Pt Nanoplates Interfaced by Atomic CrO _x Layer Enable High‐Power‐Density and Durable PEM Fuel Cells

ABSTRACT The dissolution of Pt‐based alloy catalysts remains a formidable challenge for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. Herein, we report a new stage‐dependent competitive adsorption synthetic strategy for making 2D Pt nanoplates interfaced by a stable, atomic‐layer CrO x (Pt–CrO x NPs). This strategy leverages strong Pt–CrO x electronic interactions to fundamentally suppress Pt dissolution and meantime greatly enhance ORR activity. The resulting Pt–CrO x NPs demonstrate exceptional electrochemical stability with a negligible 3.3% decline in mass activity after 30,000 cycles, significantly outperforming commercial Pt/C. Furthermore, the Pt–CrO x NPs‐based membrane electrode assembly in an H 2 ‐O 2 /air cell delivers an outstanding peak power density of 2.30/1.05 W cm −2 with a low cathode Pt loading of 0.1 mg Pt cm −2 , and 16 mV voltage loss at 0.8 A cm −2 after accelerated stability tests. Density functional theory (DFT) calculations further unveil that the Pt–CrO x interface weakens the binding of oxygenated intermediates to Pt and significantly increases the Pt vacancy formation energy, consequently suppressing Pt dissolution and contributing to superior fuel cells durability.