bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insight into the Chemical Stability of N-Heterocyclic Ammonium Groups for Anion-Exchange Polyelectrolytes
Authors: Jin Yiqi , Chen Nanjun , Li Hui , Liu Haijun , Fan Jiantao 
Published: February 2024

The chemical stability of cationic groups, not only related to alkaline degradation but also to electrochemical degradation at high potentials, is the key factor that limits the durability of anion exchange membranes (AEMs) and anion exchange ionomers (AEIs) [1]. In recent years, quaternary ammonium (QA) groups represented by N-heterocyclic ammonium (NHA) groups display excellent ionic conductivity and superior alkaline stability, which makes NHA groups promising candidates to be applied in AEMs and AEIs [2]. However, electrochemical degradation of NHA groups has been neglected in previous research, even though the electrochemical oxidation of phenyl QAs was found in the ionomer at the oxygen evolution potentials [3]. In short, the mechanism by which effect of substituents affects the durability of NHAs cations, including alkaline stability and electrochemical stability, is unclear yet, and NHA groups must be attached to the polymer backbones by substituents to achieve their applications.
In this work, the chemical stability of NHA is comprehensively studied. To investigate the relationship between alkaline durability and structure, we report a systematic study on the alkaline stability of 24 representative NHA groups at different hydration numbers (λ). The electronic effect of substituents on NHA groups and degradation mechanisms of NHA groups are systematically investigated by 1H nuclear magnetic resonance (1H NMR) and density functional theory (DFT) calculations, showing that the NHA groups with electron-donating substituents exhibit outstanding alkaline stability and linking NHA groups with the polymer backbone via γ-position could be a rational design for highly alkaline stable AEMs and AEIs. Furthermore, a constant voltage is applied to the QAs electrolyte solution to measure the electrochemical stability by simulating the real operating environment of and AEM water electrolyzers. Compared to structural changes before and after voltage application, NHA exhibits worse stability than alkyl QAs, involving the radical degradation and electrochemical degradation. These results above give us a clearer picture while designing the polymer used for electrochemical devices, which is that a careful balance needs to be established between alkaline and electrochemical durability, especially under the high potential and harsh alkaline environment.
References
[1] D. Li et al., “Durability of Anion Exchange Membrane Water Electrolyzers,” Energy Environ. Sci., vol. 14, no. 6, pp. 3393-3419, Jan. 2021.
[2] M. G. Marino et al., “Alkaline Stability of Quaternary Ammonium Cations for Alkaline Fuel Cell Membranes and Ionic Liquids,” ChemSusChem, vol. 8, no. 3, pp. 513-523, Feb. 2015.
[3] D. Li et al., “Phenyl Oxidation Impacts the Durability of Alkaline Membrane Water Electrolyzer,” ACS Appl. Mater. Interfaces, vol. 11, no. 10, pp. 9696-9701, Feb. 2019.

Figure 1
Nanostructured Fe-N-C Electrocatalysts with CeO2 Additives for PEM Fuel Cells
Authors: Kırlıoğlu Ahmet Can , Buldu-Akturk Merve , Rahbarshendi Faezeh , Yurum Alp , Alkan Gursel Selmiye , Yarar Kaplan Begum 
Published: February 2024

The development of cost-effective electrocatalysts for polymer electrolyte membrane fuel cells (PEM fuel cells) is essential for the widespread use of this technology. The high cost and limited availability of Pt-group metals (PGMs) used as catalyst materials are the main barriers to the widespread commercialization and development of PEM fuel cells. [1] Therefore, the use of high surface area and effective catalysts without Pt have gained great importance in PEM fuel cells. This study introduces high surface area electrocatalysts that are free of platinum group metals (non-PGM) consisting of iron-nitrogen-carbon (Fe-N-C). Here, the uniform distribution of Fe was achieved using graphene oxide (GO) nanoparticles to enhance the catalyst's performance for oxygen reduction reaction (ORR). [2] Furthermore, the addition of a small amount of cerium oxide (CeO2) nanoparticles to the catalyst layer helps to prevent the degradation of the catalyst and ionomer by preventing H2O2 formation as well as increasing the ORR activity due to high oxygen storage capacity. [3] Initially, GO is synthesized by improved Hummer’s method. The GO nanoparticles are obtained through a process involving ball-milling and acid treatment. These nanoparticles are then thermally reduced and nitrogen-doped to form nitrogen-doped reduced graphene oxide nanoparticles. Fe-N-C complexes are synthesized by reacting these nanoparticles with FeCl2 precursor, which are then hydrothermally treated to introduce CeO2 additives. The resulting catalysts are analyzed using various techniques (FT-IR, XPS, SEM, TEM, EDX) and display excellent electrochemical performance. The ORR activity of the Fe-N-C catalysts was investigated and compared with the electrocatalysts prepared with larger graphene oxide particles. A similar comparison is also made with and without CeO2 additives.
The authors gratefully acknowledge the financial support of The Scientific and Technological Research Council of Turkey (TÜBİTAK) (Grant Number: 122M429)

References

[1] He, C., Desai, S., Brown, G., & Bolleplli, S. (2005). PEM fuel cell catalysts: Cost, performance, and durability. The electrochemical society Interface, 14(3), 41.
[2] Weiss, J., Zhang, H., & Zelenay, P. (2020). Recent progress in the durability of Fe-NC oxygen reduction electrocatalysts for polymer electrolyte fuel cells. Journal of Electroanalytical Chemistry, 875, 114696.
[3] Taşdemir, A., Iskandarani, B., Yürüm, A., Gürsel, S. A., & Kaplan, B. Y. (2021). CeO2 nanorod decorated NrGO additives for boosting PEMFC performance. International Journal of Hydrogen Energy, 46(63), 32250-32260.
Structure and Activity-Durability Tradeoff of Coated Fe-N-C Catalysts for the Oxygen Reduction Reaction
Authors: Jiao Li , Sougrati Moulay-Tahar , Jaouen Frederic 
Published: February 2024

Fe-based catalysts stand out for oxygen reduction reactions among the platinum group metal (PGM)-free catalysts for reducing the reliance on expensive and scarce platinum. With the endeavor of a PGM-free community, the state-of-the-art Fe-N-C catalysts have demonstrated encouraging initial activity in Proton Exchange Membrane Fuel Cell (PEMFC) 1-2. However, their long-term stability and durability remain a challenge, both in acidic liquid electrolyte cells and in single-cell PEMFCs3. Recently, a novel approach has demonstrated improved durability of Fe-N-C catalysts during ORR, which consisted of coating a pre-existing Fe-N-C with a thin carbon overlayer obtained via chemical vapor deposition of a metal-organic framework (ZIF-8), at 1100 °C4. However, the underlying mechanism for enhanced durability remains unclear. One of the keys to improved stability lies in the specific structure of the catalysts, including the coordination of the ORR-active iron atoms and the structure of the nitrogen-doped carbon matrix, especially the structure located at the top surface of catalysts. The CVD conditions that affect the structure of FeNC must be optimized, to achieve the optimal activity-durability trade-off.
This presentation will report on the structure, activity, and durability trends of a suite of FeNC catalysts coated at different CVD conditions. The key parameters have been investigated, such as deposition temperature, overlayer thickness, and iron speciation on their ORR activity and durability. The coated Fe-N-C catalysts have been evaluated for their activity/durability (in oxygenated environments) both in liquid electrolyte cells and PEMFCs. The coated Fe-N-C demonstrated inferior initial activity and improved durability (Figure 1). The correlation between the structural information derived from multiple techniques (XRD, Mossbauer spectroscopy, TEM, Raman spectroscopy, N2 sorption, etc) and their electrochemical behaviors will be discussed.
References

Jiao, L.; Li, J.; Richard, L. L.; Sun, Q.; Stracensky, T.; Liu, E.; Sougrati, M. T.; Zhao, Z.; Yang, F.; Zhong, S.; Xu, H.; Mukerjee, S.; Huang, Y.; Cullen, D. A.; Park, J. H.; Ferrandon, M.; Myers, D. J.; Jaouen, F.; Jia, Q., Nature Materials
2021, 20 (10), 1385-1391.

Mehmood, A.; Gong, M.; Jaouen, F.; Roy, A.; Zitolo, A.; Khan, A.; Sougrati, M.-T.; Primbs, M.; Bonastre, A. M.; Fongalland, D.; Drazic, G.; Strasser, P.; Kucernak, A., Nature Catalysis
2022, 5 (4), 311-323.

Martinez, U.; Komini Babu, S.; Holby, E. F.; Zelenay, P., Current Opinion in Electrochemistry
2018, 9, 224-232.

Liu, S.; Li, C.; Zachman, M. J.; Zeng, Y.; Yu, H.; Li, B.; Wang, M.; Braaten, J.; Liu, J.; Meyer, H. M.; Lucero, M.; Kropf, A. J.; Alp, E. E.; Gong, Q.; Shi, Q.; Feng, Z.; Xu, H.; Wang, G.; Myers, D. J.; Xie, J.; Cullen, D. A.; Litster, S.; Wu, G., Nature Energy
2022, 7 (7), 652-663.

Figure 1
Carbon Corrosion Behavior of Carbon Support Materials for PGM-Based Catalysts in PEM Fuel Cells
Authors: Merzdorf Thomas , Hornberger Elisabeth , Ott Sebastian , Riebel Laurin , Guo An , Schröer Pierre , Strasser Peter 
Published: February 2024

The proton exchange membrane fuel cell (PEMFC) is a promising device for the transportation sector of a fossil free society, using green hydrogen from water electrolysis as a clean and sustainable option. However, sluggish kinetics as well as durability issues limit the implementation until this day. Therefore, modifications to the platinum catalysts [1] and the carbon supports [2] are made to improve the overall performance and durability of the cathode catalyst system.
Herein, we present the investigation of the carbon corrosion behavior of different carbon support materials in PEMFCs using online nondispersive infrared (NDIR).The different carbon supports used for this study are commercial materials such as Vulcan, Ketjenblack EC-300J and Ketjenblack EC-600JD as well as self-synthesized mesoporous carbon nanodendrites (MCND). [3] The MCND support material is a highly porous high surface area carbon, which makes it a suitable candidate for fuel cell applications. Onto the support materials, Pt nanoparticles were deposited using a customized fluidized bed reduction reactor [4], resulting in similar Pt particle size and distribution onto the support material, thus making a comparison between different supports possible. Beginning of life (BOL) measurements in a single cell setup, as shown in Figure 1, show promising performance of the platinum catalyst supported on MCND (Pt/CMCND) compared to the platinum catalysts on commercial supports. Furthermore, we will present the investigated carbon corrosion behavior of the different support materials conducted by accelerated stress tests (AST) based on the DOE support degradation protocol. The online quantification of the evolved CO and CO2 from the cathode catalyst layer is measured using our online NDIR giving insight in the carbon corrosion resistivity of the different support materials. Together with the performance measurements, we develop a better understanding of the impact of the carbon support material on the performance and durability of the cathode catalyst layer.
Literature:
[1] Strasser, P; Kühl, S. Nano Energy
2016, 29, 166.
[2] Ott, S. et. al., Nat. Mater.
2020, 19 (1), 77-85.
[3] Numao, S. et al., Carbon
2009, 47, 306-312.
[4] Hornberger, E. et. Al. J. Electrochem. Soc. 2020, 167, 114509.

Figure 1: Air polarization curves of the four different catalysts under the following conditions: 80° C, 100% RH, 150 kPaabs backpressure, stoich.: 1.5 (H2) and 2 (air), min. flow: 50 ml/min (H2) and 800 ml/min (air).

Figure 1
Mesoporous Carbon Supported Catalyst for Heavy Duty Fuel Cells
Authors: Komini Babu Siddharth , Mckinney Samuel , Wang Xiaojing , Yu Haoran , Li Kui , Mccool Geoff , Zulevi Barr , Park Andrew , Cullen David A. , Borup Rod L. 
Published: February 2024

The interaction between the catalyst and the carbon support is crucial to both the performance and durability of the membrane electrode assembly (MEA) in a polymer electrolyte membrane fuel cell. Local oxygen transport resistance (RO2) has shown to be a significant contributor to the overpotential loss in the catalyst layer.1 Utilizing mesoporous carbon supports has shown to reduce RO2 compared to high surface area carbon and prevent ionomer poisoning of Pt inside the pores.2 Engineered catalyst supports (ECS) synthesized through templated organic precursor provides improved control of resulting carbon morphology.3 This work presents a detailed study of the performance and durability of the ECS supported catalyst. Effect of Pt weight percentage on the carbon support, ionomer loading, and the ionomer type on the catalyst performance and durability is presented. Figure 1 shows the performance at beginning of life (BOL) and end of life (EOL) after 90000 cycles, using US DOE’s electrocatalyst protocol, for MEAs with different ionomer loadings. Polarization curve, Pt accessibility through CO stripping, and RO2 from limiting current will be presented are measured at different intervals between BOL and EOL. Characterization of the Pt particle and catalyst layer structure performed at BOL and EOL will also be presented. This study highlights the value of the morphological and electrochemical evaluation to provide detailed insights into the catalyst and mesoporous carbon support interaction.

Acknowledgement

This research is supported by Technology Readiness Gross Receipts Tax Credit through New Mexico Legislature. This research is supported by U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the Million Mile Fuel Cell Truck Consortium (M2FCT).

References

1 Kongkanand, A. et al. Journal of Physical Chemistry Letters, 7, (7), 1127-1137, 2016.
2 Ramaswamy, N. et al. Journal of The Electrochemical Society, 167, (6), 064515, 2020.
3 Ramaswamy, N. US DOE Hydrogen and Fuel Cells Program: 2020 Annual Merit Review and Peer Evaluation Report, 2020.

Figure 1
CVD Growth Graphene Foam Functionalized with Platinum for Fuel Cells Applications
Authors: Ion-Ebrasu Daniela , Andei Radu Dorin , Negrila Constantin Catalin , Boerasu Iulian , Carcadea Elena , Marinoiu Adriana , Vasile Bogdan Stefan 
Published: February 2024

The development of catalysts with high activity for the ORR is essential to proton exchange membrane fuel cells (PEMFCs), since the majority of activation losses occur at the cathode and it turns into an interesting research area. In the present study, it is investigated the hydrothermal platinum functionalization of the CVD grown three-dimensional graphene foam (3D-GrFoam) using three concentrations of dihydrogen hexachloroplatinate (IV) hydrate [1]. The platinum functionalized graphene foam determined from XPS was 0.2at %, 0.3 at % and 0.4 at %, respectively.The catalytic activity towards ORR was analyzed from linear sweep voltammetry (LSV) plots recorded with a scan rate of 5 mV s-1 in oxygen saturated 0.5 M H2SO4. From the LSV curves and the Koutecky-Levich (K-L) plots for 0.4PtGrFoam as current density (mA-1 cm2
geo) vs. w-1/2 (rad s-1)-1/2), for various rotation speeds (among 250–1500 rpm) and different potentials (0.1 V-0.8 V). From the fitted K-L plots it is noticed a fair linear relationship at all potentials, that confirms the electroreduction of platinum. The number of transferred electrons is between 3.22 to 3.59 indicating the preponderance of the four-electron transfer mechanism in the ORR corresponding to the directly reduction of O2 to H2O.
1. Ion-Ebrasu, R.D. Andrei, S. Enache, S. Caprarescu, C. C. Negrila, C. Jianu, A. Enache, I. Boerasu, E. Carcadea, M. Varlam, B. S. Vasile, J. Ren, Materials 2021, 14, 4952.
(Invited) The Stability of Nanomaterials in Electrochemical Energy Conversion, Illustrated on Selected Examples
Authors: Ledendecker Marc 
Published: February 2024

Energy is the most valuable resource for human activity and the foundation for all human progress. Thereby, electrochemical processes are considered a crucial technology for our future society's energy landscape. Catalysts are fundamental components of these processes, and the ability to control their structure and composition during synthesis is essential for obtaining high-performance and stable catalysts while preserving critical resources. The stability of materials that can endure reaction conditions over extended periods is of immense significance. In nanoparticle systems, typical deactivation mechanisms include catalyst agglomeration, dissolution, coalescence, Ostwald ripening, support corrosion, or poisoning.[1] In this conference contribution, I will discuss the prerequisites for stable electrocatalysts using selected examples. I will demonstrate how the catalyst's environment and support material can prevent degradation based on our recent observations.[2-5]
[1] Y. Shao-Horn, W. C. Sheng, S. Chen, P. J. Ferreira, E. F. Holby, D. Morgan, Top. Catal., 46, 285-305, 2007, J. C. Meier, I. Katsounaros, C. Galeano, H. J. Bongard, A. A. Topalov, A. Kostka, A. Karschin, F. Schüth, K. J. J. Mayrhofer, Energy & Environmental Science 2012, 5, 9319-9330.
[2] D. Göhl, H. Rueß, A. M. Mingers, K. J. J. Mayrhofer, J. M. Schneider, M. Ledendecker, J. Electrochem. Soc., 169, 011502, 2022
[3] D. Göhl, A. Garg, P. Paciok, K. J. Mayrhofer, M. Heggen, Y. Shao-Horn, R. E. Dunin-Borkowski, Y. Román-Leshkov, M. Ledendecker, Nat. Mater., 19, 287-291, 2020
[4] D. Göhl, H. Rueß, M. Pander, A. R. Zeradjanin, K. J. Mayrhofer, J. M. Schneider, A. Erbe, M. Ledendecker, J. Electrochem. Soc., 167, 021501, 2020
[5] M. Ledendecker, S. Krick Calderón, C. Papp, H. P. Steinrück, M. Antonietti, M. Shalom, Angew. Chem. Int. Ed., 54, 12361-12365, 2015
Effect of Cerium Oxide Nanoparticle Morphology on the Performance and Durability of Hydrogen/Air Fuel Cell Electrodes
Authors: Yarar Kaplan Begum , Iskandarani Bilal , Zabara Mohammed Ahmed , Yurum Alp , Alkan Gursel Selmiye 
Published: February 2024

There has been considerable research on ceria (CeO2) in catalytic applications due to its excellent redox property, providing the ability to easily shift Ce4+ to Ce3+ [1]. This leads to a change in oxidation states and the number of oxygen vacancy defects by minimal activation energy. The catalytic property of CeO2 is directly related to its oxygen storage capacity (OSC) which stands for the quantity of oxygen vacancies that a crystal structure is capable to host. In our previous study, utilization of CeO2 as an additive provided excellent oxygen storage capacity and enhancement in the performance and durability for the cathode of the PEM fuel cell [2]. In the present study, CeO2-based additives with different morphologies including cubic (c-CeO2), rod (r-CeO2), and octahedral (o-CeO2) incorporated into the cathode and their impact on the ORR, performance, and durability of the electrode for hydrogen/air fuel cell was explored. As the first step, CeO2 additives were successfully synthesized via a hydrothermal method and characterized physical techniques such as BET, XRD, and SEM. In the prepared electrodes, the Pt/C and Nafion® loadings were kept constant while varying the CeO2/(Pt/C) loadings. The results have shown an overall enhancement in fuel cell performance (up to 31.8% increase in maximum power density) for cubic-CeO2 loadings reaching only 0.075 mg.cm-2 (20% CeO2). In addition, a fixed additive amount (20%) was employed for different morphologies as well. It was determined that all morphologies exhibited an enhancement in the overall performance compared to Pt/C-based electrode.

References:

[1] Campbell, T.C. and Peden, C.H.F. Science
,

309
(5735), 713-714, (2005).
[2] Taşdemir, A., Iskandarani, B., Yürüm, A., Gürsel, S.A., Yarar Kaplan, B. Int J Hydrogen Energy, 46(63), 32250-32260, (2021).
Improved Activity and Durability of Carbon-Coated Pd and PdNi Anode Catalysts in AEMFC
Authors: Sgarbi Ricardo , Doan Huong , Bibent Nicolas , Amigues Simon , Jaouen Frederic , Chatenet Marian 
Published: February 2024

Anion exchange membrane fuel cells (AEMFC) have received growing attention due to the strategic potential of using low content (or absence) of PGM catalysts in the electrodes.[1] Completely PGM-free cathode catalysts are well established in those conditions,[2] while the anode ones remain critical in terms of the beginning-of-life activity and long-term performance.[3] The widely Pt- and Pd-based catalysts degrade mainly by nanoparticles detachment and agglomeration in alkaline conditions.[4] These degradations may be slowed down by wrapping the nanoparticles in some carbon layers (called carbon-coated), that prevent also metal oxidation and leaching into the electrolyte in the RDE setup.[5] However, the performance in AEMFC of carbon-coated nanoparticle catalysts is still unclear.
Here, two groups (previously characterized in RDE, XRD, IL-TEM, XPS and ICP-MS techniques[5]) of carbon-coated catalysts were investigated in 5 cm2 AEMFC: monometallic Pd (Pd@C/C) and bimetallic PdNi (PdNi@C/C) nanoparticles supported on carbon, and compared them to unprotected ones (Pd/C and PdNi/C). The four different anode catalysts were compared for a fixed Pd anode loading of 0.27 mgPd cm-2, and were combined with a ZIF-8 derived Fe-N-C cathode catalyst (previously developed Fe0.5-NH3). The Pd@C/C and PdNi@C/C reached superior initial performances (700 and 1300 mA cm-2) than the Pd/C and PdNi/C references (300 and 390 mA cm-2) at 0.6 V and Tcell
= 60 °C. This translates into an initial activity trend of PdNi@C/C > PdNi/C > Pd@C/C > Pd/C. After 12 h durability test at a cell voltage of 0.3 V, the AEMFC with the PdNi@C/C based anode exhibits a dramatically higher retention of performance (95%) than the cells with Pd/C (55%) and PdNi/C (70%) anodes. These results evidence the robustness of bimetallic carbon-coated nanoparticle catalysts for AEMFC anodes.

Figure 1
The Oxygen Reduction Reaction on Pt and Ag Catalysts in Alkaline Media in Rrde and Half-Cell Setups
Authors: Rampf Alexander , Braig Michael , Passerini Stefano , Zeis Roswitha 
Published: February 2024

Understanding the Oxygen Reduction Reaction (ORR) in alkaline media is essential to optimize alkaline fuel cells or metal-air batteries. The catalytic activity of various ORR catalysts has usually been evaluated via Rotating (Ring) Disk Electrode (R(R)DE) measurements. However, using an electrolyte with dissolved oxygen at low KOH concentrations measured in a microampere regime at room temperature does not reflect the real cell conditions.1 Yet, RRDE is still a valuable tool for probing the reaction pathway of catalysts in alkaline media. Our study combined traditional RRDE with Gas Diffusion Electrodes (GDEs) half-cell measurements using Pt and Ag catalysts.
The polarization curve of Pt-GDE exhibits a kink near 0.8 V vs. RHE leading to a significant potential drop. This specific feature can be explained by the RRDE results, which display an increased peroxide formation in that potential region due to the adsorption/desorption of hydroxyl adsorbates.2 However, Ag does not exhibit such behavior since the peroxide formation is below typical operating potentials. Depending on the operating conditions, Ag can catalyze the ORR more effectively than Pt in alkaline conditions while significantly reducing production costs. Furthermore, our study presents a general approach for evaluating ORR catalysts under experimentally challenging conditions such as elevated temperature and high KOH molarity.
References:
(1) Ehelebe, K.; Schmitt, N.; Sievers, G.; Jensen, A. W.; Hrnjić, A.; Collantes Jiménez, P.; Kaiser, P.; Geuß, M.; Ku, Y.-P.; Jovanovič, P.; et al. Benchmarking Fuel Cell Electrocatalysts Using Gas Diffusion Electrodes: Inter-lab Comparison and Best Practices. ACS Energy Lett.
2022, 7, 816–826.
(2) Ramaswamy, N.; Mukerjee, S. Fundamental Mechanistic Understanding of Electrocatalysis of Oxygen Reduction on Pt and Non-Pt Surfaces: Acid versus Alkaline Media. Advances in Physical Chemistry
2012, 2012, 1–17.

Figure 1