Y‐Doped PtFeNi Medium‐Entropy Nano‐Alloy with Engineered (111) Facets for Enhanced Oxygen Reduction Reaction

ABSTRACT The development of highly efficient and durable Pt‐based oxygen reduction reaction (ORR) catalysts is paramount for the widespread adoption of proton exchange membrane fuel cells (PEMFCs). Herein, we present a novel Y‐doped PtFeNi medium‐entropy alloy catalyst, PtFeNiY 8 (PFNY 8 , 8% Y doping), synthesized via a simple one‐pot method, achieving preferential exposure of the highly active (111) crystal facet. Systematic experiments and density functional theory calculations demonstrate that Y doping lowers surface energy to promote the formation of the (111) crystal facet, with an optimal doping level of 8% achieving the most stable electronic structure and the most favorable d ‐band center. The PFNY 8 /C catalyst demonstrates outstanding ORR performance, with a half‐wave potential ( E 1/2 ) of 0.93 V, mass activity (MA) of 3.00 A mg −1 Pt , and excellent durability (after 80,000 ADT cycles, the E 1/2 decreases by only 11 mV, and the MA retention is 73.4%). Furthermore, in PEMFCs, PFNY 8 /C demonstrates a peak power density of 1.75 W cm −2 under H 2 /O 2 conditions, outperforming commercial Pt/C. This study offers valuable insights into the role of Y doping in tailoring nanoparticle morphology and facet exposure, presenting a new strategy for designing high‐performance Pt‐based catalysts for next‐generation PEMFCs.