High-performance transition metal-doped Pt₃Ni octahedra for oxygen reduction reaction

Bimetallic platinum-nickel (Pt-Ni) nanostructures represent an emerging class of electrocatalysts for oxygen reduction reaction (ORR) in fuel cells, but practical applications have been limited by catalytic activity and durability. We surface-doped Pt₃Ni octahedra supported on carbon with transition metals, termed M-Pt₃Ni/C, where M is vanadium, chromium, manganese, iron, cobalt, molybdenum (Mo), tungsten, or rhenium. The Mo-Pt₃Ni/C showed the best ORR performance, with a specific activity of 10.3 mA/cm² and mass activity of 6.98 A/mgPt, which are 81- and 73-fold enhancements compared with the commercial Pt/C catalyst (0.127 mA/cm² and 0.096 A/mg_Pt). Theoretical calculations suggest that Mo prefers subsurface positions near the particle edges in vacuum and surface vertex/edge sites in oxidizing conditions, where it enhances both the performance and the stability of the Pt₃Ni catalyst.