bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detailed H2 and CO Electrochemistry for a MEA Model Fueled by Syngas
Authors: Lee Won Yong , Ong Katherine M , Ghoniem Ahmed F 
Published: February 2020

SOFCs are capable of directly oxidizing CO in addition to H2, which allows them to be coupled to a gasifier that converts coal, biomass or other carbonaceous fuels to synthesis gas. Most membrane-electrode-assembly (MEA) models neglect CO electrochemistry because H2 oxidizes more readily and most CO presumably shifts to H2 by the water-gas-shift reaction in the presence of H2O. In this paper we examine this assumption, especially at conditions of high current density and high CO-content syngas. The comprehensive 1D-MEA model presented here incorporates detailed mechanisms for both H2 and CO oxidation. The rate parameters and rate-limiting steps for the H2 mechanism are selected by fitting the model to experimental porous anode data for H2/H2O mixtures. The kinetic parameters of the CO mechanism were determined by matching the data to EIS measurements. The anode’s physical parameters, triple-phase-boundary length and nickel pattern width, are then determined by fitting the CO mechanism to porous anode data for CO/CO2 mixtures. The resulting H2 and CO mechanisms are then combined, along with surface reforming kinetics, into a single model that iterates through anode activation overpotential to resolve the individual current contributions of each fuel. We find that the model under-predicts experimental data for H2/CO mixtures when CO electrochemistry is neglected, but fits the data well at high current densities when CO oxidation is included. Furthermore, the combined model fits H2/CO data best when a single charge-transfer step in the H2 mechanism is assumed to be rate-limiting over the full range of current densities. This single rate-limiting step assumption for H2/CO mixtures differs from a previous finding that the H2 adsorption step becomes rate-limiting at high current densities for H2/H2O mixtures. This implies that adding CO to the fuel stream can fundamentally alter the H2 oxidation process. The individual H2 and CO current contributions for CO-rich syngas confirm that the addition of CO oxidation can delay H2 current saturation at high anode activation overpotentials, hence improving cell performance. These results indicate that CO oxidation cannot be neglected in MEA models running on CO-rich synthesis gas, and further studies are needed on the combined CO and H2 mechanism on Ni-YSZ.
Fuel Flexible and Efficient Semionics Single Layer Fuel Cell
Authors: Raza Rizwan 
Published: February 2020

Fuel cells are traditionally based on a three-layer configuration - anode, electrolyte and cathode –leading to a complex structure, not least since the three layers have to be chemically stable and mutually compatible. Our new electrolyte-free, single layer fuel cell represents a radically new approach to fuel cell research and design.
An advanced fuel flexible single layer/electrolyte free fuel cell with a functional nanocomposite was developed. Several different types of fuel, for example, gaseous (hydrogen and biogas) and liquid fuels (bio-ethanol and bio-methanol), were used in the experiments. Maximum power densities of 800, 300, 500, 400 mW cm-2 were achieved using hydrogen, bio-gas, bio-methanol, and bio-ethanol, respectively. These results show that single layer/electrolyte free fuel cell systems with functional nanocomposite offer significant advantages in reducing the operational and capital costs for the production of power and heat with a multi-fuel flexibility.
This system might be the one of the promising solutions for sustainable energy development. This study is based on nanocomposites for advanced fuel cell technology (NANOCOFC) to develop functional nanocomposite materials for next generation marketable products.

References

B.Zhu, Rizwan Raza, Q.Liu, H.Qin, L.Fan, “Fuel cells based on the electrolyte and non-electrolyte separator”
Energy and Environmental Sciences
, 2011, 4 (8), 2986 - 2992.
Production and Performance of Copper-based Anode-supported SOFCs
Authors: Azzolini Andrea , Sglavo Vincenzo Maria , Downs J A 
Published: February 2020

The production of tubular SOFCs supported by a cermet anode formulated with copper was successfully achieved. The optimization and the experience developed in the process of extrusion allowed to produce the composite anodes quickly and with good reliability. The low melting temperature of copper and its two oxides imposed a limit on the maximum temperature reachable during co-sintering of the cell. The study of the effect of different sintering aids on the densification of the GDC10 permitted to select Li2O as the most effective, being able to enhance the sinterability of the material and to decrease of more than 600°C its sintering temperature. Although its effect was remarkable, the densification of the thin electrolytic layer when bonded to the supporting anode could not be accomplished without analyzing and solving the issues related to its constrained sintering. A complete cell with a 10 um perfectly dense and crack free Li2O-GDC10 electrolyte, Li2O-GDC10:Cu2O 75:25 vol% anode and GDC10:LSF20 50:50 vol% cathode was obtained after one step sintering for 3h at 1020°C in argon atmosphere. The co-sintering permitted perfect adhesion of the three layers and no sign of debonding. One of the main fabrication problems related to the employment of Cu2O in the cermet anode was its low coefficient of thermal expansion that caused the onset of tensile stress in the electrolyte during cooling and the opening of brittle fractures on its surface. When the Cu2O was increased to 35vol% to insure the electrical conductivity of the anode, the sintering temperature had to be decreased to 995°C to minimize the cracks formation, although this affected the densification of the electrolyte layer. Cells formulated with Cu2O suffered from incomplete densification, cracks and oxidation of the cuprite during reduction. These issues made impossible to perform electrochemical tests.
Employment of CuO was less problematic, thanks to its resistance to oxidation and its higher CET. SOFCs were fabricated with Li2O-GDC10 electrolyte, Li2O-GDC10:CuO 60:40 vol% anode and GDC10:LSF20 50:50 vol% cathode. Sintering at 1020°C resulted in a fully dense electrolyte with a fine grain structure, although some cracks due to differential shrinkage could not be completely avoided. Despite this, the cell had a maximum OCV of 0.54 V and the highest measured power density was 8.98 mW cm-2 with a peak power density projected to be 27.5 mW cm-2 when tested at 600°C in dry H2. More test at lower temperatures are currently in progress.
These results do show that SOFCs can be produced with a copper cermet anode using similar methods used with NiO-based anodes by a one-step firing procedure at relatively low temperatures, thus having cost and high energy savings. The use of copper can allow for the use of light hydrocarbons in the cell without external reforming equipment or need of high steam to carbon ratio, and without the risk of carbon deposition in the cell
Performance of SOFC Power Unit Assisted by Paper-Structured Catalyst
Authors: Shiratori Yusuke , Sakamoto Mio , Tran Quang Tuyen , Uchiyama Yasuyuki , Uchiyama Naoki 
Published: February 2020

This study aims at the performance enhancement of direct internal reforming (DIR)-SOFC. Paper-structured catalyst (PSC) is a flexible catalyst material composed of inorganic fiber network loaded with metal catalyst which can be applied into cell stack to assist hydrocarbon reforming. Catalytic performance of PSC was considerably improved by the dispersion of Mg/Al hydrotalcite (HDT) in the inorganic fiber network to have higher tolerance to fuel impurity (sulfur) poisoning because of the formation of fine Ni particles and suppression of Ni loading on the inorganic fiber (SiO2-Al2O3) to cause coking.
High temperature SOFCs can convert chemical energy of a fuel directly to electricity even in the feed of low calorie gas. The use of engine-exhaust, which is most accessible lean gas, as a fuel for SOFC is promising idea. Recently, a compact SOFC unit operated by the direct feed of engine-exhaust was developed by Atsumitec Co., Ltd. However, performance of the DIR-SOFC unit can easily deteriorate, unless fuel is homogeneously supplied into the unit in which several numbers of stacks were arrayed. This study demonstrated that insertion of the HDT-dispersed PSC into the real SOFC stack between the cells led to 36 % increase in the performance because PSCs can boost up the output power of stacks placed at the positions where fuel is not well supplied.
Development of Medium-Temperature Solid Oxide Fuel Cells and CO2 and H2O Co-Electrolysis Cells in Estonia
Authors: Lust Enn , Tamm Kadi , Nurk Gunnar , Möller P , Kivi Indrek , Kanarbik Rait , Heinsaar Alar 
Published: February 2020

Various micro/mesoporous activated complex oxides as cathodes or andodes, bilayered Ce0.9Gd0.1O2-d|Zr0.92Y0.08O2-d electrolyte and various Ni-cermet and Ni-free anodes or cathodes have been designed and tested for high power density solid oxide fuel cells (1.5...1.6 W/cm2 (1073 K) and solid oxide electrolyzers. FIB-TOF-SIMS, FIB-SEM-EDX, HTXRD, BET, AFM and electrochemical impedance methods have been applied for analysis of the materials and completed single cells. Influence of porosity distribution (BET and 3D FIB-SEM data), cell potential and fuel composition on power density and fuel conversion efficiency has been demonstrated.
Acid-Base Membranes Based on Poly(1-vinylimidazole) for Fuel Cell Applications
Authors: Stewart Kerrilee Ayel , Missan Harinder Pal Singh 
Published: February 2020

Novel acid-base electrolyte membranes have been developed using the acid-base blending of a basic polymer poly(1-vinylimidazole) (PVIm) and an acidic polymer poly(ethylene-co-acrylic acid) (PEAA). High non-aqueous ionic conductivities of the order of 10-2 – 10-3 S/cm were observed for acid-base blend electrolytes over the temperature range of 30-120 oC and are found to be stable over the temperature range measured. The highest ionic conductivity was observed for 2-8 composition and was postulated to be due to better interaction between the acid and base sites along with better morphology. The blend electrolytes developed are found to be stable up to temperatures in excess of 450oC, even reaching 500 oC for 5-5 compositions. Nano-composite acid-base blend membranes using the 2-8 composition were then developed with the subsequent addition of nano-tubular titania into the electrolyte matrix. The ionic conductivity has been found to be effected by the addition of nano-tubular phase and is higher than that obtained for the parent electrolyte. This increase in conductivity is attributed to the better morphology of the electrolytes with the addition of nano-tubular titania into the matrix as inferred from SEM studies. Nanocomposite membranes were also found to be more thermally stable than the parent membranes. The addition of acid-functionalized nanotubular titania was found to further increase the ionic conductivity of the acid- base blend membranes whilst maintaining good thermal stability.
The Rate Limiting Step (RLS) for the Oxygen Reduction Reaction at the Cathode of Polymer Electrolyte Membrane Fuel Cell
Authors: Reda Mahmoud R. 
Published: February 2020

Proton exchange membrane fuel cells (PEMFCs) can be operated by hydrogen and pure oxygen (not air) by in-situ photo-catalytic splitting of water (gasoline of the future). Recently, several auto makers have introduced H2-fed fuel cell vehicles on the road. However, some concerns, i.e., catalyst and membrane’s cost and durability, catalyst activity, membrane proton conductivity, and water management, still exist. In order to make the fuel cell vehicle affordable and durable, further work needs to be done to improve each of the above mentioned aspects [1]. In a recent review by Ramaswamy and Mukerjee [2] have shown that the mechanism proposed by Damjanovic et al. describes the rate RLS. The purpose of this publication is to show that the rate limiting step for the ORR at the cathode of PEMFC is the rate of dissolution of gases oxygen in the aqueous media. It is well known that the Henry constant for oxygen in aqueous solutions is very low at range of temperature between 60 to 80 ̊ C (figure 1). The second purpose is to derive an equation that shows the strong relationship between the mass transfer coefficient and oxygen solubility. Strong supports for such a mechanism are:
1-In 2010 Erlebacher and co-workers [3] discovered a new ionic liquid that has strong affinity to absorb oxygen and were used to improve the rate of ORR. 2- The enhancement of the rate of ORR after humidification of the cathodic region (humid air contains dissolved oxygen) while humidification of the anodic region (can humidify the membrane and increase its conductivity) has no effect on the rate of ORR [4-6]
1-Perry M.L. and Fuller T.F., Journal of the Electrochemical Society 149, S59 (2002)
2-Ramaswamy N., and Mukerjee S. Fundamental Advances in Physical Chemistry Article ID 491604, (2012).
3-Snyder et al. Nature Materials 9, 904, (2010).
4-Ciureanu M. J. Applied Electrochemistry 34,705–714 (2004).
5-Xu H., Song Y., Kunz H.R., and Fenton J.M. , 205th meeting of the Electrochemical Society, San Antonio, Texas, (2004).
6-Zhang J., Tang Y., Song C., et al. Electrochimica Acta 53, 5315–5321 (2008).
7- Jeon D.H., Kim K.N., Baek S.M.,Nam J.H. In. J.of Hydrogen Energy, 36,19, 12499-12511 (2011).

Figure 1
Plasma-Coating of Ti and Ta on Graphite Composite As Corrosion-Improved Bipolar Plate in PEM Electrolysis
Authors: Sievers Gustav Wilhelm , Dempwolf Christoph , Hickmann Thorsten , Brüser Volker 
Published: February 2020

In Proton Exchange Membrane (PEM) Electrolysis bipolar plates have to be more corrosion resistant than bipolar plates in PEM Fuel Cells. Several materials have been evaluated as cost-efficient material in PEM Electrolyzers. Since the electrochemical conditions in PEM Electrolyzers are quite harsh, cost-efficient materials like stainless steel or graphite composites are not stable. Coating the material with corrosion resistant material by magnetron sputtering is one possibility to enhance the stability. Gago et al.[1] have been coating stainless steel for example with Ti by vacuum plasma spraying. However, Ti is only useable if the oxidation potential is not too high, otherwise it will form an insulating TiO2 layer. Tantal has good corrosion protective characteristics and is not forming an insulating layer.[2]
We developed a plasma process to deposit protective coatings on graphite composite bipolar plates. Therefore we used unbalanced magnetron sputtering of Ti and Ta. A new magnetron sputtering process was applied to keep the temperature of the graphite composites constant. Furthermore a combined plasma-process was used to enhance the stability of the deposited layer by activating the graphite composite. The Ti and Ta coatings were tested in a heated (T = 353 K) electrochemical cell amperometric at 2 V vs. RHE and by cyclic voltammetry in oxygen saturated 0.5 M H2SO4. We figured out the layer quality with the 4-Point Probe before and after each experiment. Furthermore we evaluated the film characteristics by microscope (SEM, light microscope), XRD and XPS.
We could demonstrate that the coating is protecting the graphite composite as bipolar plate material in harsh electrochemical environment which was choosen close to real conditions in PEM Electrolyzers. Thereby it should be possible to lower the cost of bipolar plates in PEM electrolyzers substantial.
[1] A. Gago, A. Ansar, N. Wagner, J. Arnold, K.A. Friedrich, Titanium coatings thermal spraying bipolar plates PEM electrolyzer, in: 64th Annu. Meet. Int. Soc. Electrochem., 2013.
[2] O.E. Kongstein, N. Guillet, A. Ødegård, Rapport technique DEHT-DR-10/051, 2010.
Kinetics of the Bromine Reaction at Carbon-Polymer Composite Electrodes in the Presence of Complexing Agents
Authors: Berlouis Leonard , Bryans Declan , Spicer Mark , Reglinski John 
Published: February 2020

The zinc-bromine hybrid redox flow battery (RFB) is one of the few battery systems that have seen implementation for the medium to large scale energy storage. One of the issues identified with this flow battery is that of bromine crossover from the positive electrode to the zinc electrode, leading to loss of current efficiency. One of the ways in which this problem can be overcome is through the use of organic-based complexing agents which tie up the bromine as a thin surface layer and an immiscible liquid phase which is pumped from the electrode surface into an external reservoir. In this paper, we examine in detail the kinetics and chemistry of formation of these complexed bromine ion pairs and establish the concentrations of the various complexing agents required to achieve full complexation of the electrogenerated bromine species. The initial phases of the study used small chain (2,3 and 4-carbon) symmetrical tetraalkylammonium bromide salts to investigate the bromide oxidation and the stages of film formation on a variety of carbon-composite electrodes commonly employed in RFB systems. These data were then compared to the classical responses obtained on Pt and glassy carbon electrodes. What is clearly evident from the study is that the electrochemical reversibly of the Br-/Br2
reaction is attenuated on the carbon-composite surfaces in the presence of the complexing agents and leads to a second oxidation process at more positive potentials (Figure 1). The nature of this second oxidation and of the surface species formed is investigated using in-situ Raman spectroscopy and its electrochemical characteristics examined using electrochemical impedance spectroscopy and potentiodynamic polarisation techniques. Substantial changes in the electrochemical responses are recorded when film formation occurs and this event also led to a large increase in the measured impedance, requiring the use of an additional low frequency time constant element in the Randles equivalent circuit employed to fit the impedance spectrum acquired. The magnitudes and trends observed in the impedance parameters at the different concentration and complexing species employed will be discussed in the presentation. Since in an operational Zn-Br2 RFB system during charge, the oxidation reaction will be occurring on composite carbon surface covered with the Brx
- complex, how this film impacts on the kinetics of the charge and discharge reaction will impact on the voltage efficiency. The understanding of the behaviour of these simpler complexing agents will thus enable the electrochemistry of more complex species, e.g. 1-methyl-1-ethylpyrrolidinium bromide, to be better understood and so lead to improvements in the efficiency of the process occurring at the positive electrode of the zinc-bromine hybrid RFB.

Figure 1
Oxygen Reduction Catalysis on Model Pt Electrodes
Authors: Bandarenka Aliaksandr S 
Published: February 2020

The use of model electrodes, particularly single crystals, represents a unique opportunity to better understand the performance of real-world (nanostructured) materials: identify active sites, elucidate factors responsible for selectivity and stability of the catalytic centers.
This approach is of growing importance for the electrocatalysis of the oxygen reduction reaction (ORR), which is nowadays one of the key reactions for both fundamental science and various technological applications. The latter include promising automotive applications or larger scale industrial processes, where it is involved in modern schemes of electrolytic production of chlorine (so-called oxygen depolarized cathode technology). From the point of view of fundamental science, the ORR has become an important model process which is critical for better understanding of reactions at electrified solid / liquid interfaces.
The common way of improving the activity of Pt towards ORR and many other reactions is a modification of the electronic properties of the surface through alloying it with other (mostly transition) metals. One can distinguish approaches which are based on “bulk”, “sub-surface” and “surface” alloying. Additionally, introduction of specific (often quasi-periodic) defects can also result in a drastic increase in the ORR activity. In the presentation, examples will be given of how the above-mentioned approaches can be used to design active surfaces; and how the model electrodes can help in better understanding of the performance of electrocatalytic systems.
Introducing Dichromate (Cr2O7
2-), an Oxidant with 100x the Current Density of O2 at 1/70th Its Solubility, and Other High-Power Oxidants for Redox Flow Batteries and Fuel Cells
Authors: Finkelstein David A. , Kirtland Joseph D. , Da Mota Nicolas , Stroock Abraham D. , Abruña Héctor D. 
Published: February 2020

While electrochemical fuels sample the range of the elements, from BH4
– to NH3 and Li to Zn, exploration of oxidants usually starts and ends with O2, a low-power oxidant with solubility <1 mM. In the studies presented, oxidants with solubilities up to 7,000 mM are characterized and demonstrated to produce current densities 100 times greater than O2 at just 100 mM. Alternative oxidants used in redox flow batteries (VO2
+, Ce4+) and fuel cells (H2O2, MnO4
–) are compared against the unorthodox oxidants ClO–, S2O8
2–, IO3
–, CrO4
2–, and Cr2O7
2–. It is shown that Cr2O7
2– produces among the highest current densities of all oxidants studied, at a diverse array of catalyst materials, and does so without the familiar drawbacks of precipitation and bubble-producing decomposition of MnO4
– and H2O2, respectively. Cr2O7
2–'s high n (number of e– transferred per molecule), D (diffusion coefficient) and C
max (maximum concentration) offer a route to achieving order-of-magnitude increases in the current and power densities of redox flow batteries currently using VO2
+ or Ce4+, which have low values for all three parameters.
Synthesis and Characterisation of Pd-Ni-Sn Electrocatalyst for Use in Direct Ethanol Fuel Cells
Authors: Jongsomjit Sompoch , Prapainainar Paweena , Sombatmankhong Korakot 
Published: February 2020

One critical challenge to commercialise direct ethanol fuel cells (DEFCs) is catalyst poisoning
associated with the strongly adsorbed CO intermediate on catalyst’s surface at low temperature. The present work
therefore aimed to develop a highly electrochemically active catalyst which is durable to the presence of CO
contaminant. Different Pd-Ni-Sn compositions impregnated on carbon black were synthesised by sodium borohydride
reduction method which can be classified as mono-, binary- and ternary-catalyst systems at which 20%w Pd/C was
utilised as a base catalyst. The addition of 5-20%w Ni and/or 5-20%w Sn metals was found to increase catalytic
activity and catalyst stability for ethanol oxidation reaction (EOR). Several diagnostic techniques were employed to
assess their suitability for use in DEFCs including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS),
transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive spectrometry (SEM-EDX)
and electrochemical techniques. The XRD and XPS spectra verified that the existence of Pd, Ni and Sn in the asprepared
catalysts was in the oxidation state of Pd0 and Pd2+, Ni2+ (in form of Ni(OH)2) and Sn4+ (in form of SnO2),
respectively, which were known to promote the EOR and CO oxidation. The average particle size was in the range of
5.46-10.56 nm for all samples. By using SEM-EDX, it was found that the actual ratios of metal loadings were relatively
similar to the desired compositions and their surface morphology was uniformly distributed. Moreover, electrocatalytic
activity towards EOR was evaluated using cyclic voltammetry in 1M ethanol (in 1M KOH). Among various catalytic
compositions, 20%w Pd/C containing 10%w Ni and 10%w Sn exhibited excellent catalytic activity and CO tolerance as
the maximum current density of 146 mA cm-2 for EOR and the highest electrochemical surface area were obtained
while lowering the CO-stripping peak potential to -0.525 V (vs Ag/AgCl).