High-performance transition metal–doped Pt 3 Ni octahedra for oxygen reduction reaction

Platinum (Pt) is an effective catalyst of the oxygen reduction reaction in fuel cells but is scarce. One approach to extend Pt availability is to alloy it with more abundant metals such as nickel (Ni). Although these catalysts can be highly active, they are often not durable because of Ni loss. Huang et al. show that doping the surface of octahedral Pt 3 Ni nanocrystals with molybdenum not only leads to high activity (∼80 times that of a commercial catalyst) but enhances their stability. Science , this issue p. 1230 Molybdenum-doped platinum-nickel nanocrystal catalysts exhibit high activity and durability for a key fuel cell 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 Pt 3 Ni octahedra supported on carbon with transition metals, termed M ‐Pt 3 Ni/C, where M is vanadium, chromium, manganese, iron, cobalt, molybdenum (Mo), tungsten, or rhenium. The Mo‐Pt 3 Ni/C showed the best ORR performance, with a specific activity of 10.3 mA/cm 2 and mass activity of 6.98 A/mg Pt , which are 81- and 73‐fold enhancements compared with the commercial Pt/C catalyst (0.127 mA/cm 2 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 Pt 3 Ni catalyst.