High Oxygen Reduction Efficiency and Durability of Nano-Honeycomb Pt₃(NiFeCo) Replenished by High-Entropy Metallic Glass Support

Developing low-Pt oxygen reduction reaction (ORR) catalysts with high efficiency and robustness is critical for practical fuel cells. The most advanced ORR catalysts either feature high percentages of Pt (>70 at.%) or exhibit poor durability when reducing Pt loading. Herein, a multicomponent solid-solution Pt₃(FeCoNi) honeycomb nano-framework supported by the specially designed high-entropy metallic glass (MG) is reported for efficient ORR. This hybrid catalyst with a low surface Pt loading of 5.79 µg cm^-2 displays exceptional mass and specific activities of 7.02 A mg_pt ^-1 and 8.15 mA cm_Pt ^-2 at 0.9 V, respectively, which are ≈15 and 22 times higher compared with commercial Pt/C. The analyses reveal the weakened chemisorption of oxygenated species, which is induced by the strong strain and ligand effects originating from the synergistic multicomponent alloying. This in turn enhances the intrinsic ORR activity. Moreover, benefiting from a unique replenishment behavior, the hybrid catalyst delivers ultra-high durability with negligible activity decay even after 50 000 potential cycles. This mechanism is achieved by sacrificing the interior MG supplementary support to dynamically compensate for the loss of catalytically active surface. The work provides an alternative way to design more efficient and durable low-Pt electrocatalysts for electrochemical devices.