Pt Nanoplates Interfaced by Atomic CrO_x Layer Enable High-Power-Density and Durable PEM Fuel Cells

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 H₂-O₂/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.