Epitaxial Growth of Ultrathin Highly Crystalline Pt-Ni Nanostructure on a Metal Carbide Template for Efficient Oxygen Reduction Reaction.

Structure engineering strategies such as core-shell and hollow nanostructures are effective pathways to improve the utilization of noble metals for catalysis. However, nowadays materials design based on these strategies still largely rely on precious metal templates. Herein, the epitaxial growth of highly crystalline Pt 3 Ni overlayer on earth-abundant nickel carbide is reported, forming Ni 3 C@Pt 3 Ni core-shell nanoparticles with a well-defined interface through a new lattice-match-directed synthetic strategy. Derived from such core-shell nanostructures, ultrathin highly crystalline Pt 3 Ni nanocages have an advantageous configuration of oxygen reduction reaction (ORR)-favored facets and inherently high active surface area for the ORR, bringing high mass activity and specific activity as much as 4.71 A mg Pt -1 and 5.14 mA cm -2 , which are 26 and 20 times to that of commercial Pt/C, respectively. This novel epitaxial growth of platinum opens up new avenues to rationally design highly active and economical electrocatalysts.