Modeling Core‐Shell Pt–Co Catalyst Degradation in Fuel Cells Using a Continuum Approach

Numerical modeling of bimetallic (BM) alloyed core‐shell catalyst degradation is particularly important, since it enables the evaluation of the complex interplay between the shell thickness‐dependent specific activity (SA), the resistance to electrochemical degradation, and the derivation of mitigation of poisoning resulting from dissolution of the alloying metal. Current state‐of‐the‐art BM particle degradation models rely on a discrete approach, which is restricted to the simulation of a limited selection of core‐shell particles rather than a full 2D distribution. In this study these challenges are overcome by developing a new BM catalyst degradation model based on the continuity equation and the rate of change of particle radii. Its applicability has been demonstrated by modeling the evolution of a 2D distribution of core and shell nanoparticles, and evaluating the loss of catalyst activity, not only in terms of changes in the catalyst's surface area, but also due to shell thickness‐dependent SA variation. These new features of the model are further utilized to design a degradation mitigation strategy based on mixing BM and pure platinum catalysts in order to limit the alloying metal dissolution, as well as to minimize the loss of electrochemical activity.