparation Method to Measure Strain of P-Channel with Esige by Nano Beam Diffraction
Authors: Lee Kilho 
Published: February 2020

The quantitatively analysis of embedded SiGe (eSiGe) strain was performed by nano beam diffraction (NBD). We have confirmed the best condition of sample preparation for the NBD measurement for strained p-MOSFET. The thickness of sample must be thick enough to prevent stress relaxation by electron beam.
As a result, we could obtain very stable strain variation ±0.1% at unstrained silicon(Si) region.
We also found that damaged layer caused by focused ion beam (FIB) milling process have a crucial role
in the NBD measurement.
Thus, low energy FIB milling condition was optimized for reducing surface damaged layer of the
specimen. We have found the best sample conditions, thickness above 260nm and low energy FIB milling
for sample preparation.
I. INTRODUCTION
II. EXPERIMENTAL
III. RESULTS AND DISCUSSIONS
3.1 Strain relaxation on sample thickness
3.2 Strain sensitivity related to damaged layer
3.3 Strain profile at p-channel with eSiGe
‡W. Conclusion
Study of the Substrate Effect in the KCl Adsorption onto Single-Crystal and Polycrystalline Gold Electrodes
Authors: Gomez-Zamudio Felipe , Alvarez-Casillas Cesar , Soto-Estrada Adriana , Casillas Norberto , Barcena-Soto Maximiliano , Larios-Duran Erika Roxana 
Published: February 2020

Electron transfer kinetics in electrochemical systems is ubiquitous to natural and industrial processes. Thus a deep knowledge of all stages involved in the charge transfer at the electrode solution interface, which includes mass transport, adsorption and the role of the electrical double layer is highly desirable [1]. In particular, adsorption and the electrical double layer play a distinctive role in the charge transfer at electrode/solution interfaces, since they are essential part of reaction mechanisms, especially for reactions where more than one electron is transferred. Fueled by the importance of adsorption and the electric double-layer in the electrode kinetics, there has been published in the literature several works, but mainly focused on thermodynamic rather than kinetics [2-4].
Here a qualitative study of the effect of the substrate and surface heterogeneities in the adsorption of chloride ions on gold surfaces is presented. With this goal in mind, we have performed a study of the adsorption of chloride ions at different concentrations (1 mM, 10mM 0.1M) disolved in HClO40.5 M on the surfaces of polycrystalline (pc) and gold (111) single crystal. Our results include the characterization of the system by using classic electrochemical techniques, such as cyclic voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and the novel intermodulated techniqued called Interfacial Capacitance Modulation (MIC) [5].
Figure 1 shows a comparison between the typical voltammetric responses as well as the double-layer capacitance vs. polarization behavior for polycristalline and (111) gold electrodes in contact with HClO4in absence and presence of KCl, respectively.
After this characterization, EIS and MIC measurements are carried out. All our results are discussed qualitatively based on the relaxation of the double layer capacitance as a function of chloride ion concentration on the electrode solution interface.
REFERENCES:
[1] F.C. Anson, Acc. Chem. Res. 8 (1975) 400.
[2] D.C. Grahame, Chem. Rev. 41 (1947) 441.
[3] J. Lipkowski, W. Schmickler, D.M. Kolb, R. Parsons, J. Electroanal. Chem. 452 399, (1998) 193.
[4] T. Pajkossy, D.M. Kolb, Electrochim. Acta 54 (2009) 3594.
[5] E.R. Larios-Durán, R. Antaño-López, M. Keddam, Y. Meas, H. Takenouti, V. Vivier. Electrochim. Acta 55, (2010) 6292.
Modified Electrodes with Adsorbed Porphine Complexes on Modified Covalent Surfaces. Effect of the Covalent Bond on the Electrocatalytic Activity
Authors: Ramirez Galo , Canales Camila 
Published: February 2020

In this work, glassy carbon (GC) electrodes were modified with different species covalently bonded to the surface, being allowed to act as bridge molecules, for the posterior modification by adsorption of the azamacrocyclic complexes of transition metals. The bridge molecules that were studied were isonicotinic acid (GC-AL), 4-aminobenzoic acid (GC-PABA), 4-aminopyridin (GC-4AP) and the glassy carbon own functional groups obtained from its oxidation (GC-Ox). The modification was done through different methods that included the controlled-potential electrolysis in presence of the species, and electrochemical in-situ generation of the specie that was able for bonding.
Once this procedure was probed versus the redox couple Fe(CN)6
3-/ Fe(CN)6
2-, its electrocatalytic activity was studied versus oxygen reduction. It was found that the more active system, in comparison to the bare GC electrode, was the one that was obtained with the own GC functional groups (GC-Ox) (Figure 1A). Then, after the electrode was modified, the physical adsorption of the octaethyl porphine of M(II) complex (Figure 1B) was done, where M=Co, Cu, Zn, Ru and Fe. The modification process with the porphine was done by adsorption of monomer multilayers and by reflux, in order to obtain ordered systems with directional complex columns due to the different bridge molecules, as said before. It was found that the activity versus oxygen electroreduction was notoriously increased when the Co(II) complex is used, which shows a potential shift and a current increment. The figure 1C shows this behavior for the system modified with GC-Ox, as a covalent electrode. In this case, the Fe complex gets a better response in terms of current, but the potential shift is better accomplished with the Co(II) complex (GC-Ox-Co).

Acknowledgements: To Fondecyt project Nº 1120049
Preparation and Characterization Nanocomposites Based on Conducting Polymers and Functionalized Carbon Nanotubes with Different Dopants
Authors: Branzoi Florina , Branzoi Viorel , Pahom Zoia 
Published: February 2020

Conducting polymers can be doped and dedoped rapidly to high charge density and as a result are potential active materials for use in various electrochemical applications. Thus an important application is the fabrication of modified electrodes. For this reason, the nanocomposite materials based on the functionalized carbon nanotubes, conducing polymers and different anionic dopants (sodium dodecyl sulphate -SDS, sodium dodecylbenzenesulfonate - SDBS) were grown electrochemically onto a platinum substrate from an aqueous solution of 0.1M LiClO4, functionalized carbon nanotubes, surfactants and the corresponding monomer (3,4 ethylen-dioxythiophene). All the obtained composites showed improved mechanical integrity, higher electronic and ionic conductivity and exhibited larger electrode specific capacitance than the polymer alone. The negatively charged FCNTs served as anionic dopant during the electropolymerization to synthesize PEDOT/FCNTs composite films. The synthetic, morphological and electrochemical properties of nanocomposite materials type PEDOT / FCNTs / surfactants were compared. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry and scanning electron microscopy (SEM) were used to investigate the electrochemical properties of the composite films.
The specific electrochemical capacitance of the composite films is a significantly greater value than that for pure polymer films prepared similarly. Using these composite films, the modified electrodes with improved properties were obtained.
Lithium Based Ionogel as Solid State Electrolyte: Dynamics of Confined Ionic Liquid, a Neutron Diffusion Study
Authors: Cerclier Carole , Zanotti Jean-Marc , Embs Jan , Le Bideau Jean 
Published: February 2020

Ionic liquids (ILs) have been the focus of a rapidly growing number of studies in materials science since early 2000’s. Their liquid state is advantageous for their properties but often prevents their applications in devices which most often need solid state shaping. Thus, several approaches to get round this drawback are under investigation. Polymerizing the IL, grafting any of its ions onto a substrate, making physical gels … We have focused our work on confining IL in host matrices, resulting in solid materials, as well as leaving the dynamics features of the liquid state. The host matrix can be either fully inorganic, mixed polymeric and inorganic or fully polymeric. In each case, there is a continuous silica-to-IL interface, where silica has been obtained through sol-gel route. The solid obtained is thus endowed with properties of the choosen IL simultaneously with those of a robust host backbone including a silica interface.
The resulting ionogels, fully inorganic, mixed polymeric and inorganic or fully polymeric, are showing striking properties. The synergetic associations allow most often to lower the melting point of IL as well as to increase the ionic transport. It will be shown that the continuous interface and the confinement at nanoscale are modifying advantageously intensive properties of ILs. The conclusions are supported by results of studies with local probes (NMR, QENS, relaxometry, PGSE) and macroscopic measurements (CIS, BDS, DSC, IR) which show complementary information on chemistry, texture and physics (charge transport, dynamics, transmittance, dielectric …).
Among several potential applications, we are focusing on supercaps, lithium batteries, electrochromic and photochromic devices. The macroscopic observation of the properties of these solid devices shows either equal or superior properties as referred to genuine ILs.