Sub-4 nm Pt5Sm Intermetallic Catalyst toward Efficient and Durable Oxygen Reduction for Fuel Cell Applications

It is remarkably attractive but challenging to develop fine Pt-rare-earth intermetallic catalysts toward efficient and stable oxygen reduction reaction (ORR) for fuel cell applications. In this work, an amino-assisted method was employed to prepare the carbon-supported Pt5Sm (Pt5Sm/C) catalyst, which exhibited an average size of 3.8 ± 1.0 nm with a core-shell structure consisting of a Pt-enriched surface over a hexagonal Pt5Sm intermetallic core. The introduction of Sm into the Pt lattice induced strong electron interactions between Sm and Pt and enhanced the resistance to Pt oxidation, thereby improving the catalytic kinetics and durability for the ORR. In rotating disk electrode tests, the Pt5Sm/C catalyst delivers a promising ORR activity of 430.3 A·gPt-1 with only a 10.3% loss after 30,000 cycles, significantly outperforming commercial Pt/C. Furthermore, in H2/air fuel cell tests, the Pt5Sm/C catalyst exhibited a peak power density of 853 mW·cm-2 with only a voltage drop of 56 mV at 0.8 A·cm-2 after 30,000 cycles. This work demonstrates that Pt-rare-earth intermetallic catalysts are promising candidates for high-performance and durable fuel cell applications.