bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of PEFC Membrane Electrode Assemblies for Iron-Doped Metal Organic Framework Catalysts
Authors: Uddin Md. Aman , Langhorst Lisa , Guo Yuqi , Zhang Hanguang , Chen Mengjie , Cullen David A. , More Karren L. , Xu Hui , Wu Gang , Litster Shawn 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) have been identified as one of the most promising technologies for future electric vehicles by using clean H2 with much improved energy conversion efficiency, long range, and rapid refueling. However, due to the large amount of platinum group metal (PGM) catalyst used in their electrodes, their prohibitively high cost hinders broad commercialization of PEFCs for transportation. Therefore, there is a critical need to develop low cost, high-performance PGM-free cathode catalysts that have the potential to dramatically transform the economics of PEFC commercialization by reducing catalyst costs by one to two orders of magnitude. However, before PGM-free cathodes become viable, several technical challenges associated with PGM-free cathodes must be addressed, including insufficient activity and stability of the catalysts, and serious water flooding and large transport losses in the electrodes.
Overcoming those barriers and ultimately meeting the challenging automotive PEFC performance targets requires comprehensive research and development effort on new PGM-free cathodes. In this work, we use a newly developed approach to synthesize PGM-free catalysts for Fe-doped metal-organic framework (MOF) precursors that yield atomically-dispersed FeN4-type active sites. These catalysts exhibit high activity and improved stability at typical fuel cell operating voltages. This presentation will focus on the development of membrane electrode assemblies with cathodes prepared from this catalyst. Specific areas that will be covered are water management in thick PGM-free cathodes, ionomer integration, and cathode fabrication. The implementation of these new materials and electrode designs is supported by a suite of advanced experimental and simulation tools that identify performance and durability bottlenecks, devise solutions, and establish rational material design and future synthesis targets.
This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Fuel Cell Technologies Office (FCTO) under Award Number DE-EE0008076. The authors gratefully acknowledge research support from the Electrocatalysis Consortium (ElectroCat), established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, under Contract Number DE-EE0008076.
Adsorption Behavior of PGM-Free Catalysts By Near-Ambient Pressure X-Ray Photoelectron Spectroscopy
Authors: Dzara Michael , Artyushkova Kateryna , Shulda Sarah M , Ngo Chilan , Crumlin Ethan J , Gennett Thomas , Pylypenko Svitlana 
Published: February 2020

Polymer Electrolyte Membrane Fuel Cells (PEMFCs) are an important component in the portfolio of renewable energy technologies that are important for our society. While being green technology, PEMFCs rely on precious metals to catalyze the oxygen reduction reaction (ORR) on the cathode side. Several approaches have been explored in order to reduce the amount of precious metals, including core-shell structures, extended thin films, and various alloys with non-precious metals. Potential solutions also include PGM-free catalysts made with earth abundant, inexpensive elements. One promising area of PGM-free catalyst development is the integration of nitrogen and iron into high surface area carbon nanostructures.1,2 These materials have significantly improved in activities over the past decade, yet their heterogeneous nature motivates further study into the nature of the active sites, with the goal of improving activity, active site density, and stability.
Multi-technique, multi-scale characterization of these materials, under ex situ and in situ conditions, provides opportunity to better understand surfaces of the materials under relevant conditions and to optimize various interfaces in these systems for optimum performance. In this work near-ambient pressure x-ray photoelectron spectroscopy (nAP-XPS) is used to investigate adsorption and desorption behavior of a diverse set of catalysts and supports, which contain nitrogen and iron sites of interest. Challenges associated with analysis of nAP-XPS data from adsorption and desorption studies include: i) presence of different types of potential sites and the multitude of binding energy shifts that could be happening upon adsorption on these various sites, ii) subtle changes in the spectra associated with adsorption/desorption due to low number of potential sites for adsorption, and iii) sampling depth limitations of the technique.3 To overcome these challenges, we explore less conventional approaches to analysis of the XPS N 1s and O 1s spectra, and complemented XPS with other in situ techniques such as diffuse reflectance infrared fourier transform spectroscopy (DRIFTS).
Figure 1. XPS N1s difference spectra comparing adsorption and desorption processes on a PGM-free FeNC material.

Jaouen, F., Proietti, E., Lefèvre, M., Chenitz, R., Dodelet, J.P., Wu, G., Chung, H.T., Johnston, C.M., and Zelenay, P., Energy Environ. Sci.
4, 114 (2011).

Wood, K. N., O’Hayre, R., and Pylypenko, S. Energy Environ. Sci.
7, 1212 (2014).

Matanovic, I., Artyushkova, K.; Strand, M. B., Dzara, M. J., Pylypenko, S., Atanassov, P., Core Level Shifts of Hydrogenated Pyridinic and Pyrrolic Nitrogen in the Nitrogen-Containing Graphene-Based Electrocatalysts: In-Plane vs Edge Defects. J. Phys. Chem. C
120, 51 (2016)

Figure 1
(Invited) Medium Temperature Fuel Cells: Stack and Material Advances
Authors: De Castro Emory Sayre , Pavlicek Ryan , Sharma Manav , Kanellopoulos Thomas , Zelenay Piotr , Yin Xi 
Published: February 2020

Fuel cells that operate between approximately 150 oC and 250 oC accrue certain advantages, most notably facilitated operation with low grade / low cost hydrogen sourced from carbon feedstocks, direct oxidation of high energy density fuels such as dimethyl ether, robust cathode performance in the presence of air contaminants, absence of balance of plant components for stack water management, high quality heat, and readily sourced materials of construction. Fuel cells running at these intermediate temperatures with phosphoric acid as the electrolyte currently hold the record for a commercial lifetime warrantee (1). Yet, lower temperature polymer electrolyte fuel cells (PEFC) operating at under 100 oC and comprised of a conductive membrane, electrodes, and gas diffusion layers offer the potential for low cost assembly at high volumes, especially if these components are made with roll-to-roll processes. The better of these two technologies would be a hybrid high temperature Membrane Electrode Assembly (MEA) based on phosphoric acid electrolyte.
Advent Technologies identified and developed a pyridine polymer based TPS® system using phosphoric acid imbibed into the membrane matrix. Advent’s TPS membranes operate over a wide temperature range from ~120 °C to greater than 200 °C. In 2014, Advent became the licensee of BASF’s PBI MEA (P1100W) and gas diffusion electrode technology. Advent develops, manufactures, and markets both PBI and TPS MEAs. Thus, these two platforms fulfill the promise of the operating features of the phosphoric acid electrolyte with the manufacturing ease of MEAs.
This presentation will present an overview and survey of advances pertaining to medium temperature fuel cells. The survey will include examples of membrane developments including next generation PBI as well as TPS MEAs operating at over 200 °C with direct fuels. We will present several commercial successes utilizing the features of medium temperature fuel cells. Lastly, we will show the results of Advent’s efforts in leveraging our HT MEAs in medium temperature stack technology in the 100W to 3kW range.
1. http://www.doosanfuelcell.com/en/main.do
Impact of Gas Diffusion Layer Mechanics on PEM Fuel Cell Performance
Authors: Irmscher Philipp , Qiu Diankai , Janßen Holger , Lehnert Werner , Stolten Detlef 
Published: February 2020

In a stack assembly cells are clamped together and therefore mechanical interactions are induced into the stack. The mechanical behaviour has a strong influence on the performance. For example the gas diffusion layer (GDL) is a porous layer which will lose its porosity if the pressure level is too high, whereas the contact area between GDL and flow field needs high pressure for a low contact resistance [1].
In this study experiments are performed to investigate the mechanical behavior of different GDL materials in a Polymer Electrolyte Membrane (PEM) Fuel Cell. The relationship between pressure on the active area and the performance of a single cell is determined. For this purpose, a test cell from Baltic Fuel Cells GmbH, Germany, is used, which allows to change the pressure level during fuel cell operation and to record performance curves. Thus, the optimum operating point of the cell can be determined. To distinguish which mechanical effects have an influence, ohmic resistance [2] and permeability measurements depending on the mechanical load on the GDLs were performed. To analyze the mechanical structure scanning electron microscope (SEM) pictures were taken from the different GDLs.
The test results regarding the optimum pressure level show that the performance decreases strongly at pressures below 0.6 N/mm². This is explained by the increasing contact resistance between the individual components. At higher pressure levels the expected performance optimum is achieved for some GDL materials. The SEM pictures reveal that the fibres took mechanical damages starting from dents up to GDL areas with a high amount of broken fibres. But some materials show a different behaviour from that. For example a pressure level above 1 N/mm² results in a constant performance plateau, an increase of the pressure up to 3 N/mm² does not increase or decrease the performance anymore. The contact resistance is no longer noticeably reduced at these pressures, while even at the maximum pressure of 3 N/mm², enough gas passes through the porous GDL to the membrane, so the porosity is still sufficient.
These results show that the mechanical behavior influences the characteristics of the GDL and the performance of the fuel cell. A minimum pressure of 1 N/mm² on the entire active area should be ensured for the used GDL types for an optimum performance of a PEM fuel cell, whereas the maximum clamping pressure depends strongly on the type of GDL which is used.

D. Qiu, P. Yi, L. Peng, X. Lai; Assembly design of proton exchange membrane fuel cell stack with stamped metallic bipolar plates; International Journal of hydrogen energy 40 (2015) 11559-11568

D. Qiu, H. Janßen, L. Peng, P. Irmscher, X. Lai, W. Lehnert; Electrical resistance and microstructure of typical gas diffusion layers for the proton exchange membrane fuel cell under compression; (2018) submitted
(Invited) Further Excursions into the Probing of Internal and Interfacial Structure of Ionomer Thin Films
Authors: Karan Kunal 
Published: February 2020

The critical importance of catalyst layer ionomer in numerous transport phenomena (proton conduction, oxygen and water transport) and also in catalyst utilization at multiple length scales is well acknowledged [1]. Thickness-dependent properties such as proton conductivity, water uptake, swelling and water diffusivity have now confirmed that ionomer thin films possess properties significantly different than those of the bulk ionomer materials [2]. Previous work from our group, both independent and collaborative, confirmed suppression of proton conductivity in thin films [3], wettability changes with film thickness and thermal annealing [4], influence of substrate on internal structure [5] and water uptake [6], similarity of T2-relaxations in proton NMR of thin and thick films [7] and recent discovery of temperature-dependent vibrational mode of Nafion ionomer [8].
Tremendous progress made on the topic of ionomer thin films over the past decade has been summarily presented in a recent review [2]. However, many aspects of ionomer thin film structure and properties still remain unknown. For example, despite the confirmation of strong thickness-dependence of ionomer properties for film below 50 nm thickness, one question continues to elude us: what is the critical thickness below which ionic domains cannot be sustained? In a quest to answer this question, we have employed high-resolution electron microscopy to deduce the presence/absence of ionic domains in 4-30nm thin films. There is indication of a critical thickness below which domains are evidently not present.
Recent neutron reflectometry measurements from our group have focussed on the quantification of interfacial water (Pt/ionomer interface) and water in the bulk phase of the ionomer thin films on platinum substrate. The results acquired to date indicate that both interfacial and bulk water are dependent on the ionomer molecular structure. Complementing these measurements with GISAXS, ellipsometry, QCM and impedance spectroscopy – a clearer picture of the ionomer structure-property is emerging.
The talk will share these new results and discuss the implications of the findings on fuel cell behaviour.
Reference:

Karan, Current Opin. Electrochem. 5 (1), (2017) 27-35.

Kusoglu, A.Z. Weber Chem Rev, 117 (3) (2017), 987-1104

K. Paul, R. McCreery, K. Karan, J Electrochem Soc, 161 (14) (2014), F1395-F1402

K. Paul, H.K.K. Shim, J.B. Giorgi, K. Karan, J Polym Sci Part B: Polym Phys, 54 (13) (2016), 1267-1277

Kusoglu, D. Kushner, D.K. Paul, K. Karan, M.A. Hickner, A.Z. Weber, Adv Funct Mater, 24 (2014), 4763-4774

K. Shim, D.K. Paul, K. Karan, Macromolecules, 48 (22) (2015), 8394-8397

NE De Almeida, DK Paul, K Karan, GR Goward, J Phys Chem C 119 (3), (2015) 1280-1285

VO Kollath, K Karan, Physical Chemistry Chemical Physics 18 (37), (2016) 26144-26150
Polymer Electrolyte Fuel Cell Degradation through Foreign Cation Contamination, Proton Depletion and Carbon Corrosion
Authors: Banas Charles Joseph , Arman Md. Tanvir Alam , Uddin Md Aman , Park Jaehyung , Bonville Leonard J. , Pasaogullari Ugur 
Published: February 2020

Foreign cation contamination causes accelerated degradation in polymer electrolyte fuel cells (PEFCs). Because foreign cations have a higher affinity to the sulfonic acid side chains, they replace protons in perfluorosulfonic acid (PFSA) membranes, reducing ionic conductivity and lowering water content, leading to reduced oxygen reduction reaction kinetics.1-2

While foreign cations are known to cause several degradation mechanisms in PEFCs, no study has examined the influence of cationic contamination on carbon corrosion. In this work, we report on the results from 400 hour fuel cell tests were performed on commercial, as-received and Ca2+ contaminated catalyst coated membranes (CCMs) to evaluate the effects of long term exposure of foreign cations on fuel cell performance and degradation. Following testing, significant thinning of the cathode catalyst layer was observed across the entire active area in the contaminated cell, while only localized thinning was observed in the as-received baseline CCM.
Analysis of the elemental maps and line intensity profiles of platinum (Pt) obtained from energy dispersive X-ray spectrum (EDX) shows minimal change in total platinum content across the thickness of the catalyst layer, and hence loss of carbon is suspected to be the cause of the thinning. A numerical model2 is employed to show the foreign cation redistribution during testing, which shows proton depletion in the cathode catalyst layer when the CCM is contaminated with foreign cations (shown in Figure 1). We hypothesize that this lack of protons leads to accelerated carbon corrosion in the cathode to supply protons to oxygen reduction where foreign cations block transport of protons. A carbon corrosion scheme is presented which shows that under the operating potentials of the cell, carbon oxidation can occur, leading to the observed thinning.
References
1) T. Okada et al., J. Phys. Chem. B, 103, 3315-3322 (1999).
2) M.A. Uddin and U. Pasaogullari, J. Electrochem. Soc.
161(10), F1081-F1088 (2014).

Figure 1
Phosphonated Ionomers for Ion-Pair Coordinated High Temperature Pemfcs
Authors: Lee Albert S , Park Eun Joo , Atanasov Vladimir Milanov , Kerres Jochen , Jia Hongfei , Kim Yu Seung 
Published: February 2020

High temperature proton exchange membrane fuel cells (HT-PEMFCs) offer significant advantages over PEMFCs operating below 100 °C including the lack of need for humidifiers and smaller radiator sizes due to simplified thermal management, potentially providing a solution to vastly reduce the cost of fuel cells and their application to automobiles.1 Polymer electrolytes based on phosphoric acid-doped polybenzimidazole have given decent fuel cell performance, but suffer from stability issues stemming from the leaching of the liquid phosphoric acid carrier electrolyte at either lower temperatures or when exposed to water.2 While our previous development of ion-pair coordinated electrolyte systems improved the versatility of fuel cell operation temperature,3 this study investigates the optimization of HT-PEMFC performance through various electrodes formulation with a phosphonated ionomer based on a pentafluorostyrene,4 mitigating the need for electrode post-doping procedures. In this presentation, we report the benefits of using phosphonated ionomers for ion-pair coordinated membrane fuel cells under anhydrous conditions.
References

Chandan, M. Hattenburger, A. El-kharouf, S. Du, A. Dhir, V. Self, B.G. Pollet, A. Ingram, W. Buljaski, J. Power Sources, 2013, 231, 264-278.

Li, J.O. Jensen, R.F. Savinell, N.J. Bjerrum, Prog. Polym. Sci., 2009, 34, 449-477.

-S. Lee, J.S. Spendelow, Y.K. Choe, C. Fujimoto, Y. S. Kim, Nature Energy, 2016, 1, 16120-16124.

Atanasov, A. Oleynikov, J. Xia, S. Lyonnard, J. Kerres, J. Power Sources, 2017, 343, 364-372.
Shape-Controlled Pt Nanoparticles for the Electro-Reduction of Oxygen
Authors: Safo Isaac Adjei , Oezaslan Mehtap 
Published: February 2020

Undoubtedly, shape-controlled Pt nanoparticles are of great interest in today´s fuel cell research, because they build a unique bridge between UHV-prepared single crystals and industry-related catalysts. Since most of the fundamental studies for the oxygen reduction reaction have been performed by using single crystals, the knowledge transfer to real nanoparticle catalyst system is heavily limited.[1-3] However, surfactants and capping agents are required to control the growth, orientation and size of the seeds to form nano-scaled single crystals with high mono-dispersity. Therefore, simple strategies to clean the superficial surfaces of the single nanocrystals without any structural and electro-catalytic losses are needed.
In this work, we investigated shape-controlled Pt nanoparticles like nanocubes for the ORR by using various synthetic routes. We revealed that the electronic structure of these shape-controlled Pt nanoparticles is modified in dependence on the kind of surfactant or capping agent used in the preparation. To understand the interaction between surfactant and metallic surface, which strongly affect the number of catalytically active centers and thus the catalytic ORR activity, we used a combination of different techniques like high resolution (scanning) transmission electron microscopy (HR-(S)TEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR). In addition, we provide cleaning procedures to successfully remove the surfactant without any particle shape loss. For instance, a combination of solvent washing and electrochemical cleaning increase the electrochemically surface area of the Pt nanocubes by a factor of 10 – 15. This immeasurably boosts the catalytic properties of the Pt nanocubes for the ORR. Nevertheless, after successful cleaning process the structural stability and electrochemical durability of the “naked” Pt single-nanocrystals were investigated by applying accelerated degradation protocols. A structural transformation of the single nano-crystals to near-spherical nanoparticles was identified to be dependent on the electrochemical potential and the number of scans. Our goal is to better understand the interplay between surfactant-metal interaction and electrochemical reaction process for the development of highly active nano-crystal surfaces and to fill the knowledge gap between single crystal surfaces and nano-scaled polycrystalline materials for the ORR.

Reference

[1] M. Oezaslan, F. Hasché, P. Strasser, The Journal of Physical Chemistry Letters, 4 (2013) 3273-3291.
[2] D. Li, C. Wang, D.S. Strmcnik, D.V. Tripkovic, X. Sun, Y. Kang, M. Chi, J.D. Snyder, D. van der Vliet, Y. Tsai, V.R. Stamenkovic, S. Sun, N.M. Markovic, Energy & Environmental Science, 7 (2014) 4061-4069.
[3] I. A. Safo, M. Oezaslan, Electrochemical acta, 241 (2017) 544 - 552
In Operando Characterization of Cutting Edge Fuel Cells Catalysts Using X-Ray Absorption Spectroscopy: Capabilities of the XAFS Beamline at Synchrotron Elettra (Trieste, Italy)
Authors: Pollastri Simone , Aquilanti Giuliana , Fiala Roman , Olivi Luca , Mysliveček Josef , Matolin Vladimir 
Published: February 2020

In a world with a growing population, the demand for energy is rising as never before and we are aware that fossil fuels are not the solution due to their enormous environmental costs (such as the effects of climate change) that can only be thwarted in a low-carbon society.
In this context, the role of batteries and fuel cells in everyday life is undeniable, and tremendous efforts are made to optimize their performances. The knowledge of the relationship between the electrochemical processes and the chemical and morphological changes is a necessary step for such optimization.
An inevitable ingredient of this research are the experiments conducted in operando conditions, very useful for the study of the local chemical environment of electrode materials (electrodes, electrolytes and catalysts). In fact, in operando experiments, the collected data provide an accurate representation of the reaction behavior found under normal operating conditions and with realistic gaseous or liquid environments. Moreover, experiments conducted with this method allow to prevent several drawbacks due to the sample transfer needed for typical ex situ measurements. Alteration of air or moisture sensitive species is avoided, as well as the occurrence of relaxation reactions which might show up when the electrical circuit is open, inducing a transformation of the initial cycled material. The whole study can be performed on a single test cell suppressing the effects of uncontrolled differences in a set of cells which are needed for a stepwise ex situ study of the electrochemical mechanism.
X-ray absorption spectroscopy is a synchrotron radiation based technique that is able to provide information on both local structure and electronic properties in a chemically selective manner. It can be used to characterize the dynamic processes that govern the electrochemical reactions, and to shed light on the redox chemistry and changes in structure to design efficient materials with improved properties. The XAFS beamline at Elettra is dedicated to X-ray absorption spectroscopy and can operate in a large energy range (from 2.4 to 25 keV). Although conceived to be general purpose, recently a lot of research has concerned the operando study of state of the art fuel cells and batteries.
In this presentation, the XAFS beamline at synchrotron Elettra will be described together with the experiments conducted in operando conditions on proton-exchange membrane fuel cells (PEMFCs) in the context of the CERIC Grant Research proposal “CEROP”, aimed at deciphering single-atom catalysis in Pt/ceria systems. Moreover, improvements recently implemented at the XAFS beamline to perform this type of measurements will be shown.