十二面体
纳米颗粒
材料科学
四面体
化学物理
结晶学
对称性破坏
旋转对称性
纳米技术
纳米晶
化学
物理
机械
量子力学
作者
Muhua Sun,Zhihua Cheng,Wei-Yin Chen,Matthew R. Jones
出处
期刊:ACS Nano
[American Chemical Society]
日期:2021-09-23
卷期号:15 (10): 15953-15961
被引量:23
标识
DOI:10.1021/acsnano.1c04056
摘要
The vast majority of single crystalline metal nanoparticles adopt shapes in the Oh point group as a consequence of the symmetry of the underlying face-centered cubic (FCC) crystal lattice. Tetrahedra are a notable exception to this rule, and although they have been observed in several syntheses, their growth mechanism, and the symmetry-reduction process that necessarily characterizes it, is poorly understood. Here, a symmetry breaking mechanism is revealed by in situ liquid flow cell transmission electron microscopy (TEM) observation of seeded growth in which tetrahedra nanoparticles are formed from higher symmetry seeds. Real-time observation of the growth demonstrates a kinetically driven pathway during which rhombic dodecahedra nanoparticles transition to tetrahedra through tristetrahedra intermediates, with an accompanying surface facet evolution from {110} to {111} via {hhl} (where h > l), respectively. On the basis of these data, we propose a mechanism that relies on a rapid loss of inversion symmetry in the initial stages of the reaction, followed by differential reactivity of tips vs faces under conditions of relatively high supersaturation and moderate ligand concentration. The application of these insights to ex situ synthesis conditions allowed for an improved yield of tetrahedra nanoparticles. This work sheds an important mechanistic light on the crystallographic underpinnings of nanoparticle shape and symmetry transformations and highlights the importance of single-particle characterization tools for monitoring nanoscale phenomena.
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