Activity and Durability of Platinum-Based Electrocatalysts Supported on Bare or Fluorinated Nanostructured Carbon Substrates

Asset, Tristan; Chattot, Raphaël; Maillard, Frédéric; Dubau, Laëtitia; Ahmad, Yasser; Batisse, Nicolas; Dubois, Marc; Guérin, Katia; Labbé, Fabien; Metkemeijer, Rudolf; Berthon‐Fabry, Sandrine; Chatenet, Marian

doi:10.1149/2.031806jes

Cited by 29 publications

(15 citation statements)

References 111 publications

(160 reference statements)

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“…For example, grafting F to form more robust CF bonds by fluorination presented a great promise in enhancing the stability of disordered carbon support. [ 78 ] Another strategy is to develop highly ordered (graphitized) carbon materials that have significantly enhanced stability. However, the graphitized carbon usually lacks of anchoring sites for PGM particles and has weak catalyst‐support interaction and low surface area, leading to decreased active site density.…”

Section: Low‐pgm Catalysts For Pem Fuel Cellsmentioning

confidence: 99%

“…As reported in ref. [78], the fluorination is strong enough to break original CC bonds on graphitic carbon surfaces, thus leading to weakened stability of ordered carbon structures. The trade‐off between surface defect and electrochemical stability still needs further study.…”

Section: Low‐pgm Catalysts For Pem Fuel Cellsmentioning

confidence: 99%

“…Recently, the surface modification, e.g., fluorination, was proved to alleviate carbon oxidation. [ 127 ] The underlying mechanisms are attributed to the hydrophobic surfaces and electron‐withdrawing properties (decreased electron density) of carbon matrix after fluorination, [ 127 ] probably as well as the formation of more robust CF bonds replacing the originally unstable CO bonds [ 78 ] as discussed in Section 3.2.2. The ordered carbon precursors are also likely helpful to form stable carbon structure in final catalysts.…”

Section: Pgm‐free Catalysts For Pem Fuel Cellsmentioning

confidence: 99%

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Low‐PGM and PGM‐Free Catalysts for Proton Exchange Membrane Fuel Cells: Stability Challenges and Material Solutions

et al. 2020

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Fuel cells as an attractive clean energy technology have recently regained popularity in academia, government, and industry. In a mainstream proton exchange membrane (PEM) fuel cell, platinum‐group‐metal (PGM)‐based catalysts account for ≈50% of the projected total cost for large‐scale production. To lower the cost, two materials‐based strategies have been pursued: 1) to decrease PGM catalyst usage (so‐called low‐PGM catalysts), and 2) to develop alternative PGM‐free catalysts. Grand stability challenges exist when PGM catalyst loading is decreased in a membrane electrode assembly (MEA)—the power generation unit of a PEM fuel cell—or when PGM‐free catalysts are integrated into an MEA. More importantly, there is a significant knowledge gap between materials innovation and device integration. For example, high‐performance electrocatalysts usually demonstrate undesired quick degradation in MEAs. This issue significantly limits the development of PEM fuel cells. Herein, recent progress in understanding the degradation of low‐PGM and PGM‐free catalysts in fuel cell MEAs and materials‐based solutions to address these issues are reviewed. The key factors that degrade the MEA performance are highlighted. Innovative, emerging material concepts and development of low‐PGM and PGM‐free catalysts are discussed.

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Section: Low‐pgm Catalysts For Pem Fuel Cellsmentioning

confidence: 99%

Section: Low‐pgm Catalysts For Pem Fuel Cellsmentioning

confidence: 99%

Section: Pgm‐free Catalysts For Pem Fuel Cellsmentioning

confidence: 99%

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Low‐PGM and PGM‐Free Catalysts for Proton Exchange Membrane Fuel Cells: Stability Challenges and Material Solutions

et al. 2020

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“…For instance, RGO nanoplatelets act as spacers between the platinized carbon black agglomerates, decreasing the catalytic layer percolation threshold (electronic conductivity) [12] and enhancing mass transfer [11]. Carbon black durability could be increased, for example, through the preparation of composites with stable oxides [13,14] or using any heteroatom doping approaches [15]. Several alternatives, such as carbon nanotubes [16], nanofibers [17], mesoporous carbons [18], and graphene-based materials [19][20][21][22][23], have been considered.…”

Section: Introductionmentioning

confidence: 99%

Reduced Graphene Oxide-Supported Pt-Based Catalysts for PEM Fuel Cells with Enhanced Activity and Stability

et al. 2021

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Platinum (Pt)-based electrocatalysts supported by reduced graphene oxide (RGO) were synthesized using two different methods, namely: (i) a conventional two-step polyol process using RGO as the substrate, and (ii) a modified polyol process implicating the simultaneous reduction of a Pt nanoparticle precursor and graphene oxide (GO). The structure, morphology, and electrochemical performances of the obtained Pt/RGO catalysts were studied and compared with a reference Pt/carbon black Vulcan XC-72 (C) sample. It was shown that the Pt/RGO obtained by the optimized simultaneous reduction process had higher Pt utilization and electrochemically active surface area (EASA) values, and a better performance stability. The use of this catalyst at the cathode of a proton exchange membrane fuel cell (PEMFC) led to an increase in its maximum power density of up to 17%, and significantly enhanced its performance especially at high current densities. It is possible to conclude that the optimized synthesis procedure allows for a more uniform distribution of the Pt nanoparticles and ensures better binding of the particles to the surface of the support. The advantages of Pt/RGO synthesized in this way over conventional Pt/C are the high electrical conductivity and specific surface area provided by RGO, as well as a reduction in the percolation limit of the components of the electrocatalytic layer due to the high aspect ratio of RGO.

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“…There are indications that the fluorination of materials in acidic media improves their oxidative stability. Examples of such systems include Nafion ionomer, Pt/C, and platinum group metal-free catalysts for PEM fuel cells [ 30 , 31 , 32 ]. Recently, we also fluorinated a highly active FeN x -doped carbon catalyst in the hopes that fluorine would increase its stability in PEM fuel cells [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

Non-PGM Electrocatalysts for PEM Fuel Cells: A DFT Study on the Effects of Fluorination of FeNx-Doped and N-Doped Carbon Catalysts

et al. 2021

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Fluorination is considered as a means of reducing the degradation of Fe/N/C, a highly active FeNx-doped disorganized carbon catalyst for the oxygen reduction reaction (ORR) in PEM fuel cells. Our recent experiments have, however, revealed that fluorination poisons the FeNx moiety of the Fe/N/C catalytic site, considerably reducing the activity of the resulting catalyst to that of carbon only doped with nitrogen. Using the density functional theory (DFT), we clarify in this work the mechanisms by which fluorine interacts with the catalyst. We studied 10 possible FeNx site configurations as well as 2 metal-free sites in the absence or presence of fluorine molecules and atoms. When the FeNx moiety is located on a single graphene layer accessible on both sides, we found that fluorine binds strongly to Fe but that two F atoms, one on each side of the FeNx plane, are necessary to completely inhibit the catalytic activity of the FeNx sites. When considering the more realistic model of a stack of graphene layers, only one F atom is needed to poison the FeNx moiety on the top layer since ORR hardly takes place between carbon layers. We also found that metal-free catalytic N-sites are immune to poisoning by fluorination, in accordance with our experiments. Finally, we explain how most of the catalytic activity can be recovered by heating to 900 °C after fluorination. This research helps to clarify the role of metallic sites compared to non-metallic ones upon the fluorination of FeNx-doped disorganized carbon catalysts.

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Activity and Durability of Platinum-Based Electrocatalysts Supported on Bare or Fluorinated Nanostructured Carbon Substrates

Cited by 29 publications

References 111 publications

Low‐PGM and PGM‐Free Catalysts for Proton Exchange Membrane Fuel Cells: Stability Challenges and Material Solutions

Low‐PGM and PGM‐Free Catalysts for Proton Exchange Membrane Fuel Cells: Stability Challenges and Material Solutions

Reduced Graphene Oxide-Supported Pt-Based Catalysts for PEM Fuel Cells with Enhanced Activity and Stability

Non-PGM Electrocatalysts for PEM Fuel Cells: A DFT Study on the Effects of Fluorination of FeNx-Doped and N-Doped Carbon Catalysts

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