Pt x Co y Catalysts Degradation in PEFC Environments: Mechanistic Insights I. Multiscale Modeling

In this article, we focus on the understanding of the Pt x CO y electrocatalysts degradation in polymer electrolyte fuel cell (PEFC) environments. A multiscale atomistic/kinetic model is derived providing mechanistic insights on the impact of the nanostructure and operating conditions on Pt x CO y nanoparticles durability. On the basis of ab initio (AI) data, we identify favorable pathways of the oxygen reduction reaction (ORR) on Pt x CO y nanoparticles and of the competitive Pt-Co dissolution in acidic media. The derived AI kinetics is coupled to a description of the atomic reorganization at the nanoparticle level as a function of the cumulated Pt and Co mass losses. This nanoscale model is coupled with a transport microscale model of charges and O 2 through a PEFC cathode, and simulation sensitivity studies to operating conditions and initial compositions/morphologies are performed and complimented by microstructural and electrochemical characterizations carried out on aging direct liquid injection metallorganic chemical vapor deposition elaborated model electrodes detailed in our experimental companion paper.

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