Integrating PtCo Intermetallic with Highly Graphitized Carbon Toward Durable Oxygen Electroreduction in Proton Exchange Membrane Fuel Cells.

Abstract

Exploiting robust and high-efficiency electrocatalysts for sluggish oxygen reduction reaction (ORR) is essential for proton exchange membrane fuel cells (PEMFCs) toward long-term operation for practical applications, yet remains challenging. Herein, the ordered PtCo intermetallic is reported with a Pt-rich shell loaded on a highly graphitized carbon carrier (O-PtCo@GCoNC) prepared by an impregnation annealing strategy. Systematic X-ray spectroscopic, operando electrochemical techniques and theoretical calculations reveal that thanks to the synergistic interaction of the core-shell PtCo intermetallic structure with a tailor-made Pt electronic configuration and highly graphitized carbon, O-PtCo@GCoNC exhibits significantly enhanced activity and stability toward ORR. Crucially, O-PtCo@GCoNC delivers a much-enhanced mass activity of 0.83 A mg_Pt ^-1 at 0.9 V versus reversible hydrogen electrode (RHE) in 0.1 m HClO₄, which only drops by 26.5% after 70 000 cycles (0.6-1.0 V vs RHE), and 10.8% after 10 000 cycles (1.0-1.5 V vs RHE), apparently overmatching Pt/C (0.19 A mg_Pt ^-1, 73.7%, and 63.1%). Moreover, O-PtCo@GCoNC employed as the cathode catalyst in H₂/air PEMFC achieves a superb peak power density (1.04 W cm^-2 at 2.06 A cm^-2), outperforming that of Pt/C (0.86 W cm^-2 at 1.79 A cm^-2). The cell voltage loss at 0.8 A cm^-2 is 28 mV after 30 000 cycles, outstripping the United States Department of Energy 2025 target.