Structurally Ordered Low‐Pt Intermetallic Electrocatalysts toward Durably High Oxygen Reduction Reaction Activity

Carbon‐supported low‐Pt ordered intermetallic nanoparticulate catalysts (PtM₃, M = Fe, Co, and Ni) are explored in order to enhance the oxygen reduction reaction (ORR) activity while achieving a high stability compared to previously reported Pt‐richer ordered intermetallics (Pt₃M and PtM) and low‐Pt disordered alloy catalysts. Upon high‐temperature thermal annealing, ordered PtCo₃ intermetallic nanoparticles are successfully prepared with minimum particle sintering. In contrast, the PtFe₃ catalyst, despite the formation of ordered structure, suffers from obvious particle sintering and detrimental metal–support interaction, while the PtNi₃ catalyst shows no structural ordering transition at all but significant particle sintering. The ordered PtCo₃ catalyst exhibits durably thin Pt shells with a uniform thickness below 0.6 nm (corresponding to 2–3 Pt atomic layers) and a high Co content inside the nanoparticles after 10 000 potential cycling, leading to a durably compressive Pt surface and thereby both high activity (fivefold vs a commercial Pt catalyst and 1.7‐fold vs an ordered PtCo intermetallic catalyst) and high durability (5 mV loss in half‐wave potential and 9% drop in mass activity). These results provide a new strategy toward highly active and durable ORR electrocatalysts by rational development of low‐Pt ordered intermetallics.