Balancing Activity and Stability in a Ternary Au-Pd/Fe Electrocatalyst for ORR with High Surface Coverages of Au

Sluggish kinetics of the oxygen reduction reaction (ORR) and low durability of ORR catalysts in polymer electrolyte membrane fuel cells (PEM-FCs) requires a continued search for advanced catalysts. Bimetallic catalysts demonstrate enhanced kinetics due to the optimized electronic properties from alloying but can suffer from poor stability of the active metals. Herein we report our findings that while bulk gold is catalytically inactive, high coverages (> 0.6 monolayer) of Au deposited on a Pd₃Fe(111) surface were highly active and stable. These properties of Au-modified Pd₃Fe(111) surfaces are associated with initial formation of 2D nanostructures at step edges and the transition of 2D to 3D nanostructures under reaction conditions. The balancing of activity and stability in this ternary Au-Pd/Fe electrocatalyst provides a potential candidate for non-Pt, highly stable ORR catalysts. Similar nanostructures and conditions may be able to activate gold for use in other electrocatalytic reactions.