Synthesis of Marks-Decahedral Pd Nanoparticles in Aqueous Solutions
Synthesis of Marks-Decahedral Pd Nanoparticles in Aqueous Solutions
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水溶液中Marks-十面体钯纳米粒子的合成
DOI：
10.1002/ppsc.201400003
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发表时间：
2014
影响因子：
2.7
通讯作者：
Y. Pang
中科院分区：
文献类型：
--
作者：
W. H. Ji;W. H. Qi;S. S. Tang;B. Y. Huang;M. P. Wang;Y. Li;Y. L. Jia;Y. Pang
由于其表面能、内部晶体应变和晶格对称性等特殊的内在结构特征，多孪晶颗粒（MTPs）可能表现出与非孪晶纳米颗粒不同的物理和化学性质。其中，十面体和二十面体的MTPs，包括Ag， Au, Fe， Pd和Pt-Pd，以可控的形状合成。[1-5]利用高分辨率电子显微镜研究了十面体纳米颗粒的结构，并通过理论模型阐明了它们的热力学稳定性十面体是具有D5h对称的最紧凑的五边形环状孪晶形状。一般来说，经典的十面体（图1a）由五个具有面心立方（FCC）晶体结构的四面体亚基组成，并由{111}晶面封闭。除了共享一条与五重轴重合的边外，子单元还通过双边界连接最近的邻居。催化裂化金属的表面能大小为γ {111}< γ {100}< γ{110}。最稳定的十面体结构是Marks十面体（图1b），[8]，而新增加的平面平行于十面体单元的孪生{111}，以降低表面能，忽略应变。除了尺寸，纳米颗粒的性质也取决于它们的形状。[9-12]因此，控制纳米颗粒的形态对研究和应用至关重要。大多数形状控制合成涉及有机金属化合物的热分解或在有机表面活性剂、聚合物、生物大分子等的帮助下还原盐前体。聚合物作为空间稳定剂或封盖剂广泛应用于胶体纳米颗粒的化学合成。特别是聚乙烯醇吡咯烷酮（PVP）因其化学稳定性高、无毒、在许多极性溶剂中的溶解性好而受到特别关注。这种独特的多功能和强大的化学物质已被用作各种合成的表面活性剂或稳定剂
Multiple twinned particles (MTPs) may exhibit physical and chemical properties differing from those of untwined nanoparticles because of their special intrinsic structural characteristics concerning surface energy, internal crystal strain, and the lattice symmetry. Of these, decahedral and icosahedral MTPs, including Ag, Au, Fe, Pd, and Pt–Pd, are synthesized with controlled shapes.[1–5] The structure of decahedral nanoparticles had been studied by high-resolution electron microscopy,[6] and their thermodynamic stability has been elucidated by theoretical modeling.[7] Decahedrons are the most compact pentagonal cyclic twinning shape with D5h symmetry. In general, the classic decahedron (Figure 1a) is composed of five tetrahedral subunits with the face-centered cubic (FCC) crystal structure and closed by {111} crystallographic faces. In addition to sharing one edge coinciding with the fivefold axis, subunits connect the nearest neighbors by twin boundaries. The surface energy of FCC metals follows the order of γ {111}< γ {100}< γ {110}. The most stable decahedral structure is the Marks decahedron (Figure 1 b),[8] while the new added planes are parallel to the decahedral units’ twinning {111} in order to reduce the surface energy, ignoring strain.In addition to size, the properties of nanoparticles also depend on their shapes.[9–12] Thus, controlling the morphology of nanoparticles is essential for researches and applications. Most of the shape-controlled syntheses involve the thermal decomposition of organometallic compounds or the reduction of salt precursors with the help of organic surfactants, polymers, biomacromolecules, etc. Polymers are widely used in the chemical synthesis of colloidal nanoparticles as steric stabilizers or capping agents. In particular, poly (vinyl pyrrolidone)(PVP) has received special attention due to its high chemical stability, non-toxicity, and excellent solubility in many polar solvents. This uniquely versatile and powerful chemical has been used as a surfactant or stabilizer in a wide variety of synthetic