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Simulations of the oxidation and degradation of platinum electrocatalysts

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peer-reviewed

Erstveröffentlichung
2019-12-26
Authors
Kirchhoff, Björn
Braunwarth, Laura
Jung, Christoph
Jónsson, Hannes
Fantauzzi, Donato
et al.
Wissenschaftlicher Artikel


Published in
Small ; 16 (2020), 5. - Art.-Nr. 1905159. - ISSN 1613-6810. - eISSN 1613-6829
Link to original publication
https://dx.doi.org/10.1002/smll.201905159
Faculties
Fakultät für Naturwissenschaften
Institutions
Institut für Elektrochemie
External cooperations
Helmholtz-Institut Ulm
Document version
published version (publisher's PDF)
Abstract
Oxidative degradation of cuboctahedral platinum nanoparticles is simulated using reactive force fields and a random‐number‐based sampling scheme. Potential‐dependent phase diagrams, constructed from the resulting structures, predict thermodynamically stable surface oxides between 0.85 and 1.15 V versus standard hydrogen electrode. At potentials above 1.15 V, calculations suggest dissolution of the nanoparticle into smaller clusters of Pt6O8 stoichiometry. Abstract Improved understanding of the fundamental processes leading to degradation of platinum nanoparticle electrocatalysts is essential to the continued advancement of their catalytic activity and stability. To this end, the oxidation of platinum nanoparticles is simulated using a ReaxFF reactive force field within a grand‐canonical Monte Carlo scheme. 2–4 nm cuboctahedral particles serve as model systems, for which electrochemical potential‐dependent phase diagrams are constructed from the thermodynamically most stable oxide structures, including solvation and thermochemical contributions. Calculations in this study suggest that surface oxide structures should become thermodynamically stable at voltages around 0.80–0.85 V versus standard hydrogen electrode, which corresponds to typical fuel cell operating conditions. The potential presence of a surface oxide during catalysis is usually not accounted for in theoretical studies of Pt electrocatalysts. Beyond 1.1 V, fragmentation of the catalyst particles into [Pt6O8]4− clusters is observed. Density functional theory calculations confirm that [Pt6O8]4− is indeed stable and hydrophilic. These results suggest that the formation of [Pt6O8]4− may play an important role in platinum catalyst degradation as well as the electromotoric transport of Pt2+/4+ ions in fuel cells.
DFG Project THU
SFB 1316 / Transiente Atmosphärendruckplasmen - vom Plasma zu Flüssigkeiten zu Festkörpern / DFG / 327886311
Project uulm
GEP / Verbundprojekt: Grundlagen elektrochemischer Phasengrenzen (GEP) - Teilvorhaben: Theoretische Untersuchungen an elektrochemischen Grenzschichten / BMBF / 13XP5023D
GEP / Verbundprojekt: Grundlagen elektrochemischer Phasengrenzen (GEP) - Teilvorhaben: Theoretische Untersuchungen an elektrochemischen Grenzschichten / BMBF / 13XP5023D
Is supplemented by
https://onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2Fsmll.201905159&file=smll201905159-sup-0001-SuppMat.pdf
Subject headings
[GND]: Elektrokatalyse | Brennstoffzelle | Oxidation
[LCSH]: Electrocatalysis | Fuel cells | Oxidation | Platinum catalysts
[Free subject headings]: ReaxFF
[DDC subject group]: DDC 530 / Physics | DDC 540 / Chemistry & allied sciences | DDC 620 / Engineering & allied operations
License
CC BY-NC-ND 4.0 International
https://creativecommons.org/licenses/by-nc-nd/4.0/

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DOI & citation

Please use this identifier to cite or link to this item: http://dx.doi.org/10.18725/OPARU-40988

Kirchhoff, Björn et al. (2022): Simulations of the oxidation and degradation of platinum electrocatalysts. Open Access Repositorium der Universität Ulm und Technischen Hochschule Ulm. http://dx.doi.org/10.18725/OPARU-40988
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