View article

Shape-controlled Pt-based bimetallic nanocrystals with ultrathin Pt-rich surfaces are appealing electrocatalysts for some key electrochemical reactions such as the oxygen reduction reaction (ORR) because of the synergistic tuning of topological atom configuration and strengthened electronic effects. However, it is rather challenging to fabricate such particular structures that can remain intact in harsh electrochemical environments, as such Pt-based nanocatalysts are unable to simultaneously achieve both unparalleled activity and robust stability. Here, a facile surface engineering strategy is proposed and employed to atomically tailor the near-surface structure of the Pt_1.5Ni octahedra. The engineered Pt–Ni octahedra consist of an ultrathin Pt-rich shell (∼two atomic layers) and Pt-rich bulk composition. The optimized octahedral catalyst exhibits superior specific and mass activity (7.7 mA/cm² _Pt and 1.9 A/mg _Pt at 0 …