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17. Review on the Degradation Mechanisms of Metal-N-C Catalysts for the Oxygen Reduction Reaction in Acid Electrolyte: Current Understanding and Mitigation Approaches

Author

Kumar, Kavita, Dubau, Laetitia, Jaouen, Frédéric, Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI), Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), Université de Montpellier (UM), ANR-16-CE05-0007,CAT2CAT,Des catalyseurs aux cathodes: Une approche d'architecture contrôlée d'électrode pour pile PEM à base de métaux abondants(2016), ANR-19-CE05-0039,ANIMA,Aérogels de carbone poreux dopés à l'azote et avec des métaux abondants pour des assemblages membrane-électrodes efficaces et durables(2019), ANR-21-CE05-0021,DEEP,Pile à combustible à membrane échangeuse d'anions alliant haute performance et chargement en métaux précieux ultrabas(2021), and European Project: 779366,CRESCENDO

Subjects
[CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry
Abstract

International audience; One bottleneck hampering the widespread use of fuel cell vehicles, in particular of proton exchange membrane fuel cells (PEMFCs), is the high cost of the cathode where the oxygen reduction reaction (ORR) occurs, due to the current need of precious metals to catalyse this reaction. Electrochemists tackle this issue in the short/medium term by developing catalysts with improved utilization or efficiency of platinum, and in the longer term, by developing catalysts based on Earth-abundant elements. Considerable progress has been achieved in the initial performance of Metal-Nitrogen-Carbon (Metal-N-C) catalysts for the ORR, especially with Fe-N-C materials. However, until now, this high performance cannot be maintained for sufficiently long time in operating PEMFC. The identification and mitigation of the degradation mechanisms of Metal-N-C electrocatalysts in the acidic environment of PEMFCs has therefore become an important research topic. Here, we review recent advances in the understanding of the degradation mechanisms of Metal-N-C electrocatalysts, including the recently identified importance of combined oxygen and electrochemical potential. Results obtained in liquid-electrolyte and PEMFC device are discussed, as well as insights gained from in situ and operando techniques. We also review the mitigation approaches that the scientific community has hitherto investigated to overcome the durability issues of Metal-N-C electrocatalysts.

Published
2023
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24. Structural disorder in ORR electrocatalysis: operation mode, practical descriptors to quantify and foreseen challenges

Author

Chattot, Raphaël, Atlan, Clément, Viola, Arnaud, Chatelier, Corentin, Martens, Isaac, Roiron, Camille, Drnec, Jakub, Bordet, Pierre, Richard, Marie‐ingrid, Dubau, Laetitia, Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI), Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), European Synchroton Radiation Facility [Grenoble] (ESRF), Matériaux, Rayonnements, Structure (NEEL - MRS), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), ANR-19-ENER-0008,BRIDGE,Vers l'intégration de catalyseurs performants dans des électrodes de pile à combustible efficaces(2019), ANR-14-CE05-0003,HOLLOW,Au-delà des électrocatalyseurs traditionnels : des nanoparticules creuses de métal noble pour applications PEMFC(2014), European Project: 818823,CARINE, Maillard, Frédéric, Vers l'intégration de catalyseurs performants dans des électrodes de pile à combustible efficaces - - BRIDGE2019 - ANR-19-ENER-0008 - ANR-BMBF - VALID, Appel à projets générique - Au-delà des électrocatalyseurs traditionnels : des nanoparticules creuses de métal noble pour applications PEMFC - - HOLLOW2014 - ANR-14-CE05-0003 - Appel à projets générique - VALID, and Coherent diffrAction foR a look Inside Nanostructures towards atomic rEsolution: catalysis and interface - CARINE - 818823 - INCOMING

Subjects
[CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.CATA]Chemical Sciences/Catalysis
Abstract

International audience; Due to strain and ligand effects, the simultaneous presence of concave and convex surfaces and their highly-defective nanostructure (atomic vacancies, grain boundaries), highly defective hollow PtNi/C electrocatalysts have proven to enhance remarkably the oxygen reduction reaction (ORR) kinetics [1,2]. Likewise, PtNi aerogel [3], jagged PtNi nanowires [4,5] feature both high concentration of structural defects and enhanced ORR activity. On the other hand, and inspired from single crystal approach, nanostructured octahedral-shaped PtNi/C electrocatalysts exhibiting only Pt(111) facets are among the most active ORR electrocatalysts [6,7]. This presentation will show how structure-activity-stability relationships of these two classes of materials can be unified via two descriptors derived from structural and electrochemical parameters respectively [8,9]. A special emphasis will be given on the stability trends of these two families of ORR electrocatalysts.

Published
2022

26. Recycling process of Membrane Electrode Assembly of PEMFC

Author

Dubelley, Florence, Svecova, Lenka, Robert, Mylène, Guillet, François, Bas, Corine, Dubau, Laetitia, Iojoiu, Cristina, Chatenet, Marian, and Charvin, Nicolas

Subjects
[SPI.MAT] Engineering Sciences [physics]/Materials
Published
2022

30. Fe-N-Carbon aerogel catalyst for oxygen reduction reaction

Author

Ge, Hongxin, Jaouen, Frederic, Bibent, Nicolas, Kumar, Kavita, Dubau, Laetitia, Maillard, Frédéric, Berthon-Fabry, Sandrine, Centre Procédés, Énergies Renouvelables, Systèmes Énergétiques (PERSEE), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Electrochimie Interfaciale et Procédés (EIP), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI), Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), ANR, ANR-19-CE05-0039,ANIMA,Aérogels de carbone poreux dopés à l'azote et avec des métaux abondants pour des assemblages membrane-électrodes efficaces et durables(2019), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)

Subjects
oxygen reduction reaction, non-precious metal catalysts, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry, proton-exchange membrane fuel cells
Abstract

International audience; Proton exchange membrane fuel cell (PEMFC)s are an excellent energy conversion device for wide application of hydrogen, especially for portable or transportation applications. To reduce the total cost of these devices, non-precious-metal catalysts (NPMCs) have shown promises in replacing platinum-based catalysts. Among NPMCs, iron-nitrogen-carbon (Fe-N-C) catalysts subclass are the most mature. These catalysts are based on nitrogen (N) coordinated iron (Fe) ions embedded in a carbon (C) matrix acting as catalytically active centers. Numerous studies have focused on promoting their catalytic performance towards the oxygen reduction reaction (ORR). Nevertheless, such materials remain less performant than carbon-supported platinum nanoparticles (Pt/C), leading to ca. 3-10 times thicker cathodes, and associated mass transport limitations.Carbon aerogels are ideal candidates to synthesize Fe-N-C catalysts with tuneable mass transport properties thanks to their tridimensional open texture, tailored pore size distribution from micro to macropores and their good electrical conductivity. Herein, we show the promises of Fe-N-C aerogels synthesized a “one pot” sol-gel method comprising formation of a Fe-doped resorcinol (R)-formaldehyde (F)-melamine (M) hydrogel, and followed by carbon dioxide (CO2) supercritical drying, and high temperature pyrolysis under N2 and NH3 atmosphere. By introducing ligands in the synthesis mixture, we modified the chemical environment of the Fe precursor. The resulting changes in morphology, ORR activity and mass transport properties are investigated a rotating disk electrode (RDE) set-up and a PEMFC device.

Published
2021

31. Defect propagation at the anode in Polymer Electrolyte Membrane Fuel Cells

Author

Touhami, Salah, Crouillere, Marie, Barboza-da-silva, Helen, Mainka, Julia, Dillet, Jérôme, Nayoze-Coynel, Christine, Bas, Corine, Dubau, Laetitia, Kaddouri, Assma El, Dubelley, Florence, Druart, Florence, CAUFFET , GILLES, Chatenet, Marian, Rosini, Sébastien, Bultel, Yann, Micoud, Fabrice, Lionel, Flandin, Chadebec, Olivier, Lottin, Olivier, Laboratoire Énergies et Mécanique Théorique et Appliquée (LEMTA ), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Genèse et Usage d'Interfaces Durables pour l'Energie (GUIDE), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI), Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), G2Elab-Electronique de puissance (G2Elab-EP), Laboratoire de Génie Electrique de Grenoble (G2ELab ), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Laboratoire d'Innovation pour les Technologies des Energies Nouvelles et les nanomatériaux (LITEN), Institut National de L'Energie Solaire (INES), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Electrochimie Interfaciale et Procédés (EIP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), and Charvin, Nicolas

Subjects
[SPI.MAT] Engineering Sciences [physics]/Materials, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract

International audience; Defaults propagation in Membrane Electrode Assemblies (MEA) of Polymer Electrolyte Membrane Fuel Cells (PEMFC) was investigated through an Accelerated Stress Test (AST) consisting load (and thus potential) cycling, load driven RH cycling and Open Circuit Voltage. Customized MEA without and with several defects at the anode Catalyst Layer (CL), i.e. lack or over thickness, at two different locations (near the hydrogen inlet or near the hydrogen outlet) were fabricated and subjected to the AST. Electrochemical characterization was performed periodically using a segmented cell which allows to follow the evolution of the cell performance, as well as anode and cathode and ElectroChemical Surface Area (ECSA) over the test period with a spatial resolution along the gas channels. The primary results indicate a significant impact of the default on the aging rates in all cases, as well as a significant impact on the default location in the case of the MEA with a default of the anode CL near the hydrogen inlet: we observed a default propagation along the hydrogen flow direction monitored through the evolution of local ECSA and its standard variation between the beginning and the end of the test. The segments neighboring the defect seemed more affected than the others. No significant impact was evidenced however when the default was located near the anode outlet. These observations were completed by post-mortem analysis of the membrane following the AST: the MEA with a lack of anode CL evidenced thinning of the PFSA layer on the cathode side near the location of the default.

Published
2021

32. Impact of a chemical-mechanical ex-situ aging on PFSA membranes for fuel cells

Author

Robert, Mylène, Kaddouri, Assma El, Perrin, Jean-Christophe, Dubau, Laetitia, Mozet, Kevin, Daoudi, Meriem, Dillet, Jérôme, Morel, Jean-Yves, André, Stéphane, Lottin, Olivier, Laboratoire Énergies et Mécanique Théorique et Appliquée (LEMTA ), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), and Lottin, Olivier

Subjects
[CHIM.POLY] Chemical Sciences/Polymers, [CHIM.POLY]Chemical Sciences/Polymers, [CHIM.GENI]Chemical Sciences/Chemical engineering, [SPI.GPROC] Engineering Sciences [physics]/Chemical and Process Engineering, [CHIM.OTHE] Chemical Sciences/Other, [CHIM.GENI] Chemical Sciences/Chemical engineering, [SPI.FLUID]Engineering Sciences [physics]/Reactive fluid environment, [CHIM.CATA] Chemical Sciences/Catalysis, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, [SPI.FLUID] Engineering Sciences [physics]/Reactive fluid environment, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.OTHE]Chemical Sciences/Other, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021

34. Proton Exchange Membrane Fuel Cell With Enhanced Durability Using Fluorinated Carbon As Electrocatalyst

Author

Ahmad Yasser, Guérin Katia, Dubau Laetitia, Chatenet Marian, and Berthon-Fabry Sandrine

Subjects
Environmental sciences, GE1-350
Abstract

This study evaluates the fluorination of a carbon aerogel and its effects on the durability of the resulting electrocatalyst for Proton Exchange Membrane Fuel Cell (PEMFC). Fluorine has been introduced before or after platinum deposition. The different electrocatalysts are physico-chemically and electrochemically characterized, and the results discussed by comparison with commercial Pt/XC72 from E-Tek. The results demonstrate that the level of fluorination of the carbon aerogel can be controlled. The fluorination modifies the texture of the carbons by increasing the pore size and decreasing the specific surface area, but the textures remain appropriate for PEMFC applications. Two fluorination sites are observed, leading to both high covalent C-F bond and weakened ones, the quantity of which depends on whether the treatment is done before or after platinum deposition. The order of the different treatments is very important. The presence of platinum contributes to the fluorination mechanism, but leads to amorphous platinum rather inactive towards the Oxygen Reduction Reaction. Finally, a better durability was demonstrated for the fluorinated then platinized catalyst compared both to the same but not fluorinated catalyst and to the reference commercial material (based on the loss of the electrochemical real surface area after accelerated stress tests).

Published
2017
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35. Electrochemical Adsorption Trends from Synchrotron X-Ray Diffraction

Author

Chattot, Raphael, Martens, Isaac, Braesch, Guillaume, Sibert, Eric, Dubau, Laetitia, Maillard, Frédéric, Chatenet, Marian, Drnec, Jakub, Chatenet, Marian, European Synchroton Radiation Facility [Grenoble] (ESRF), Electrochimie Interfaciale et Procédés (EIP), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI), Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), and Université Grenoble Alpes (UGA)

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

International audience

Published
2021

36. Improving Zinc Porous Electrode Architecture for Secondary Alkaline Battery

Author

Caldeira, Vincent, Dubau, Laetitia, Thiel, Julien, Chatenet, Marian, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Chatenet, Marian

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

37. Pt and hollow PtCo nanoparticles supported on carbon xerogels for PEM fuel cell catalyst layers

Author

Zubiaur, Anthony, Asset, Tristan, Deschamps, Fabien, Dubau, Laetitia, Maillard, Frédéric, Job, Nathalie, Université de Liège, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry
Abstract

International audience; Proton Exchange Membrane Fuel Cell electrocatalysts are commonly made of Pt/carbon black nanoparticles about 3 nm in diameter [1]. However, Pt nanoparticles are not stable under operating conditions and the use of carbon black does not allow control of the electrode nanostructure while this feature is key to mass transport properties. In this work, nanostructured carbon xerogels (CX) were used to synthesize supported plain Pt (Fig. 1a) and hollow PtCo nanoparticles (Fig. 1b) since that type of support leads to better reactant diffusion within the pore texture [2]. The addition of Co leads to the Pt lattice contraction, and thus to much higher catalytic activity towards oxygen reduction reaction while the hollow structure allows for relatively good metal utilization ratio despite the large particle size. PtCo/CX catalysts with 10 wt.% Pt were prepared; residual Co content ranged from 0.3 to 4.6 wt.%. These catalysts were thoroughly characterized using physico-chemical and electrochemical techniques, including Accelerated Stress Tests (ASTs) in in complete fuel cell configuration using a classical Pt/carbon black at the anode. ASTs consist in sharp voltage increase and decrease between 0.6 and 1.0 V to accelerate the catalyst ageing. Results show that the hollow PtCo/CX catalysts display much better stability than pure Pt/CX and Pt/carbon black samples. Indeed, while the performances of Pt nanoparticles continually decrease with ageing time, the current-voltage curves obtained with PtCo/CX hollow particles stabilize after a while. The reasons for enhanced stability probably lies in the large size and regular shape of the hollow nanoparticles.

Published
2019

38. Oxygen Evolution Reaction Investigation on Model Catalysts in Acidic Medium: electro-oxidation and catalytic activity of Ir(111), Ir(210) and nanostructured Ir(210)

Author

Scohy, Marion, Dubau, Laetitia, Martin, Vincent, Abbou, Sofyane, Sibert, Eric, Gilles, Bruno, Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Science et Ingénierie des Matériaux et Procédés (SIMaP ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and SIBERT, Eric

Subjects
[CHIM.OTHE] Chemical Sciences/Other, [CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.OTHE]Chemical Sciences/Other
Abstract

International audience; Proton exchange membrane water electrolysers (PEMWEs) are perceived as one of the most promising technology for a clean hydrogen production but the sluggish oxygen evolution reaction (OER, anodic reaction) kinetics and the poor stability of the anodic material still limit their widespread development [1]. Iridium oxides (IrO2) are ones of the most active electrocatalysts for the OER [2], able to maintain high OER kinetics over the long term in the harsh operating conditions of a PEMWE anode [3]. Considering the low abundance of iridium on the Earth's crust and its high cost, designing and synthesizing tailored OER nanocatalysts is an essential step. Switching from bulk surfaces to nanocatalysts requires investigations at atomically smooth model surfaces such as single crystals [4]. In this study, the effect of different crystal facets of Ir electrodes (Ir(111), Ir(210) and nanostructured Ir(210)) on the initial catalytic performance for the OER were compared. To go further, an ageing test consisting of applying 1.7 V vs. RHE for 2h was conducted to evaluate the stability of these surfaces. The amount of iridium dissolved was quantified by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) (Figure 1B). Atomic Force Microscopy (AFM) was used to study the surface morphologies and the chemical compositions were obtained by X-ray Photoelectron Spectroscopy (XPS). Although the surface structure (low-coordinated atoms and surface defects) and composition play a role on the initial catalytic performances, these differences vanish upon ageing (Figure 1A). By establishing the structure-activity-stability relationships, this fundamental study demonstrates the impact of low-coordinated atoms on the iridium dissolution and the correlation between the oxide composition and the OER activity. This study will help to improve the understanding of iridium electrocatalytic behavior upon OER and to design efficient catalysts for PEMWEs.

Published
2019

39. Benefits and Limitations of Metal-Oxide Supports in Proton-exchange Membrane Fuel Cells and Water Electrolyzers

Author

Cognard, Gwenn, Claudel, Fabien, Dubau, Laetitia, Chatenet, Marian, Solà-Hernández, Lluís, Ozouf, Guillaume, Beauger, Christian, Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre Procédés, Énergies Renouvelables, Systèmes Énergétiques (PERSEE), MINES ParisTech - École nationale supérieure des mines de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[CHIM.CATA]Chemical Sciences/Catalysis
Abstract

International audience; Decreasing the size of metallic materials to nanometre-size dimensions has always proven beneficial to increase their mass activity for electrocatalytic reactions in proton-exchange membrane fuel cells (PEMFC) and proton-exchange membrane water electrolyzers (PEMWE). However, such strategy requires adequate supports which are (i) electron-conducting, (ii) corrosion-resistant, and (iii) exhibiting opened and interconnected architecture compatible with facile gas-transport and ionomer insertion. Due to a standard potential close to 0.2 V vs. the normal hydrogen electrode, carbon corrosion of classical carbon supports slowly proceeds at a PEMFC cathode, the kinetics of this reaction being even faster at the anode of a PEMWE; this calls for alternative support materials. It is possible to meet the first and second requirements by doping tin oxide (SnO 2 , TO), a metal oxide that is stable at pH close to 0, and 0 < E < 1.5 V vs. RHE and T = 80°C, with Sb [1-6] or Nb [2]. The third requirement can also be met by structuring the metal oxide in an aerogel form. However, benefits and limitations of this strategy under simulated or real-life operating conditions remain poorly explored and will be the focus of this presentation. Here, we synthesized Pt or Ir nanoparticles and supported them onto antimony-doped (ATO) or niobium-doped (NTO) tin oxide aerogels featuring tailored porosity and tested their initial and long-term performance in simulated PEMFC or PEMWE operating conditions. By combining chemical, physical and electrochemical techniques, we show that Sb and Sn atoms are dissolved from ATO and poison the Pt catalytic sites in a PEMFC cathode. This process is accelerated during potential excursions at low electrode potential, e.g. during electrochemical characterizations or kinetic measurements. Sb dissolution also takes place in the potential range where a PEMWE anode operates. This leads to a Sb-poor surface covering a core featuring a Sb content close to the nominal on the long-term and restricts the capacity of the metal nanoparticles to exchange electrons. Despite such observations, better long-term stability under accelerated stress tests was evidenced compared to conventional carbon based supports, both in simulated PEMFC or PEMWE operating conditions.

Published
2019

40. Atomistic Picture of Platinum Structural Changes During Electrocatalysis and Mitigation Strategies for Long Term Stability

Author

Drnec, Jakub, Ruge, Martin, Fuchs, Timo, Chattot, Raphaël, Martens, Isaac, Stubbs, Natalie, Reikowski, Finn, Rahn, Bjorn, Honkimaki, Veijo, Bizzotto, Dan, Stettner, Jochim, Dubau, Laetitia, Maillard, Frédéric, Magnussen, Olaf, harrington, david, European Synchrotron Radiation Facility (ESRF), Christian-Albrechts University of Kiel, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), University of Victoria [Canada] (UVIC), University of British Columbia (UBC), and Maillard, Frédéric

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, [CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry, [CHIM.CATA]Chemical Sciences/Catalysis
Abstract

International audience; The durability of an electro-active material (e.g. Pt catalyst in proton exchange membrane fuel cells (PEMFC)) is a major barrier, preventing faster commercialization of energy conversion and storage devices for stationary and transportation applications. In the case of PEMFC, the decrease in performance is partially due to irreversible processes in the catalyst layers, such as dissolution and morphology changes of Pt nanostructures. Even though these processes have been extensively studied in the past, there are still many important questions unanswered related to the actual degradation mechanisms [1 and references there-in]. Therefore further fundamental understanding of the Pt oxidation, reduction, dissolution, and restructuring mechanisms, togehter with their atomistic picture, is clearly needed in order to incorporate the state-of-the-art catalysts into the PEMFC device and make the technology more commercially competitive. I will discuss the results of in-situ and operando structural X-ray studies performed on various Pt single crystal surfaces (Pt(111), Pt(100)) and on nanoparticle catalysts (NP) during the electrochemical oxide formation and its reduction [2-8]. We use advanced synchrotron based diffraction techniques to gain a detailed atomistic picture of the place-exchange (PE), dissolution and restructuring taking place in idealized conditions of the half cells and in PEMFC during operation. Severe surface reorganization due to the PE process occurs in the potential range relevant to the ORR. Interestingly, the exact position of the PE atom on the surface is the decisive factor which determines the extent of surface restructuring and dissolution. If the PE atom is positioned exactly above its vacancy (e.g. on Pt(111) at low potentials), the PE process is reversible. However, if the PE atom moves laterally from its vacancy, the diffusion barrier prevents the diffusion back to the vacancy and the surface restructures and dissolves in the reduction step. The surface orientation, potential, and time play a decisive role in this process. The PE and surface restructuring have severe consequences as they cause activity loss of the state-of-the-art shaped NP catalysts (octahedra, cubes) in accelerated stress tests and they are also responsible for the poor stability of core-shell nanostructures. It is also one of the main reasons why the incorporation of advanced Pt based catalysts into the next generation PEMFCs remains a challenging task. Yet nothing is lost and possible knowledge based mitigation strategies, involving additives, particular core-shell structures and defects engineering, can be developed. For example, a new class of defectous Pt catalysts show extraordinary stability, as the reorganization does not significantly alter the morphology which is solely responsible for the high activity [9]. In these materials the defects are used to tune the electronic structure, instead of more traditional approaches such as alloying or shape engineering.References:[1] Kongkanand and Ziegelbauer, J. Phys. Chem. C, 116 (2012), [2] J. Drnec et al, Electrochim. Acta, 224 (2017), [3] M. Ruge et al, J. Am. Chem. Soc., 139 (2017), [4] M. Ruge et al, J. Electrochem. Soc., 164 (2017) , [5] J. Drnec et al, Current Opinion Electrochem., 4 (2017), [6] J. Drnec et al, Electrochem. Comm., 84 (2017), [7] Fuch et al., in preparation, [8] Martens et al., in preparation, [9] Chattot et al., Nature Materials, 17(2018)

Published
2019

41. Electrocatalysis of oxygen reduction reaction for proton exchange membrane fuel cell application

Author

Dubau, Laetitia, Asset, Tristan, Chattot, Raphaël, Chatenet, Marian, Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Maillard, Frédéric

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, [CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry
Abstract

International audience; The ever-growing energy demand worldwide and the announced end of the so-called "fossil fuel era" are currently boosting the development of electrochemical energy technologies, such as fuel cells, batteries and supercapacitors. In proton-exchange membrane fuel cells (PEMFC), special effort has been paid to improve the catalytic activity for the oxygen reduction reaction (ORR) of the cathodic material, its stability and to decrease its precious metal content. Pt/C or bimetallic Pt 3 M/C electrocatalysts (with M = Cr, Fe, Co, Ni, Cu) are now classically used at the cathode because of their enhanced oxygen reduction reaction (ORR) activity (Figure 1). However, an increased ORR activity is meaningless if it cannot be maintained over time. This presentation will describe the stability issues encountered by Pt 3 M/C cathode materials in model and real operating conditions 1. From this results, mitigation strategies in terms of design of architectured nanoparticles will be addressed 2,3. Figure 1. Components of a single PEM fuel cell: schematic (left); scanning electron microscopy (SEM) image of the MEA (middle) and transmission electron microscopy (TEM) images of a commercial Pt/C catalyst.

Published
2019

43. Surface distortion as a unifying concept and descriptor in oxygen reduction reaction electrocatalysis

Author

Maillard, Frédéric, Chattot, Raphaël, Bordet, Pierre, Drnec, Jakub, Asset, Tristan, Dubau, Laetitia, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Matériaux, Rayonnements, Structure (MRS), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), European Synchrotron Radiation Facility (ESRF), and Maillard, Frédéric

Subjects
[CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.CATA]Chemical Sciences/Catalysis
Abstract

International audience; The oxygen reduction reaction (ORR) is a key reaction for energy conversion and storage systems such as polymer electrolyte membrane fuel cells (PEMFCs). Studies on Pt and Pt-transition metal alloy single crystals have established that the ORR is best electrocatalyzed on bimetallic alloys and at (111) facets. Combining alloying and ensemble effects recently led to 20-30-fold enhancement of the specific activity (normalized per real cm 2 of catalyst) for the ORR on PtNi/C nanooctahedra relative to Pt/C nanoparticles. However, due to the highly oxidizing conditions of the PEMFC cathode, the stability of PtNi/C octahedra is poor in PEMFC cathode operating conditions, thus compromising their utilization in real devices. Strikingly, it also turned out recently that structurally-disordered PtNi nano-catalysts, such as hollow PtNi/C nanoparticles, dealloyed PtNi/C nanoparticles, PtNi aerogels or PtNi nanowires feature highly desirable and sustainable ORR activity (x 10-12 in specific activity relative to pure Pt/C). However, to date, the mechanisms of this unexpected ORR activity enhancement remain unclear, and prevent further development of this vital technology for a carbon-free energy future. To shed fundamental light onto these issues, state-of-the art PtNi/C nanocatalysts with distinct atomic composition, size, shape and density of disorder were synthesized. Their disorder was quantified experimentally, using the values of microstrain (a parameter accessible by the Rietveld refinement of wide-angle X-ray scattering patterns) that is representative of the local distortion of a crystal lattice. Thanks to ab initio calculations, the contributions of bulk and surface structural disorder were disentangled, and a new parameter, the surface distortion (SD), was established. The SD descriptor was used to rationalize the ORR activity enhancement of the two classes of materials (structurally-ordered and structurally-disordered), and to probe their stability in simulated PEMFC cathode operating conditions.

Published
2019

44. Shedding light on the degradation mechanism of PGM based carbon-supported electrocatalysts in alkaline media

Author

Lafforgue, Clémence, Maillard, Frédéric, Dubau, Laetitia, Chatenet, Marian, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Chatenet, Marian

Subjects
[CHIM] Chemical Sciences, [CHIM.CATA] Chemical Sciences/Catalysis, [CHIM]Chemical Sciences, [CHIM.CATA]Chemical Sciences/Catalysis, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

45. Oxygen Evolution Reaction Investigation on Model Catalysts in Acidic Medium: electro-oxidation and catalytic activity of Ir(111), Ir(210) and nanopyramids on Ir(210)

Author

Scohy, Marion, Gilles, Bruno, Dubau, Laetitia, Maillard, Frédéric, Sibert, Eric, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Science et Ingénierie des Matériaux et Procédés (SIMaP ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and SIBERT, Eric

Subjects
oxygen evolution, Iridium single crystals, [CHIM.OTHE] Chemical Sciences/Other, [CHIM.CATA] Chemical Sciences/Catalysis, electrocatalysis, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.OTHE]Chemical Sciences/Other, water electrolysis
Abstract

International audience; The need to increase the energy production from renewable sources and their intermittent nature currently boost the development of energy storage systems such as proton exchange membrane water electrolysers (PEMWEs)[1]. These systems are currently perceived as one of the most promising technology currently available. However, the sluggish oxygen evolution reaction (OER, anodic reaction) kinetics and the poor stability of the anodic material still limit their widespread development[2]. Iridium oxides (IrO2) are ones of the most active electrocatalysts for the OER[3], able to maintain high OER kinetics over the long term in the harsh operating conditions of a PEMWE anode[4]. Considering the low abundance of iridium on the Earth's crust and its high cost, designing and synthesizing tailored OER nanocatalysts is an essential step. Switching from bulk surfaces to nanocatalysts requires investigations at atomically smooth model surfaces such as single crystals[5]. The effect of different crystal facets of Ir electrodes (Ir(111), Ir(210) and nano-faceted Ir(210)) on the electro-oxidation and on the catalytic performance for the OER were compared. Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM) were used to correlate the OER performance to the surface morphology. The open structure was found to be the most active, with improved performance upon electro-oxidation. This study improves the comprehension of iridium electrocatalytic behavior upon oxidation and OER, and will help to design efficient catalysts for PEMWEs.

Published
2019

46. Distorted Surfaces for Electrocatalysis

Author

Chattot, Raphaël, Dubau, Laetitia, Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Maillard, Frédéric

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, [CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

47. Combining Identical-Location Transmission Electron Microscopy and X-Ray Photoelectron Spectroscopy to Unravel Unravelling Structure – Chemical Composition – Oxygen Evolution Reaction Activity

Author

Claudel, Fabien, Dubau, Laetitia, Berthomé, Gregory, Solà-Hernandez, Lluís, Beauger, Christian, Piccolo, L., Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Science et Ingénierie des Matériaux et Procédés (SIMaP ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre Procédés, Énergies Renouvelables, Systèmes Énergétiques (PERSEE), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), IRCELYON-Catalyse Hétérogène pour la Transition Energétique (CATREN), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM.CATA]Chemical Sciences/Catalysis, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

48. Unravelling the Degradation Mechanisms of Non-Precious Metal Oxygen Reduction Reaction Catalysts in PEMFC Cathode Relevant Conditions

Author

Kumar, Kavita, Gairola, Pryanka, Lions, Mathieu, Ranjbar-Sahraie, Nastaran, Mermoux, Michel, Dubau, Laetitia, Zitolo, Andrea, Jaouen, Frederic, Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Matériaux Interfaces ELectrochimie (MIEL ), Synchrotron SOLEIL (SSOLEIL), and Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

49. Degradation of PGM-Based Carbon Supported Electrocatalysts in Alkaline Media Studied by in situ Fourier Transform Infrared Spectroscopy

Author

Lafforgue, Clémence, Maillard, Frédéric, Dubau, Laetitia, Chatenet, Marian, Maillard, Frédéric, Electrochimie Interfaciale et Procédés (EIP ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.CATA]Chemical Sciences/Catalysis, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

50. Promoting Surface Distortion for Improved Fuel Cell Electrocatalysis

Author

Chattot, Raphaël, Dubau, Laetitia, Maillard, Frédéric, Maillard, Frédéric, Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and European Synchrotron Radiation Facility (ESRF)

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, [CHIM.CATA] Chemical Sciences/Catalysis, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry
Abstract

International audience; The electrochemical activation of oxygen is the cornerstone of electrochemical conversion and storage devices, such as fuel cells, metal-air batteries, and electrolysers. It is well established that Pt is the only metal that can catalyse efficiently the oxygen reduction reaction (ORR) in acidic electrolyte, the reaction limiting the performance of low temperature proton-exchange membrane fuel cells (PEMFCs). However, due to the high cost and scarcity of Pt, research efforts recently focused on enhancing simultaneously its intrinsic activity (specific activity i.e. the current produced per cm 2 of Pt) and its mass activity (the current produced per gram of Pt). Studies on Pt or PtNi single crystals have established that the ORR is a structure sensitive reaction, which is best electrocatalyzed on (111) facets in acidic electrolyte. Combining alloying and ensemble effects recently led to 20-30-fold enhancement of the specific activity for the ORR on PtNi/C nanooctahedra relative to Pt/C nanoparticles. However, due to the highly oxidizing conditions of the PEMFC cathode (high electrochemical potential, presence of oxygen, acidic pH), the stability of these "dream" catalysts was found poor in PEMFC cathode operating conditions, thus compromising their utilization in real devices 1. Strikingly, it also turned out recently that alloyed but structurally-disordered nanocatalysts, such as hollow PtNi/C nanoparticles, porous PtNi/C nanoparticles, PtNi aerogels or PtNi nanosponges also feature highly desirable and sustainable ORR activity (x 10-12 in specific activity relative to pure Pt/C). Even more striking, the ORR kinetics depends on the concentration of structural defects: the higher the structural disorder in a given nanocatalyst, the best is its intrinsic activity for the ORR but also other oxidation reactions 2. This talk will address our recent insights about the quantification and the role played by structural defects in heterogeneous electrocatalysis from the beaker cell to the fuel cell device. Our proposal is based on Rietveld refinement of wide angle high energy X-rays scattering measurements and high resolution electron microscopy for a broad range of nanocatalysts combined with density functional theory calculations (DFT) References:C. Cui, L. Gan, M. Heggen, S. Rudi, and P. Strasser, “Compositional segregation in shaped Pt alloynanoparticles and their structural behaviour during electrocatalysis,” Nat. Mater., vol. 12, no. 8, pp. 765–771, 2013.2. R. Chattot, T. Asset, P. Bordet, J. Drnec, L. Dubau, and F. Maillard, “Beyond strain and ligand effects:Microstrain-induced enhancement of the oxygen reduction reaction kinetics on various PtNi/Cnanostructures,” ACS Catal., vol. 7, pp. 398–408, 2017.3. R. Chattot et al., “Surface distortion as a unifying concept and descriptor in oxygen reduction reactionelectrocatalysis,” Nat. Mater., vol. 17, no. September, pp. 827–833, 2018.

Published
2019

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