Size and Composition Dependence of Oxygen Reduction Reaction Catalytic Activities of Mo-Doped PtNi/C Octahedral Nanocrystals
Size and Composition Dependence of Oxygen Reduction Reaction Catalytic Activities of Mo-Doped PtNi/C Octahedral Nanocrystals
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DOI：
10.1021/acscatal.1c01761
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发表时间：
2021-08-31
期刊：
影响因子：
12.9
通讯作者：
Strasser, Peter
中科院分区：
文献类型：
--
作者：
Polani, Shlomi;MacArthur, Katherine E.;Strasser, Peter
八面体PtNi纳米催化剂的各种合成方案已经导致铂质量和氧还原反应的比活性的显着改善。然而，所获得的值仍然仅为从Pt 3 Ni单晶（111）表面测量的活性的十分之一。这些颗粒在潜在的循环过程中失去活性，主要是因为镍浸出和随后的形状损失。本文报道了不同粒径（6-14 nm）和组成的PtNi八面体催化剂的合成及其高催化氧还原反应活性。我们发现，钼掺杂，镍丰富，PtNi八面体催化剂表现出增强的稳定性，其未掺杂的对应。扫描透射电子显微镜与能量色散X-射线分析揭示了特定的元素分布的大小和组成的不同的催化剂。通过将高分辨率组成分析与电化学测量和在线电感耦合等离子体质谱相结合，可以将加速应力测试之前和之后的尺寸、形态和组成与氧还原反应活性相关联。八面体催化剂显示出高的电化学表面积和随着（111）晶面的表面积和Ni含量的增加而增加的比活性，导致高的质量活性。这些结果证明了增加PtNi纳米八面体催化剂的（111）表面积和Ni含量以改善氧还原反应的性能和稳定性的优点。
A variety of synthesis protocols for octahedral PtNi nanocatalysts have led to remarkable improvements in platinum mass and specific activities for the oxygen reduction reaction. Nevertheless, the values achieved are still only one tenth of the activity measured from Pt3Ni single-crystal (111) surfaces. These particles lose activity during potential cycling, primarily because of Ni leaching and subsequent loss of shape. Here, we present the syntheses and high catalytic oxygen reduction reaction activities of molybdenum-doped PtNi octahedral catalysts with different sizes (6-14 nm) and compositions. We show that the Mo-doped, Ni-rich, PtNi octahedral catalysts exhibit enhanced stability over their undoped counterpart. Scanning transmission electron microscopy with energy-dispersive X-ray analysis reveals the particular elemental distribution for the size and composition of the different catalysts. By combining high-resolution compositional analysis with electrochemical measurements and online inductively coupled plasma mass spectrometry, it was possible to correlate the size, morphology, and composition with the oxygen reduction reaction activities before and after accelerated stress tests. The octahedral catalysts show high electrochemical surface areas and increasing specific activity with increasing surface area of the (111) facets and Ni content, leading to high mass activities. These results demonstrate the advantages of increasing the (111) surface area and Ni content of PtNi nano-octahedral catalysts to improve the performance and stability for the oxygen reduction reaction.