Fe Single Atoms‐Induced Generation of Ternary PtCoFe Intermetallic Nanocrystals for Efficient Oxygen Reduction Catalysis

ABSTRACT Developing durable, low‐Pt oxygen reduction reaction (ORR) catalysts that simultaneously achieve high activity and stability remains a fundamental challenge for proton exchange membrane fuel cells (PEMFCs). Herein, we present a single‐atom (SAs)‐induced doping/transition strategy to prepare an electrocatalyst integrating Fe SAs and ternary PtCoFe intermetallic nanocrystals on porous N‐doped carbon. We demonstrate that the Fe SAs on the carbon support enable exclusive synthesis of L1 0 phase ternary PtCoFe intermetallics, whereas the Fe‐free carbon support yields the L1 2 phase binary Pt 3 Co intermetallics under similar conditions. The resulting L1 0 ‐PtCoFe intermetallic catalyst achieves excellent mass activity of 1.21 A mg Pt −1 at 0.9 V vs. RHE for acidic ORR, surpassing the commercial Pt/C by 5.0‐fold and exhibiting a decay of merely 8 mV in half‐wave potential after 30 000 cycles. In the PEMFC tests, the L1 0 ‐PtCoFe intermetallic catalyst delivers 1.14 A cm −2 at 0.65 V and a peak power density of 0.9 W cm −2 , exhibiting competitive performance among catalysts comprising intermetallic nanocrystals and SAs. Experimental data and theoretical calculations reveal that Fe incorporation optimizes oxygen adsorption via electronic effects and enhances stability by increasing vacancy formation energies, while the synergistic interplay between the PtCoFe nanoparticles and the Fe‐SA sites promotes efficient 4e ORR pathways. This work establishes a novel dual‐site catalyst architecture integrating atomically dispersed Fe sites with ordered ternary PtCoFe intermetallics, establishing a new paradigm for highly active and ultrastable low‐Pt fuel cell systems.