Shape Transformation via Etching and Regrowth: A Systematic Study of Pd Nanocrystals with Different Shapes and Twin Structures
Shape Transformation via Etching and Regrowth: A Systematic Study of Pd Nanocrystals with Different Shapes and Twin Structures
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通过蚀刻和再生进行形状转变：不同形状和孪晶结构的 Pd 纳米晶体的系统研究
DOI：
10.1002/chem.202301465
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Xia, Younan
中科院分区：
文献类型：
--
作者：
Lv, Tian;Liu, Maochang;Zhou, Siyu;Xia, Younan
本文介绍了 Pd 纳米晶体的氧化蚀刻和再生长行为的系统研究，包括由 {100} 面包围的单晶立方体、由 {111} 面包围的单晶八面体和四面体；以及被{111}面和孪晶边界覆盖的多重孪生二十面体。在蚀刻过程中，无论纳米晶体的类型如何，Pd原子都会优先被氧化并从角落去除，然后所得的Pd2+离子被还原回元素Pd。对于立方体和二十面体，由于能量相对较高，新形成的 Pd 原子分别沉积在 {100} 面和孪晶边界上。对于八面体和四面体，Pd 原子在溶液相中自成核，然后生长成小颗粒。我们可以通过改变反应溶液中 HCl 的浓度来控制相对于蚀刻速率的再生长速率。随着 HCl 浓度的增加，18 nm 的 Pd 立方体转变为边长分别为 23、18 和 13 nm 的八面体。然而，由于没有再生长，Pd 八面体转变为截角八面体、立方八面体和尺寸减小的球体，而 Pd 四面体则演化为截角四面体和球体。相比之下，表面具有孪生边界的 Pd 二十面体将转化为不对称二十面体、花状二十面体和球体。这项工作不仅增进了对各种形状和孪生结构金属纳米晶体的蚀刻和生长行为的理解，而且还提供了控制其形状和尺寸的替代方法。
This article describes a systematic study of the oxidative etching and regrowth behaviors of Pd nanocrystals, including single‐crystal cubes bounded by {100} facets, single‐crystal octahedra and tetrahedra enclosed by {111} facets; and multiple‐twinned icosahedra covered by {111} facets and twin boundaries. During etching, Pd atoms are preferentially oxidized and removed from the corners regardless of the type of nanocrystal, and the resultant Pd2+ions are then reduced back to elemental Pd. For cubes and icosahedra, the newly formed Pd atoms are deposited on the {100} facets and twin boundaries, respectively, due to their relatively higher energies. For octahedra and tetrahedra, the Pd atoms self‐nucleate in the solution phase, followed by their growth into small particles. We can control the regrowth rate relative to etching rate by varying the concentration of HCl in the reaction solution. As the concentration of HCl is increased, 18‐nm Pd cubes are transformed into octahedra of 23, 18, and 13 nm, respectively, in edge length. Due to the absence of regrowth, however, Pd octahedra are transformed into truncated octahedra, cuboctahedra, and spheres with decreasing sizes whereas Pd tetrahedra evolve into truncated tetrahedra and spheres. In contrast, Pd icosahedra with twin boundaries on the surface are converted to asymmetric icosahedra, flower‐like icosahedra, and spheres. This work not only advances the understanding of etching and growth behaviors of metal nanocrystals with various shapes and twin structures but also offers an alternative method for controlling their shape and size.