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.