Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH, 44325, USA.
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
Nat Commun. 2018 Oct 26;9(1):4485. doi: 10.1038/s41467-018-06900-z.
Understanding the growth pathway of faceted alloy nanoparticles at the atomic level is crucial to morphology control and property tuning. Yet, it remains a challenge due to complexity of the growth process and technical limits of modern characterization tools. We report a combinational use of multiple cutting-edge in situ techniques to study the growth process of octahedral PtNi nanoparticles, which reveal the particle growth and facet formation mechanisms. Our studies confirm the formation of octahedral PtNi initiates from Pt nuclei generation, which is followed by continuous Pt reduction that simultaneously catalyzes Ni reduction, resulting in mixed alloy formation with moderate elemental segregation. Carbon monoxide molecules serve as a facet formation modulator and induce Ni segregation to the surface, which inhibits the (111) facet growth and causes the particle shape to evolve from a spherical cluster to an octahedron as the (001) facet continues to grow.
了解面心立方合金纳米粒子在原子水平上的生长途径对于形貌控制和性能调优至关重要。然而，由于生长过程的复杂性和现代表征工具的技术限制，这仍然是一个挑战。我们报告了多种尖端原位技术的组合使用，以研究八面体 PtNi 纳米粒子的生长过程，揭示了颗粒生长和晶面形成的机制。我们的研究证实，八面体 PtNi 的形成始于 Pt 核的生成，随后是连续的 Pt 还原，同时催化 Ni 的还原，导致具有适度元素偏析的混合合金形成。一氧化碳分子作为晶面形成调节剂，诱导 Ni 向表面偏析，从而抑制（111）晶面的生长，并导致颗粒形状从球形团簇演变为八面体，同时（001）晶面继续生长。
