Atomic-scale restructuring of hollow PtNi/C electrocatalysts during accelerated stress tests

Dubau, Laëtitia; López‐Haro, Miguel; Durst, Julien; Maillard, Frédéric

doi:10.1016/j.cattod.2015.08.011

Cited by 26 publications

(24 citation statements)

References 60 publications

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“…This phenomenon is accompanied by a loss of the alloying transition metal and by a loss of polycrystallinity, which both lead to a drop in ORR performance. Obviously, the preferential dissolution of the alloying transition metal in operating PEMFC cathode is common to all bimetallic Pt‐alloys, but the morphological rearrangement occurring in porous nanomaterials actually magnifies the trend ,. A compilation of different accelerated stress tests performed on hollow PtNi/C nanocatalysts in our group has recently revealed that morphological restructuring is facilitated at potential exceeding 1.0 V vs .…”

Section: Discussionmentioning

confidence: 99%

“…or porous bimetallic NPs . Preferentially‐shaped or porous PtM/C catalysts are metastable by essence (the total surface energy of a face‐centred cubic structure is minimized by a spherical shape, hence any other shape leads to increased surface energy), and their rate of restructuring depends on the gas atmosphere,, on the temperature, and on the upper potential limit . Material solutions have been developed to kinetically mitigate the resulting compositional and morphological changes: they include decorating the catalytic surface with noble metal atoms ( e. g .…”

Section: Discussionmentioning

confidence: 99%

“…Obviously, the preferential dissolution of the alloying transition metal in operating PEMFC cathode is common to all bimetallic Pt-alloys, but the morphological rearrangement occurring in porous nanomaterials actually magnifies the trend. [80,203] A compilation of different accelerated stress tests performed on hollow PtNi/C nanocatalysts in our group has recently revealed that morphological restructuring is facilitated at potential exceeding 1.0 V vs. RHE. Such excursions cause formation of PtOH/PtO oxides, which are then reduced at low electrode potential (such as those encountered during real-life PEMFC cathode operation) leading to entrance of atomic vacancies in the metal lattice and surface buckling.…”

Section: Discussionmentioning

confidence: 99%

“…Nanocatalysts with superior ORR activity, such as nanostructured and mesostructured thin films, Pt and PtNi nanowires, PtM aerogels and hollow PtM NPs,, have recently been synthesized. A record ORR specific activity of 11.5 mA cm −2 Pt at 0.90 V vs .…”

Section: Oxygen Reduction Reaction Electrocatalysis In Acidic Electromentioning

confidence: 99%

“…Experimentally speaking, increasing the CN of Pt catalytic sites is possible by (i) introducing concave catalytic sites [67] or (ii) increasing the density of structural defects of the PtM nanocatalysts. Nanocatalysts with superior ORR activity, such as nanostructured and mesostructured thin films, [72] Pt [73] and PtNi [74] nanowires, PtM aerogels [75][76][77][78] and hollow PtM NPs, [14,[79][80][81][82][83][84][85][86][87][88][89] have recently been synthesized. A record ORR specific activity of 11.5 mA cm À2 Pt at 0.90 V vs. RHE (i. e. 33 times higher than a commercial Pt/C) was reported in 2016 on jagged Pt nanowires formed by complete dealloying of PtNi nanowires, thereby confirming that high ORR activity can be obtained without alloying ( Figure 2).…”

Section: Oxygen Reduction Reaction Electrocatalysis In Acidic Electromentioning

confidence: 99%

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A Review on Recent Developments and Prospects for the Oxygen Reduction Reaction on Hollow Pt‐alloy Nanoparticles

et al. 2018

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Due to their interesting electrocatalytic properties for the oxygen reduction reaction (ORR), hollow Pt-alloy nanoparticles (NPs) supported on high-surface-area carbon attract growing interest. However, the suitable synthesis methods and associated mechanisms of formation, the reasons for their enhanced specific activity for the ORR, and the nature of adequate alloying elements and carbon supports for this type of nanocatalysts remain open questions. This Review aims at shedding light on these topics with a special emphasis on hollow PtNi NPs supported onto Vulcan C (PtNi/C). We first show how hollow Pt-alloy/C NPs can be synthesized by a mechanism involving galvanic replacement and the nanoscale Kirkendall effect. Nickel, cobalt, copper, zinc, and iron (Ni, Co, Cu, Zn, and Fe, respectively) were tested for the formation of Pt-alloy/C hollow nanostructures. Our results indicate that metals with standard potential -0.4

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Oxygen Reduction Reaction Electrocatalysis In Acidic Electromentioning

confidence: 99%

Section: Oxygen Reduction Reaction Electrocatalysis In Acidic Electromentioning

confidence: 99%

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A Review on Recent Developments and Prospects for the Oxygen Reduction Reaction on Hollow Pt‐alloy Nanoparticles

et al. 2018

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Catalytic Nanoframes and Beyond

2020

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The ever‐increasing need for the production and expenditure of sustainable energy is a result of the astonishing rate of consumption of fossil fuels and the accompanying environmental problems. Emphasis is being directed to the generation of sustainable energy by the fuel cell and water splitting technologies. Accordingly, the development of highly efficient electrocatalysts has attracted significant interest, as the fuel cell and water splitting technologies are critically dependent on their performance. Among numerous catalyst designs under investigation, nanoframe catalysts have an intrinsically large surface area per volume and a tunable composition, which impacts the number of catalytically active sites and their intrinsic catalytic activity, respectively. Nevertheless, the structural integrity of the nanoframe during electrochemical operation is an ongoing concern. Some significant advances in the field of nanoframe catalysts have been recently accomplished, specifically geared to resolving the catalytic stability concerns and significantly boosting the intrinsic catalytic activity of the active sites. Herein, general synthetic concepts of nanoframe structures and their structure‐dependent catalytic performance are summarized, along with recent notable advances in this field. A discussion on the remaining challenges and future directions, addressing the limitations of nanoframe catalysts, are also provided.

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Platinum Dissolution in Realistic Fuel Cell Catalyst Layers

et al. 2021

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Pt dissolution has already been intensively studied in aqueous model systems and many mechanistic insights have been gained. Nevertheless,t ransfer of new knowledge to realworld fuel cell systems is still as ignificant challenge.T oc lose this gap,w ep resent an ovel in situ method combining ag as diffusion electrode (GDE) half-cell with inductively coupled plasma mass spectrometry (ICP-MS). With this setup,P t dissolution in realistic catalyst layers and the transport of dissolved Pt species through Nafion membranes were evaluated directly.W eo bserved that 1) specific Pt dissolution increased significantly with decreasing Pt loading, 2) in comparison to experiments on aqueous model systems with flowc ells,t he measured dissolution in GDE experiments was considerably lower,a nd 3) by adding am embrane onto the catalyst layer,Ptdissolution was reduced even further.All these phenomena are attributed to the varying mass transport conditions of dissolved Pt species,i nfluencing re-deposition and equilibrium potential.

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Atomic-scale restructuring of hollow PtNi/C electrocatalysts during accelerated stress tests

Cited by 26 publications

References 60 publications

A Review on Recent Developments and Prospects for the Oxygen Reduction Reaction on Hollow Pt‐alloy Nanoparticles

A Review on Recent Developments and Prospects for the Oxygen Reduction Reaction on Hollow Pt‐alloy Nanoparticles

Catalytic Nanoframes and Beyond

Platinum Dissolution in Realistic Fuel Cell Catalyst Layers

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