Shape-controlled Pt-Ni alloys usually offer an exceptional electrocatalytic activity toward the oxygen reduction reaction (ORR) of polymer electrolyte membrane fuel cells (PEMFCs), whose tricks lie in well-designed structures and surface morphologies. In this paper, a novel synthesis of truncated octahedral PtNi₃₅ alloy catalysts that consist of homogeneous Pt-Ni alloy cores enclosed by NiO-Pt double shells through thermally annealing defective heterogeneous PtNi_3.5 alloys is reported. By tracking the evolution of both compositions and morphologies, the outward segregation of both PtO_x and NiO are first observed in Pt-Ni alloys. It is speculated that the diffusion of low-coordination atoms results in the formation of an energetically favorable truncated octahedron while the outward segregation of oxides leads to the formation of NiO-Pt double shells. It is very attractive that after gently removing the NiO outer shell, the dealloyed truncated octahedral core-shell structure demonstrates a greatly enhanced ORR activity. The as-obtained truncated octahedral Pt₂₁Ni core-shell alloy presents a 3.4-folds mass-specific activity of that for unannealed sample, and its activity preserves 45.4% after 30000 potential cycles of accelerated degradation test (ADT). The peak power density of the dealloyed truncated octahedral Pt_2.1Ni core-shell alloy catalyst based membrane electrolyte assembly (MEA) reaches 679.8 mW/cm², increased by 138.4 mW/cm² relative to that based on commercial Pt/C.

形状受控的Pt-Ni合金通常对聚合物电解质膜燃料电池（PEMFC）的氧还原反应（ORR）具有出色的电催化活性，其诀窍在于精心设计的结构和表面形态。本文报道了一种新型的截短八面体PtNi ₃₅合金催化剂的合成方法，该催化剂由有缺陷的异质PtNi _3.5合金通过热退火，由NiO-Pt双壳包围的均相Pt-Ni合金核组成。通过跟踪组成和形态的演变，PtO _x的向外偏析在Pt-Ni合金中首先观察到Ni和NiO。据推测，低配位原子的扩散导致形成能量上有利的截短的八面体，而氧化物的向外偏析导致形成NiO-Pt双壳。非常有吸引力的是，在轻轻去除NiO外壳后，脱合金的截短的八面体核-壳结构显示出大大增强的ORR活性。截断后的八面体Pt ₂₁ Ni核壳合金呈现出的质量比活性是未退火样品的3.4倍，在30000个潜在的加速降解试验（ADT）循环后，其活性保留45.4％。脱合金截短八面体Pt _2.1的峰值功率密度Ni核-壳合金催化剂基膜电解质组件（MEA）达到679.8 mW / cm ²，相对于基于商业Pt / C的膜电解质组件增加了138.4 mW / cm ²。