Improving the activity and stability of Pt-based core-shell nanocatalysts for proton exchange membrane fuel cell (PEMFC), while lowering Pt loading, has been one of the big challenges in electrocatlysis. Here, using density functional theory (DFT) we report the effect of adding Au as the third element to enhance the durability and activity of Ni@Pt core-shell nanoparticles (NPs) during the oxygen reduction reaction (ORR). Our results show that the durability and activity of a Ni@Pt NP can be finely tuned by controlling Au concentration and distribution. For a NiAu@Pt NP, the durability can be greatly promoted by thermodynamically favorable segregation of Au to replace the Pt atoms at vertex, edge and (100) facets on the shell, which are known to contribute much less to ORR activity than (111) facets, while still keeping the ORR activity on the active Pt(111) shell as high as that of Ni@Pt nanoparticle, which strongly depends on the direct interaction with Ni interlayer. Our results not only highlight the importance of interplay between surface strain on the shell and the interlayer-shell interaction in determining the durability and activity, but also provide the guidance on how to maximize the usage of Au to optimize the performance of core-shell (Pt) nanoparticles. Such understanding allows us to discover the novel NiAu@Pt nanocatalyst for the ORR.

Design core-shell nanocatalysts for oxygen reduction reaction from first principles

251st National Meeting (2016)

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