Role of Surface Iron in Enhanced Activity for the Oxygen Reduction Reaction on a Pd₃Fe(111) Single‐Crystal Alloy

Working together: Pd0.9Fe0.1–Pd3Fe(111) (see picture, Pd adatoms yellow, Fe purple, Pd blue-green, O red, H white) displays enhanced performance for the oxygen reduction reaction with five to eight times higher activity than Pd(111). The high catalytic activity may originate from a cooperative effect of a segregated Pd layer with its large tendency to remove surface O species by protonation and active Fe with its ability to dissociate O2.