bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Sulfonated Poly(Ether Ether Ketone) Pretreatments on Proton Exchange Membrane Fuel Cells Performances and Durability
Authors: Daoudi Meriem , Ferri Evelise , Tougne Claire , El Kaddouri Assma , Perrin Jean-Christophe , Dillet Jérôme , Salah Touhami , Mainka Julia , Gonon Laurent , Mareau Vincent H , Mendil-Jakani Hakima , Dufaud-Niccolai Véronique , Espuche Eliane , Gain Olivier , Lottin Olivier 
Published: July 2022

Many works have been devoted to the development of low cost ionomers as alternative to perfluorosulfonic acid membranes for Proton Exchange Membrane Fuel Cells (PEMFC) applications. Among them, sulfonated Poly(Ether Ether Ketone) (sPEEK) membranes. Before use, sPEEK membranes must be pretreated to ensure a complete protonic substitution and removal of residual reagents/solvent. This is generally ensured by soaking the membrane in an acid solution -at room temperature or higher, usually at 80°C1- followed by a rinsing step in water at room temperature. In addition to these pretreatment steps, it was reported2 that an hydrothermal treatment in water at high temperature for a few hours to a few days can improve the membrane nanostructure, water uptake and proton conductivity with expected positive effects on performances. Herein, we studied the impact of sPEEK membrane pretreatment on fuel cell performances and durability using two different batches of Fumapem E730 from Fumatech, acquired in 2019 and in 2020. Five different protocols were tested. The first consists only in membrane acidification and rinsing, while the four others also include a hydrothermal treatment in water at 80°C from 1 hour to 72 hours, and possibly an additional hydro alcoholic treatment. The 2020 batch membranes subjected to a hydro alcoholic pretreatment followed by a 72-hours hydrothermal pretreatment achieved the best performances and the lowest high frequency resistance (Rhf) when tested in a fuel cell. Their performances even exceeded those of a Nafion XL membrane. This could be explained by a better ionomer nano-structuration and therefore a better protonic conductivity. These performances are compared to those of the 2019 batch. In addition, the impact of pretreatment is investigated via Accelerated Stress Tests (AST) combining load (hence potential) and load-driven humidity cycling, and open-circuit voltage.
References:
(1) Jun, M.-S.; Choi, Y.-W.; Kim, J.-D.. J. Membr. Sci.
2012, 396, 32–37. https://doi.org/10.1016/j.memsci.2011.12.008.
(2) Mendil-Jakani, H.; Zamanillo López, I.; Mareau, V. H.; Gonon, L. Phys. Chem. Chem. Phys.
2017, 19 (24), 16013–16022.

Figure 1
Influence of Carbon Support Type, Presence of Platinum and Ionomer Content on Agglomeration in Catalyst Layers
Authors: Kariuki Nancy N. , Park Jaehyung , Lindell Matthew , Haug Andrew , Myers Deborah J. 
Published: July 2022

Polymer electrolyte fuel cell (PEFC) energy conversion systems have found application in transportation applications due to their high power density, low operating temperature, high energy conversion efficiency, and speed of refueling.1 One of the key components of a PEFC is the membrane electrode assembly (MEA), which consists of a proton exchange membrane (PEM), such as a perfluorosulfonic acid (PFSA), sandwiched between two catalyst layers (CLs) serving as anode and cathode. Several studies of CL microstructure−performance relationships suggest that the electrode microstructure characteristics, such as the extent of the catalyst−ionomer interaction, continuity of the ionomer phase, and pore size distribution are critical for performance.2-4 However, successful implementation of novel materials for PEFC electrodes is hindered by the lack of a fundamental understanding of the complex, multicomponent nature of the CL, the interplay of its components, and their independent and cooperative effects on the effective properties and performance.
In this work, ultra-small angle X-ray scattering (USAXS) was employed to investigate the effects of carbon support type, presence of platinum, and ionomer loading on catalyst agglomeration in CLs. Particle size distributions (PSDs), obtained from fitting the scattering data using the maximum entropy (MaxEnt) method, were used to determine the size of carbon aggregates and agglomerates from carbon-ionomer and platinum-carbon-ionomer CLs. Three types of carbon supports were chosen for the investigation: high surface area carbon (HSC), Vulcan XC-72, and graphitized Vulcan XC-72. CLs with a range of perfluorosulfonic acid (PFSA) ionomer loadings (0.2-1.0 ionomer to carbon ratio, I/C) were studied in order to evaluate the effect of ionomer on the CL agglomerate structure. The CL agglomerate structure will be correlated with electrochemical performance to reveal the interplay of the components, and their independent and cooperative effects on performance.

References

B.D. McNicol, D. A. J. Rand, K. R. Williams, J. Power Sources 100 (2001) 47–59.

F. C. Cetinbas, X. Wang, R. K. Ahluwalia, N. N. Kariuki, R. P. Winarski, Z. Yang, J. Sharman, and D. J. Myers, J. Electrochem. Soc., 164, (2017) F1596–F1607.

Y.-C. Park, H. Tokiwa, K. Kakinuma, M. Watanabe, M. Uchida, J. Power Sources 315 (2016) 179-191.

S. Holdcroft, Chem. Mater., 26 (2014) 381−393.

This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the auspices of the Fuel Cell Performance and Durability Consortium (FC-PAD). The Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science User Facility. Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, also under contract DE-AC-02-06CH11357.
Fabrication and Performance Evaluation of Tubular Catalyst Layer for Proton Exchange Membrane Fuel Cell
Authors: Pedram Sara , Jankovic Jasna 
Published: July 2022

Over the past several decades, planar proton exchange membrane fuel cells (PEMFCs) received considerable attention due to their simple structure, manufacturing, and easy integration. However, current PEMFC electrode designs are disadvantaged by high cost, insufficient mass transport, nonuniform reactant, current and temperature distribution, and limited water removal. The development of a novel tubular fuel cell design could address these challenges. Tubular-shaped PEMFC offers several advantages over planar one, including lower pressure drop, efficient water removal, reduced mass transport losses, and cost reduction owing to removing one of gas diffusion layer/bipolar plate (GDL/BPP) side.
This work developed a carbon nanofiber (CNF)/Pt-based cathode for a tubular fuel cell. The tubular CNF support for Pt catalyst was fabricated employing the electrospinning method. Polyacrylonitrile (PAN) was used as the precursor. The electroless deposition of Pt using the chloroplatinic acid solutions was applied to produce well-dispersed low Pt loading nanowires. The tubular CNF/Pt electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), ex-situ cyclic voltammetry to determine the CF and Pt morphology and feasibility of the prepared layer in PEMFC application. SEM images indicated that increasing the Pt precursor concentration in the plating bath leads to higher Pt loading and larger Pt clusters on the CNF surface. The calculated electrochemical active surface area (ECSA) trend imparts that high Pt loading is less favorable as thick Pt layers lead to low Pt utilization and increased material costs. ECSA results agreed with SEM images, suggesting that the medium Pt concentration (1.5 g L-1 Pt precursor) developed a homogenous Pt distribution and comparable Pt surface area of 24 m2 gPt
-1 for the Pt loading of 0.046 mg cm-2, proving the feasibility of the proposed process.
Operating Proton Exchange Membrane Fuel Cells at a Constant Relative Humidity
Authors: Bielefeld Nikolaj M. , Sørensen Rasmus D. , Jørgensen Mikkel , Kure Kristoffer S. , Berning Torsten 
Published: July 2022

Proton exchange membrane fuel cells are currently being commercialized for numerous applications ranging from electric vehicles to stationary applications to miniature type of fuel applications. For the miniature fuel cells, it is desirable to operate at very high current densities in order to maximize the power density. Because at high current densities, the waste heat generation and removal becomes a substantial practical problem, gas diffusion layers (GDL) made out of perforated metals have recently become of interest. Here, a chemical etching process is applied to create uniform holes of equal size(around 80 microns) in a metal sheet. While this type of GDL has superior heat transfer properties and has been found to keep the fuel cell at an almost constant temperature, the uniformly sized holes must be kept from flooding. On the other hand, it is known that the fuel cell membrane must be kept hydrated in order to have a satisfactory proton conductivity.
The purpose of this work is to investigate the possibility of maintaining a relative humidity of 100 % across the entire length of the flow channel. This is to keep the membrane perfectly hydrated while at the same time preventing flooding. The height and width of the flow channels in these fuel cells are in the range of 200 microns, causing a high pressure drop, and as the pressure decreases along the flow channel, the relative humidity would decrease. However, the relative humidity can then be maintained by adding water as a result of the electro-chemical chemical reaction in the fuel cell. Thereby, conditions for which the relative humidity stays constant at 100% over the entire channel length can be calculated, assuming the current density is uniform and that for simplicity all the product water exits the cell at the cathode side.
In this work, a model will be constructed and solved in the Engineering Equation Solver (EES). The output of the model will be the required stoichiometric flow rate to maintain a constant relative humidity for different channel geometries, pressure gradients and temperatures.
Strain Evolution in Pt-Ni Alloy Nanoparticles during Electrochemical Ni Leaching Revealed By Bragg Coherent Diffraction Imaging
Authors: Kawaguchi Tomoya , Komanicky Vladimir , Latyshev Vitalii , Cha Wonsuk , Maxey Evan , Harder Ross , Ichitsubo Tetsu , You Hoydoo 
Published: July 2022

Alloy catalysts such as Pt-M (M: other metal elements) have been extensively developed to improve the sluggish oxygen reduction reaction (ORR) that limits the efficiencies of fuel cells and metal-air batteries. Their catalytic activity is potentially enhanced by strain induced in a nearly pure Pt "shell" formed by dissolving the alloyed metal (M) from the surface. It is, therefore, of great importance to reveal the strain distribution on the Pt shell in situ so that we can exploit this mechanism to design new alloy catalysts. Yet, it has been challenging to analyze the strain on the shell because it inevitably requires a technique that can image the strain field of the nanoparticles with high spatial resolution.
In this study,1 we successfully revealed the strain of the exemplary Pt-Ni alloy nanoparticles in detail from the 3D images obtained by using a novel synchrotron technique, “Bragg Coherent X-ray Diffraction Imaging” (BCDI), which can directly image minute atomic displacement field owing to the X-ray coherence. Pt-Ni nanoparticles with compositions of Pt2Ni3 (Ni rich), Pt1Ni1 (moderate Ni), and Pt3Ni2 (Ni poor) were observed by BCDI during cyclic voltammetry cycles, in which the less noble metal Ni electrochemically leached from the alloy. This cycling induced tensile strain inside particles in all the compositions, implying that the formation of a Pt shell on the surface strained the core of the particle because of the lattice mismatch between the Pt-Ni alloys and Pt. The strain in the shell was evaluated from a core-shell elastic model using the parameters obtained in the 3D images.
A compressive circumferential strain in the shell was observed in all the compositions, and the Pt1Ni1 particle showed the largest compressive circumferential strain of 5%. Since the compressive strain is reported to facilitate the enhanced ORR,2 the compositional dependence of the strain magnitude observed in this study was in excellent agreement with the previous study performed with nm-size particles where Pt1Ni1 exhibits the highest activity among a wide range of compositions.3
A similar strain-activity relation was also inferred in a powder X-ray diffraction studies of core-shell Pt
x
Co1-x
alloys,4 suggesting it is a widely applicable phenomenon. The present study demonstrated that the strain on alloy nanoparticles can be quantitatively determined by BCDI during electrochemical reactions, which enables us to exploit surface strain in designing a wide range of electrocatalysts.

T. Kawaguchi et al., Nano Letters, 21, 5945–5951 (2021).

H. Wang et al., Science, 354, 1031–1036 (2016).

C. Wang et al., Advanced Functional Materials, 21, 147–152 (2011).

D. Wang et al., Nature Materials, 12, 81–87 (2013).
Electrochemical Trends of Atomically Dispersed Metal-Nitrogen-Carbon Materials As Oxygen Reduction Reaction Catalysts and Active Supports
Authors: Ly Alvin , Wang Hanson , Murphy Eamonn , Huang Ying , Guo Shengyuan , Liu Yuanchao , Zenyuk Iryna V. , Atanassov Plamen 
Published: July 2022

Platinum-based catalysts currently remain the best option for polymer electrolyte membrane fuel cell (PEMFC) applications. Meanwhile, atomically dispersed metal-nitrogen-carbon (MNC) materials have been the frontrunner for platinum-group metal free catalysts for the oxygen reduction reaction (ORR)1. Considering that the platinum-based nanoparticles are preferably supported on carbonaceous materials, it would be intuitive to use MNC catalysts as a support for platinum nanoparticles to further increase the activity and performance of the catalyst layer in a PEMFC. In this work, we synthesized and investigated a series of MNC materials (Mn-N-C, Fe-N-C, Co-N-C, Ni-N-C, and Cu-N-C) using a previously described method2 to elucidate the electrochemical trends of possible interactions between the MNC materials as a support and standard Pt nanoparticles. Recent works3,4 have shown that combining MNC catalysts with Pt catalysts not only improves the activity of the overall composite catalyst, but also improves the stability of both counterparts. As shown in Figure 1, the supported Pt nanoparticles on MNC materials outperforms the same type of Pt nanoparticles when supported on an industry standard carbon.
Reference

Asset, T. & Atanassov, P. Iron-Nitrogen-Carbon Catalysts for Proton Exchange Membrane Fuel Cells. Joule
4, 33–44 (2020).

Murphy, E. et al. Using Atomically Dispersed Bimetallic Active Sites to Probe the Nitrate Reduction Mechanism to Ammonia. ECS Meet. Abstr.
MA2021-02, 1559 (2021).

Ao, X. et al. Atomically dispersed Fe–N–C decorated with Pt-alloy core–shell nanoparticles for improved activity and durability towards oxygen reduction. Energy Environ. Sci.
13, 3032–3040 (2020).

Qiao, Z. et al. Atomically dispersed single iron sites for promoting Pt and Pt3Co fuel cell catalysts: performance and durability improvements. Energy Environ. Sci. (2021).

Figure 1
Synthesis of Nitrogen-Doped Wood-Based Carbon Materials and Their Application for Oxygen Reduction
Authors: Tamasiunaite Loreta , Upskuviene Daina , Balciunaite Aldona , Jasulaitiene Vitalija , Niaura Gediminas , Drabavicius Audrius , Plavniece Ance , Volperts Aleksandrs , Dobele Galina , Zhurinsh Aivars , Norkus Eugenijus 
Published: July 2022

Recently, great attention has been focused on biomass-derived electrocatalysts for the oxygen reduction reaction (ORR). In the present study, the wood-derived nitrogen-doped carbon nanomaterials with graphene-like structures have been synthesized from wood biomass using a chemical activation method with NaOH to achieve a high specific surface area (SSA). Then, the activated carbon materials have been doped with nitrogen using dicyandiamide (DCDA) as a cheaper nitrogen precursor. The synthesized catalyst's morphology, structure, and composition have been characterized using TEM, XPS, Raman Spectroscopy, and ICP-OES. The activity of the prepared catalysts was evaluated for ORR in the 0.1 M KOH solution employing the rotating disk electrode (RDE) method. The nitrogen-doped carbon materials have been shown a high electrocatalytic activity and stability for the oxygen reduction reaction. The number of electrons transferred per O2 molecule is close to 4.0.
Acknowledgment
This project has received funding under the Baltic Research Programme project “Sustainably produced nanomaterials for energy applications (SuNaMa)” (No. S-BMT-21-12, LT08-2-LMT-K-01-055).
(Digital Presentation) Temperature-Dependent Study for Electrochemical Surface Area on a Catalyst Layer Used in a PEFC
Authors: Espinoza R. , Munoz Kevin , Santana Jordy , Espinoza Andaluz Mayken , Andersson Martin 
Published: July 2022

Electrochemical Surface Area (ECSA) is the portion of the catalyst layer electrochemically available to participate in electrode reactions inside a Polymer Electrolyte Fuel Cell (PEFC). ECSA is an important metric that diagnoses the performance/degradation of a catalytic layer and allows the development of new electrodes. This study aims to describe the behavior of the ECSA as a function of cell operating temperatures based on a self-designed experimental based on two approaches. The first is through an analytical-theoretical analysis, and the second is through empirical correlations that fit the experimental curves obtained. The primary variable to study in the present work is temperature. Based on previous studies, the temperature is one of the most influential variables that affect fuel cell efficiency.
A single PEFC with an active area of 25cm2, a woven carbon cloth gas diffusion layer, a microporous layer, catalytic layer support with 0.5 mg cm-2 of Platinum on carbon, and Nafion 212 ® membrane were used to perform this study. The temperature range was varied in the range of 40 - 80 oC in steps of 10 °C, and a 100% of Relative Humidity on inlet gases, i.e., hydrogen and nitrogen, were settled at 100%. The characterization of the ECSA was performed with an in-situ cyclic voltammetry test, and the voltage sweep was conducted from 0 to 0.8 V. Finally, the volumetric flow was fixed at 0.1 L/min for both gases hydrogen on the anode side and nitrogen on the cathode side. The results show that the electrochemical surface area (ECSA) of the cathode catalyst decreases drastically as the operating temperature of the cell increases; this is due to the decrease of active sites by the fewer hydrogen ion pathways reaching higher temperatures. Consequently, the empirical correlation proposed for the electrochemically active area in this study helps the catalyst layer's diagnosis and predicts the level of performance for different temperatures.

Figure 1
(Digital Presentation) Large–Scale High-Performance Low Catalyst Loaded Membrane Electrode Assemblies for Advanced Proton Exchange Membrane Water Electrolyzers
Authors: Zeng Zhiqiao , Bliznakov Stoyan , Bonville Leonard J. , Ouimet Ryan J. , Niedzwiecki Allison , Capuano Christopher , Ayers Katherine E. , Maric Radenka 
Published: July 2022

Hydrogen is regarded as the next-generation energy carriers for the future hydrogen economy.1 Among the hydrogen production technologies, proton exchange membrane (PEM) water electrolyzers is considered the favored approach for the implementation of the global hydrogen energy transformation due to its several benefits including high power density operation, low ohmic losses and differential pressure operation. However, (i) high cost mainly from the high platinum group metals (PGM) loading in the catalysts layers; (ii) low durability due to instability of the catalysts layers and membrane; and (iii) poor safety because of hydrogen crossover of PEM water electrolyzers have jeopardized their widespread commercialization. Currently, a new Department of Energy Consortium (H2NEW) has targeted hydrogen production from electrolysis, especially PEM water electrolysis, for use as a clean, sustainable fuel, which can achieve $2/kg hydrogen production cost by 2025.2 This requires a balance between the performance, durability and scale-up cost of membrane electrode assemblies (MEAs) for PEM water electrolyzers.
In this work, we demonstrate the capability to fabricate large scale MEAs by the unique Reactive Spray Deposition Technology (RSDT), that have one order of magnitude lower PGM loadings in the catalyst layer than the state-of-the-art (SOA) designs, and activity and durability performance comparable to the SOA commercial MEAs. RSDT is a flame-based method that combines the catalysts synthesis and electrodes deposition processes into one step and thus substantially reduces the time and cost for their fabrication.3–5 The RSDT fabricated MEA with 680 cm2 geometric area electrodes, and loadings of 0.2 mgPt/cm2 in the cathode and 0.3 mgIr/cm2 in the anode has been tested at current density of 1.8 A cm-2, 50 oC, and 400 psi differential hydrogen pressure. The initial steady-state test for over 250 hours, clearly shows excellent activity and stability. In addition, the RSDT fabricated MEA has integrated dual recombination layers that effectively reduce the hydrogen crossover to below 10 %LFL at all current densities from 0.58 to 1.8 A/cm2.
Reference
1. M. Carmo, D. L. Fritz, J. Mergel, and D. Stolten, Int. J. Hydrogen Energy, 38, 4901–4934 (2013).
2. https://www.energy.gov/sites/default/files/2021-09/h2-shot-summit-panel1-lte-status.pdf
3. H. Yu et al., Appl. Catal. B Environ., 239, 133–146 (2018) https://doi.org/10.1016/j.apcatb.2018.07.064.
4. H. Yu et al., Electrochim. Acta, 247, 1155–1168 (2017) http://dx.doi.org/10.1016/j.electacta.2017.07.093.
5. G. Mirshekari et al., Int. J. Hydrogen Energy, 46, 1526–1539 (2021) https://doi.org/10.1016/j.ijhydene.2020.10.112.