Size-Controlled Synthesis of Sub-10 nm PtNi3 Alloy Nanoparticles and their Unusual Volcano-Shaped Size Effect on ORR Electrocatalysis
Size-Controlled Synthesis of Sub-10 nm PtNi3 Alloy Nanoparticles and their Unusual Volcano-Shaped Size Effect on ORR Electrocatalysis
复制标题
亚 10 nm PtNi3 合金纳米颗粒的尺寸控制合成及其对 ORR 电催化的异常火山形尺寸效应
DOI：
10.1002/smll.201600027
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发表时间：
2016-06-15
期刊：
影响因子：
13.3
通讯作者：
Strasser, Peter
中科院分区：
文献类型：
--
作者：
Gan, Lin;Rudi, Stefan;Strasser, Peter
低铂双金属纳米粒子(如PtNi3)制备的非合金铂双金属核壳催化剂最近在实际燃料电池条件下的阴极氧还原反应(ORR)中表现出前所未有的活性和稳定性，成为当今汽车燃料电池商业化的首选催化剂。实现这一突破的一个关键步骤是将它们的粒度控制在一个临界值以下(大约10 nm)，以抑制纳米孔的形成，从而减少在腐蚀性ORR条件下显著的贱金属(如镍)的浸出。对小于10 nm的PtNi3纳米粒子进行精细的尺寸控制和了解其尺寸依赖的ORR电催化性能对于进一步提高其ORR活性和稳定性是至关重要的，但仍有待探索。本文提出了一种稳健的合成方法，在保持粒子组成不变的情况下，将PtNi3纳米粒子的尺寸控制在3~10 nm之间，并对其尺寸选择生长机理进行了全面的研究。这使我们能够第一次解决它们与大小相关的ORR活性和稳定性。与之前建立的在铂和富铂双金属纳米颗粒上ORR比活性和稳定性随着颗粒尺寸的增加而单调增加相反，缺乏铂的PtNi3纳米颗粒表现出不同寻常的火山形状的尺寸依赖关系，由于其在催化剂长期老化期间最高的镍保留率，在6-8 nm之间的颗粒尺寸范围内表现出最高的ORR活性和稳定性。本研究结果为进一步提高持久高活性的低铂双金属ORR电催化剂的粒度选择提供了重要的实用指导。
Dealloyed Pt bimetallic core-shell catalysts derived from low-Pt bimetallic alloy nanoparticles (e.g, PtNi3) have recently shown unprecedented activity and stability on the cathodic oxygen reduction reaction (ORR) under realistic fuel cell conditions and become today's catalyst of choice for commercialization of automobile fuel cells. A critical step toward this breakthrough is to control their particle size below a critical value (approximate to 10 nm) to suppress nanoporosity formation and hence reduce signifi cant base metal (e.g., Ni) leaching under the corrosive ORR condition. Fine size control of the sub-10 nm PtNi3 nanoparticles and understanding their size dependent ORR electrocatalysis are crucial to further improve their ORR activity and stability yet still remain unexplored. A robust synthetic approach is presented here for size-controlled PtNi3 nanoparticles between 3 and 10 nm while keeping a constant particle composition and their size-selected growth mechanism is studied comprehensively. This enables us to address their size-dependent ORR activities and stabilities for the first time. Contrary to the previously established monotonic increase of ORR specific activity and stability with increasing particle size on Pt and Pt-rich bimetallic nanoparticles, the Pt-poor PtNi3 nanoparticles exhibit an unusual "volcano-shaped" size dependence, showing the highest ORR activity and stability at the particle sizes between 6 and 8 nm due to their highest Ni retention during long-term catalyst aging. The results of this study provide important practical guidelines for the size selection of the low Pt bimetallic ORR electrocatalysts with further improved durably high activity.