Synthesis of a Hexagonal-Phase Platinum–Lanthanide Alloy as a Durable Fuel-Cell-Cathode Catalyst

Carbon-supported platinum–lanthanide alloy nanoparticles are promising fuel-cell-cathode catalysts with enhanced electrocatalytic performance, but synthetic challenges remain because of high O affinity and very negative reduction potential of lanthanide elements. Herein, we demonstrate an industrially relevant impregnation approach for the general synthesis of a carbon-supported intermetallic hexagonal Pt5Ln (Ln = La, Ce, Pr, and Nd) catalyst by the interparticle-distance-dependent hydrogen-spillover strategy. We understand that increasing the available area of hydrogen spillover by narrowing the interparticle distance can facilitate the reduction of Ln around Pt, which guarantees the alloying of Pt with enough amount of Ln and thus promotes the formation of a thermodynamically favorable intermetallic hexagonal Pt5Ln phase. The prepared hexagonal Pt5Ln catalysts show enhanced oxygen reduction reaction activity in H2–O2 fuel cells and improved power density and durability in practical H2–air fuel cells. Our method is facile, universal, and scalable and opens a general route for intermetallic Pt–Ln catalyst synthesis that is conventionally challenging.