bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poly(2,6-dimethyl-1,4-phenylene oxide) Based Anion Exchange Membranes for Fuel Cell Applications
Authors: Sarode Himanshu N , Kuo Mei-Chen , Ferrari Paolo , Herring Andrew M 
Published: February 2020

Anion exchange membranes are an integral part of a low temperature polymer electrolyte fuel cell. They serve the purpose of transporting hydroxide ions from cathode to anode while acting as a separator for fuel and air.
In this work we are focused on synthesis and device testing of some novel poly(2,6-dimethyl-1,4-phenylene oxide) based AEMs. The idea is to start with a polymer that is readily available in the market and synthesize large quantities of functionalized materials. Our work centers around attaching conventional quaternary ammonium cations as well as long spacer chain quaternary ammonium cations on the polymer backbone. We solvent cast and melt press the synthesized polymer to fabricate a membrane. Melt pressing crosslinks the membrane and adds the required mechanical and dimensional stability. We are able to achieve high degree of chlorination (~80%) of polyphenyle oxide and still maintain the swelling properties of the polymer because of crosslinking.
Our initial experiments show that the membrane has promising chloride conductivity, mechanical and dimensional stability thus making it suitable for fuel cell testing. We are also testing the device performance of these membranes using H2/O2fuel cell with Pt/C catalyst at various temperatures and different humidification levels to find the optimum operating conditions without causing significant degradation of the membrane.
Overall we are reporting a novel AEM material with simple chemistry which can be synthesized in large batches with ease and can serve as s good fuel cell membrane in the future.
Evaluating Electrospun Polyacrylic Acid-Nafion Composite As Stable Catalyst Support for PEM Fuel Cell Electrodes
Authors: Kayarkatte Manoj Krishna , Delikaya Öznur , Roth Christina 
Published: February 2020

Production of energy through renewable and sustainable processes are important goals for the future in the context of depleting fossil fuels and environmental pollution. In this regard fuel cell technology offers an attractive combination of highly efficient fuel utilization and environmentally friendly operation. For successful commercialization of low temperature proton exchange membrane (PEM) fuel cells, they should have a long life and a high performance.
Recently, high performance fuel cell electrodes were obtained by electrospinning a solution containing proton conducting Nafion and commercial platinum catalyst powder along with PAA as electrospinning polymer. Electrospinning of the catalyst together with Nafion ionomer resulted in enhanced triple phase boundaries which resulted in high fuel cell performance. Moreover, it was also found that the stability of the electrodes is significantly higher than the electrodes prepared from the same catalyst by conventional methods. However, carbon corrosion still ensued.
In this work, we demonstrate the stability of polyacrylic acid (PAA) - Nafion composite as a stable support due to which the Pt after the carbon corrosion does not come out of the system. On the contrary, it stays entrapped in the membrane electrode assembly giving significance performance even after the corrosion protocols/measurements. Here, we first produce Pt nanoparticles that are produced by a photochemical reaction of the precursor induced by UV light. To this, PAA and Nafion (1:2 by weight) were added and stirred overnight. The resulting solution was electrospun. (Small amount of carbon was added in some cases to get the desired conductivity) to get a Pt/PAA-Nafion catalyst as shown in transmission electron micrograph. The electrodes are first tested for electrochemical stability by potential cycling and then in the fuel cell test bench using the FCCJ recommended cell evaluation protocol.

Figure 1
Performance Evaluation on Hydrocarbon Polymer Electrolytes for PEFC Cathode
Authors: Matsuura Toyoaki , Ogu Kenichi , Rikukawa Masahiro 
Published: February 2020

Cost reduction and performance improvements are still major issues for polymer electrolyte fuel cells (PEFCs). To solve these problems, the relationship between internal transport phenomena and performance in PEFCs are an essential factor.
Particularly, the mass transport phenomena in the catalyst layer comprehends several unclear parts, which is desired to clarify. Evaluation of membrane electrode assemblies (MEAs) with different kind of ionomer materials under operating conditions are effective to clarify the impact of ionomer proton conductivity and gas diffusivity in the performance. However, these experiments are difficult due to less variety of ionomer materials.
We have already introduced poly (p-phenylene) based diblock hydrocarbon polymers has comparable properties to perfluorinated polymer electrolytes. Moreover, these materials can be used as model materials because their compositions and structures can easily be controlled. [1, 2] In this study, we synthesized several hydrocarbon polymer electrolytes for cathode ionomer, and the effect on the fuel cell performance was investigated.
The catalyst coated membranes (CCMs) were prepared for this study. Fig.1 shows the structure of hydrocarbon polymer electrolyte which was utilized for the cathode ionomer. It was synthesized by catalyst transfer polycondensation of the hydrophobic and hydrophilic monomers. The synthesized polymer electrolyte was dissolved in tetrahydrofuran (THF). Platinum supported on carbon black (Pt/C) catalyst (TEC10E50E, Tanaka Kikinzoku) and pure water were added to the solution, and the solution was mixed by a bead mill (BSG02, AIMEX). Nafion was utilized for the anode ionomer. Pt/C, isopropyl alcohol, and water were added to the Nafion solution (D2020, DuPont), and mixed by a bead mill. These catalyst inks were applied to polymer electrolyte membranes (NRE211, DuPont) by a pulse spray system (V5R02, Nordson).
A prepared CCM was installed in a single cell with two gas diffusion layers (SGL25BC, SGL). The single cell consists of separators with flow channels (1mm depth, 1mm width and 1mm rib), current correctors, and end-plates.
Electrochemical impedance spectroscopy (EIS) was performed by a potentio/galvanostat (HZ-7000, Hokutodenko). The cell temperature was remained at 80ºC, and 0.5 L/min hydrogen and 1.0L/min nitrogen were fed into the single cell. Both gases were humidified at 100%RH.
The cathode proton conductivity of the CCM with the hydrocarbon ionomer was close value of the CCM with Nafion ionomer. This result shows the hydrocarbon ionomer work well under practical operating conditions.
Details of their electrochemical activities and performance evaluation results are presented at the symposium.
Reference
[1] Umezawa, K., Oshima, T., Yoshizawa-Fujita, M., Takeoka, Y., & Rikukawa, M. (2012). ACS Macro Letters, 1 (8), 969-972.
[2] Takeoka, Y., Umezawa, K., Oshima, T., Yoshida, M., Yoshizawa-Fujita, M., & Rikukawa, M. (2014). Polymer Chemistry, 5 (13), 4132-4140.

Figure 1
Correlation Between Metal-Support Interaction and the Stability of Platinum Nanoparticles Supported on Heteroatom Doped Mesoporous Carbons for Oxygen Reduction Reaction
Authors: Kim Jae Hyung , Kim Jong Hoon , Park Jeong Young , Joo Sang Hoon 
Published: February 2020

Polymer electrolyte membrane fuel cells (PEMFCs) have been regarded as a key element for the development of sustainable and renewable energy conversion devices, owing to their high efficiency and environmental benignity. In PEMFCs, carbon supported Pt-based catalysts (Pt/C) have shown the best activity, yet they are easily deteriorated via several degradation processes such as Pt particle detachment, Pt dissolution, and/or Ostwald ripening. Therefore, understanding and enhancing the durability of Pt catalysts is one of the major challenges for long-term operation of PEMFC. To improve the stability of Pt/C catalysts, recently, heteroatom-doped carbons have been exploited as support materials. In this work, we investigated the relationship between metal-support interaction and durability of Pt catalysts for the oxygen reduction reaction (ORR). For this purpose, three different types of heteroatom-doped ordered mesoporous carbon (OMC) supports, namely O-doped OMC (O-OMC), N,O-doped OMC (N,O-OMC), and S,O-doped OMC (S,O-OMC), were prepared and Pt nanoparticles were supported on these carbon supports. The interaction between Pt and doped OMC supports was investigated by using atomic force microscopy (AFM). It was revealed that the S,O-OMC exhibited the strongest adhesion with Pt, whereas the N,O-OMC showed the weakest adhesion. X-ray diffraction patterns and X-ray photoelectron spectroscopy corroborated the adhesion results. In accelerated degradation tests for the ORR, Pt/S,O-OMC exhibited the highest durability, followed by Pt/O-OMC and Pt/N,O-OMC. These results suggest that sulfur has the strong adhesive strength with Pt, thereby enhancing the durability, but nitrogen exert less adhesive force with Pt, undermining the durability.
NiMo As Non-Precious Metal Catalyst for Hydrogen Oxdiation Reaction in Alkaline Media
Authors: Kwon YongKeun , Kim MinJoong , Cho EunAe 
Published: February 2020

Fuel cell is environment-friendly power source which has high efficiency in generating electricity. Polymer electrolyte fuel cell uses hydrogen as a fuel that only produces water as byproduct which does not cause any pollution. Currently, commercialized Nafion-based polymer electrolyte membrane fuel cell (PEMFC) applied Pt/C as both cathode and anode catalyst which cause cost inefficiency in manufacturing fuel cell stack.
Anion exchange membrane fuel cell (AEMFC) is being developed to combine advantages of both PEMFC and traditional alkaline fuel cell (AFC). By adopting solid membrane as electrolyte, leakage problem and insoluble salt precipitation could be solved. Furthermore, alkaline condition enhances oxygen reduction reaction (ORR) kinetics which obstructs cell power in PEMFC. However, stability of membrane is still in issue, and hydrogen oxidation reaction (HOR) kinetics are significantly diminished [1], which leads to higher Pt loading. This research is focusing at slow HOR kinetics and reducing catalyst cost by replacing Pt into non-precious metals such as transition metals.
One of the well-known HOR catalyst for alkaline fuel cell is nickel. Several studies show nickel has catalytic activity of hydrogen oxidation in alkaline media [2,3], but it’s not enough to overcome precious metals such as platinum. Therefore, diverse researches tried to enhance activity of nickel by expanding surface area or doping other elements [4]. However, these catalytic activities were only tested in 6 M KOH, 60~80 ℃ condition, which is identical to real cell operating condition.
NiMo catalyst was synthesized by electrodeposition method which is cost-effective way to produce. Nickel chloride is used for nickel source, and sodium molybdate worked as molybdenum source. Galvanostatic electrodeposition was applied to synthesize NiMo catalyst. Rotating disk electrode (RDE) was used to remove evolved hydrogen efficiently.
HOR activity was measured in hydrogen saturated 0.1 M KOH solution. RDE was used to control diffusion with 1600 rpm speed. Experiment was held at room temperature. To remove capacitive current, steady state polarization method was applied for measuring HOR activity.
Figure 1 shows HOR current of commercial Pt/C, electrodepositied NiMo, Ni. Adding small amount of Mo in Ni increases HOR current significantly. At overpotential of 20 mVRHE, Pt/C shows current density of 1.12 mA/cm2, where NiMo has 0.86 mA/cm2which is about 77% of Pt/C HOR activity.
Reference
[1] W. Sheng, et al., J. Electrochem. Soc. 157 (11), B1529 (2010)
[2] T. Tomida, et al., J. Electrochem. Soc. 136 (11), 3296 (1989)
[3] H. K. Lee, et al., Mat. Chem. Phys., 55, 89 (1998)
[4] J. A. Linnekoski, J. Fuel Cell Sci. Tech., 4, 45 (2007)

Figure 1
Characterizing the Pt-Electrolyte Interface in PEM Fuel Cells
Authors: Garrick Taylor Reed , Moylan Thomas E , Yarlagadda Venkata , Kongkanand Anusorn 
Published: February 2020

Much progress in reducing the platinum loading in proton exchange membrane (PEM) fuel cell cathodes to a target of 0.1 mg-Pt/cm2 has been made. However, large performance losses are observed at high current densities at low cathode platinum loadings. Recent studies have shown that the large losses are caused due to resistances at or near the catalyst-ionomer interface.[1] This resistance can be countered through the use of ionomers designed to interact with Pt in a way that does not limit the oxygen reduction reaction. However, the development of tools to quantify and characterize this resistance is needed to enhance our understanding of this resistance and correlate it with performance loss.
In the early 1990’s Feliu et al. developed a method for measuring adsorbed ion charges on Pt single crystals in an aqueous electrolyte.[1] We have validated this CO displacement method on polycrystalline Pt and carbon-supported Pt nanoparticles in an aqueous electrolyte and present here results from implementing this methodology in a fuel cell. Figure 1 illustrates the current transient measured during chronoamperometry as CO gas is introduced to the cathode of a fuel cell. The measured displacement charge at potentials less than 0.2 V represent a displacement of adsorbed protons, corresponding to a positive displacement current. At potentials greater than 0.3 V, a negative current is measured corresponding to the displacement of negatively charged adsorbed species. In the case of a fuel cell cathode, these negative species are the sulfonate group present in the ionomer. The adsorption charge can then be integrated to determine the amount of species adsorbed on the surface at each potential. Using this tool, ionomer adsorption for different ionomer types at different operating conditions can be examined.
[1] Kongkanand A, Mathias MF, J. Phys. Chem. Let. 7 (2016) 1127.
[2] Feliu JM, Orts JM, Gomez R, Aldaz A, Clavilier J. J. Electroanal. Chem. 372 (1994) 265.
Figure 1. Chronoamperometry at different potentials during CO Displacement. Introduction of CO to the cathode occurs at t=120s.

Figure 1
Diagnostic Analysis of the Oxygen Fraction at the Boundary Between Cathode Flowfield and Gas Diffusion Layer in the PEMFC
Authors: Hirano Shinichi , Chen Jixin , Shimpalee Sirivatch , Wang Chunmei , Saloka George 
Published: February 2020

Enhancement of the fuel cell performance at higher current densities is important to improve the power density and reduce the cost of proton exchange membrane fuel cell (PEMFC) system. Mass transport overpotential is the major barrier to achieving high performance at high current density. The overpotential at the cathode is significantly large and the oxygen partial pressure in the oxygen reduction reaction (ORR) area is vital. Condensed water in the flowfield and the gas diffusion layer (GDL) reduces oxygen transport to the ORR area. Direct investigation of oxygen transport has been limited by an inability to resolve water saturation dependent properties. A novel diagnostic method to analyze the boundary between flowfield and GDL surface is required. A measurement of the oxygen partial pressure in the flowfield while the fuel cell is operating was introduced [1-3]. This method uses oxygen sensitive fluorophore materials whose fluorescent luminescence is a function of oxygen quenching as described by the Stern-Volmer equation. In the previous work, the oxygen quenching rate was modified in order to enable in-situ oxygen partial pressure measurement on the surface of the cathode GDL with typical operating conditions of an automotive PEMFC [3]. In this work, a computational fluid dynamic (CFD) based two-phase fuel cell model was newly developed to be validated with measured oxygen fractions. Figure 1 shows the geometric configuration of this tested single cell. Figure 2 shows that simulation of oxygen partial pressure distribution shows similarity to the previous experimental data. Figure 3 shows measured oxygen partial pressure on the cathode GDL surface along with fraction of flowfield channel length. This oxygen fraction is deviated from the average stoichiometric line. The spatial variability of current density, which is proportion to the oxygen consumption rate, is considered to be a large contributor. Combined empirical and modeling approaches enable to gain the mechanistic understanding of two-phase fluid flow in the flowfield and the surface of GDL, including water condensation and implication with the fuel cell operating conditions. Further analysis will be discussed.

References:

J. Inukai, et. al, Angewandte Chemie International Edition, 47(15):2792-2795

S. Hirano, et. al, ECS Trans. 58 (1) 1791-1797 (2013)

S. Hirano, et. al, ECS Trans. 2015 69(17): 1331-1339 (2015)

Figure 1
Impact of Polymer Electrolyte Membrane Properties on Transport, Performance and Durability
Authors: Dutta Monica , Ghassemzadeh Lida , Young Alan P , Lauritzen Michael Victor , Knights Shanna 
Published: February 2020

The structure and properties of the polymer electrolyte membrane has a major impact on the MEA performance and durability. Polymers with different chemical structures can propose different mechanisms for water and proton transport which lead to differences in performance and durability. For membranes with similar chemical structures, factors such as thickness and equivalent weight (EW) are crucial in transport and therefore could cause differences in the performance. The focus of this work was a closer look at the impact of these properties, and their changes due to degradation, on the performance and durability of the MEA and its components.
The impact of membrane thickness and equivalent weight was studied by comparing the water content of different PFSA membranes as a function of relative humidity (RH). The data was then used to further discuss the conductivity and hydrogen permeability of the membranes in different regimes of temperature and RH. The impact of membrane chemical degradation on transport property was studied by comparing the membrane conductivity, thickness, hydrogen permeability and performance before and after membrane degradation. To study the impact of membrane properties on cathode catalyst performance and degradation, the cathode degradation test was applied on MEAs with and without membrane degradation, and the results were compared.
The water content (Lambda) of all membranes showed a type II isotherm increase by increasing the relative humidity. Lambda was found to be independent of membrane thickness and equivalent weight, while, as expected, the absolute water content (g water/g membrane) showed a decrease at higher equivalent weights. Increasing the relative humidity and operational temperature showed an increase in membrane conductivity. Higher thickness or higher equivalent weight both resulted in higher membrane resistance; supporting a more general trend which is the linear increase of membrane conductivity with increase in the absolute water content.
Cathode degradation testing showed an impact on the ECSA loss and performance. The effect was more intense for thinner or lower EW membranes suggesting that membrane water content was the contributing factor. After the membrane degradation test, losses in membrane thickness, membrane conductivity, performance and ECSA were observed. In addition, the hydrogen crossover increased due to the membrane thinning. The membranes with pre-existing degradation showed less ECSA loss but increased performance losses. This trend was explained by the combination of higher catalyst layer ionomer resistance and platinum depletion which lead to higher catalyst layer ionic losses related to a reaction distribution shift further into the catalyst layer.

Acknowledgements: Funding was provided by Department of Energy EERE Hydrogen and Fuel Cell Technology Program (Project DE-EE0006375).
(Invited) High Performance Fe/N/C-Based ORR Electrocatalyst and Its Application in Alkaline Fuel Cell
Authors: Zhou Zhi-You , Chen Chi , Rauf Muhammad , Yang Xiao-Dong , Wang Yu-Cheng , Sun Shi-Gang 
Published: February 2020

Fe/N/C is a promising electrocatalyst for oxygen reduction reaction (ORR). This type catalyst can perform in both acidic and alkaline media. In acidic media, the active sites of Fe/N/C can be corroded; however, in alkaline media, Fe/N/C can exhibit high stability. Therefore, it is promising to explore the applications of Fe/N/C catalyst in alkaline fuel cell. Herein, we will talk about our recent advances in preparation of Fe/N/C catalysts and the application of them in alkaline fuel cells: (1) By using 2-aminothiazole, a molecule containing both N and S atoms, we prepared S co-doped Fe/N/C catalyst with graphene nanosheets. In alkaline solution, this catalyst exhibited high ORR activity with half-wave potential of 0.926 V and mass activity of 0.56 A g-1 @ 1.0 V. Furthermore, the catalyst displayed excellent durability, and only lost 9% of initial activity after 100 h of durability test at 0.80 V. In alkaline anion exchange membrane fuel cell (AEMFC) test, the peak power density could reach 164 mW cm−2. (2) We used the unzipped carbon nanotubes as carbon support and melamine as nitrogen source, and prepared a Fe/N/C catalyst with high ORR activity in alkaline media. The edge sites of unzipped carbon nanotubes play a key role for high catalyst activity. (3) we explored a series of nitrogen source including binary polymer of melamine-terethalaldehyde, ternary polymer of cynuric acid, 2, 4-diamino-6-phenyl-1, 3, 5-triazine, and melamine. N-doped carbon nanotubes with encapsulated Fe nanoparticles were prepared. The catalyst exhibited considerably high ORR activity in alkaline solution. We further tested its performance in alkaline membrane direct ethanol fuel cell, and the peak power density was about 64 mW cm-2. These results demonstrated that Fe/N/C is a promising candidate for ORR electrocatalyst in alkaline fuel cell.

References

[1] C. Chen et al. Chem. Commun., 2015, 51, 17092-17095.
A Simple and Inexpensive Organometallic Compound Catalyzing Oxygen Reduction Reaction
Authors: Ramanujam Kothandaraman , Sheelam Anjaiah 
Published: February 2020

One of the major obstacles in fuel cell commercialization is the cost of the precious metal catalysts used for oxygen reduction reaction (ORR) and hydrogen oxidation reaction(1). Recently, non-precious metal catalysts are mainly obtained by the pyrolysis of the transition metal, carbon and nitrogen sources together and these catalysts are viewed as potential alternative to the expensive platinum based catalysts(2). Pyrolysis step leads to formation of several nitrogen and transition metal based functionalities covalently embedded on the carbon surface(3). Hence, identifying the exact chemical structure of the ORR active site in the pyrolyzed catalyst remains elusive. Hence, designing a synthesis process (which includes pyrolysis) with an objective of maximizing the number of active sites is a work in progress. To avoid difficulties associated with such process, we propose a metalorganic complex capable of catalyzing ORR. As it is a molecular material, its characterization by single crystal XRD, 1H and 13C NMR unambiguously predicted the structure. In this study we report ORR on bis(2,2’-bipyridine-N,N’)carbonatocobalt(III)nitrate pentahydrate. The above said complex was immobilized on the Ketjenblack carbon and its ORR activity was measured in O2 saturated 0.1 N KOH solution (Figure (a)). This complex crystalizes in monoclinic (C 2/c) crystal structure and its crystal structure is shown in Figure (b).

Figure Shows (a) the cyclic voltamograms recorded at different rotation rate in O2-saturated (solid lines) and in N2-saturated (dash line) 0.1 N KOH electrolyte and (b) crystal structure of the metalorganic complex employed in this work.

References:

1. Y. Wang, K. S. Chen, J. Mishler, S. C. Cho and X. C. Adroher, Appl. Energy, 88, 981 (2011).
2. X. Li, H.-J. Zhang, H. Li, B. Zhao and J. Yang, J. Electrochem. Soc., 161, F925 (2014).
3. K. Artyushkova, A. Serov, S. Rojas-Carbonell and P. Atanassov, J. Phys. Chem. C, 119, 25917 (2015).

Figure 1