Understanding the degradation of <scp>Pt</scp> nanoparticles in a fuel cell electrode via identical location electron tomography
Notice bibliographique
Résumé
The degradation and high cost of electrodes materials used in proton exchange membrane fuel cells (PEMFCs) are major barriers limiting their commercialization in automotive vehicles [1]. The search for more affordable electrode materials has focused on controlling the surface structure and composition of novel multi‐metallic catalytic nanoparticles on high surface area support membrane [2]. During fuel cell operation, the catalyst nanoparticles can dissolve, re‐deposit and agglomerate, resulting in electrochemical surface area losses, and an associated decrease in catalyst activity [3]. It is therefore critical to understand the degradation mechanism of the nanoparticle catalysts during electrochemical aging in a fuel cell electrodes in order to improve the performance and lifetime of PEMFCs. Here we characterize a newly proposed fuel cell cathode material, comprised of nano‐particulate platinum on a NbO x ‐carbon hybrid support, using identical location electron tomography. A full HAADF‐STEM tomographic tilt series of several representative clusters were obtained before and after acclerated stress tests (30,000 cycles from 0.6 to 1.0 V in an electrochemical cell). Preliminary results are summarized in Figure 1. A three dimensional (3D) schematic of a simple PEMFC shows the overall structure and location of the cathode electrode catalyst material used in this study. Pt nanoparticles, a few nanometers in diameter, decorate the complex, 3D NbO x ‐carbon hybrid support structure, imaged by HAADF STEM under identical conditions in (b) before and after electrochemical cycling and at two tilts separated by 40 0 . The 3D tomographic reconstructions of the structure are aligned and compared in (c). The high fidelity of the reconstructions and the relatively small overall changes observed in the structure enabled the semi‐automated matching of over 500 individual Pt nanoparticles before and after cycling (d). The semi‐automatized approach was accomplished with the aid of quantitative image analysis techniques including histogram normalization and maximum entropy thresholding, and alignment of the before and after reconstructions via a singular valued decomposition of the reconstructed Pt centroids matrix. Preliminary results suggest that a net leaching of the Pt into solution has occurred during cycling, indicated by the overall reduction in size of a vast majority of Pt nanoparticles (e). Analysis of 3D reconstructions obtained from Pt‐NbO x ‐carbon hybrid structures differing in their Pt/NbO x ratio are underway to better elucidate the role of NbO x in the degradation of Pt. Identical location electron tomography before and after electrochemical cycling has provided valuable insight into the degradation mechanism of the PEMFC electrode during cycling, enabling more informed decisions for the design of high‐performance durable electrode materials.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».