(327d) Face-Centered Tetragonal Pt Alloys of Fe & Co As Potential Catalysts for ORR

Authors: 
Sharma, S., Brown University
Peterson, A. A., Brown University
Proton exchange membrane fuel cells (PEMFCs) despite having advantages like high efficiency, sustainability and environment friendly operation suffer from the slow rate of oxygen reduction reaction at the cathode. The development of low-cost, efficient and stable electro-catalysts also remains a great challenge for the full-scale application of fuel cells.

In this study, we investigate special face-centered tetragonal (L10) FePt and CoPt alloys in a core-shell geometry as a potential catalyst for oxygen-reduction reactions via both dissociative and associative mechanism using density functional theory. The effect on ORR activity as a function of strain, ligand and number of Pt overlayers is studied with the help of binding energies of the reaction intermediates and full free energy landscape . A mechanistic eigenstress and eigenstrain model is used to understand the binding of a reaction intermediate as a function of strain. The ORR activity is further compared with that of Pt(111) surface.

We further show the that L10-FePt and L10-CoPt show higher bulk and surface stability than the native Pt. To enhance the stability of the Pt alloys, we look into the role of core-shell structure on surface stability as a function of Pt overlayers.