Pt₃Ni stands as one of the most active electrocatalysts for the oxygen reduction reaction (ORR). The activity varies with the morphology of the nanocrystals with a high activity observed for the octahedral shape where only the high density {111} crystallographic planes are exposed. Herein, the synthesis of 6 nm Pt₃Ni octahedral nanocrystals with a Pt enriched shell or cuboctahedral nanocrystals with a Ni enriched shell is described. Interestingly, the cuboctahedral nanocrystals display a six‐pointed star/skeleton of platinum, which features a very uncommon atomic distribution. In the synthesis, a decrease in the oxygen partial pressure induces the transition from octahedral to cuboctahedral morphology. The octahedral and cuboctahedral nanocrystals both demonstrate high ORR activity (1.1 mA cm⁻²_Pt and 1.2 A mg⁻¹_Pt at 0.9 V vs reversible hydrogen electrode (RHE) are the highest values obtained for PtNi‐20 and PtNi‐15, respectively). After exposure to oxidative conditions in the acidic electrolyte, the cuboctahedral nanoparticles with a pristine Ni‐rich skin show a Pt skin and retain their cuboctahedral morphology.

中文翻译：

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6 nm Pt3Ni纳米晶体中的八面体到立方八面体形状转变，用于氧还原反应电催化

Pt ₃ Ni是氧还原反应（ORR）最具活性的电催化剂之一。活性随纳米晶体的形态而变化，对于仅暴露高密度{111}晶体平面的八面体形状观察到高活性。在此，合成6 nm Pt ₃描述了具有富含Pt的壳的Ni八面体纳米晶体或具有富含Ni的壳的立方八面体纳米晶体。有趣的是，立方八面体纳米晶体显示出六点星形/骨架的铂，其原子分布非常罕见。在合成中，氧分压的降低引起从八面体到立方八面体形态的转变。八面体和立方八面体纳米晶体均显示出高ORR活性（1.1 mA cm ^-2 _Pt和1.2 A mg ^-1 _Pt相对于可逆氢电极（RHE）在0.9 V时分别是PtNi-20和PtNi-15的最高值）。暴露于酸性电解质中的氧化条件后，具有原始镍富集皮的立方八面体纳米颗粒显示出Pt皮并保留其立方八面体形态。