Platinum group metal free (PGM-free) electrocatalysts have important differences from their PGM counterparts. The embedded nature of the active site within the electrode support material and the heterogeneity due to pyrolysis processes make identification and improvement of activity and durability of such sites difficult. The Electrocatalysis Consortium (ElectroCat), a member consortium of DOE-EERE’s Energy Materials Network, is actively investigating how synthesis conditions dictate active site formation and how these active sites catalyze the oxygen reduction reaction (ORR) for proton exchange fuel cell cathodes. Additionally, these materials can suffer from rapid degradation, the mechanisms of which remain unknown. Local environment and potential may change the dominant activity loss mechanism, further complicating experimental studies. For both ORR reaction pathways and degradation pathways, detailed knowledge of active site structures would greatly aid in identifying mechanisms. Such knowledge would enable targeted improvement of activity and aid in mitigating activity loss. We will discuss recent theoretical progress considering active site structures, activity, and durability based on proposed structure models that include spontaneously evolved ligands that are believed to modify the site <i>in situ</i>.<br/>

Theoretical approaches for understanding the oxygen reduction reaction on PGM-free materials at the atomic scale

2019 Spring National Meeting

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