Polyol Syntheses of Palladium Decahedra and Icosahedra as Pure Samples by Maneuvering the Reaction Kinetics with Additives
Polyol Syntheses of Palladium Decahedra and Icosahedra as Pure Samples by Maneuvering the Reaction Kinetics with Additives
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DOI：
10.1021/nn501919e
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发表时间：
2014-07-01
期刊：
影响因子：
17.1
通讯作者：
Xia, Younan
中科院分区：
文献类型：
--
作者：
Huang, Hongwen;Wang, Yi;Xia, Younan
本文报道了一种基于多元醇还原的确定性合成Pd十面体或二十面体的方法，其大小可调，纯度接近100%。这种选择性合成的成功依赖于通过分别为十面体和二十面体添加Na-2-SO4和Ha来微调反应动力学的能力。在没有任何添加剂的情况下，在二甘醇中类似合成的产物含有10%的十面体和90%的二十面体。通过优化反应溶液中Na2SO4（或HCI）的加入量，可使产物中十面体（或二十面体）的含量达到100%。对Na2SO4和Ha的作用也进行了详细的研究，提出了两种可能的机制，并通过一系列实验进行了验证。一般来说，合成十面体钯所需的还原速率比合成二十面体钯所需的还原速率要快。这项工作不仅为钯十面体和二十面体的确定性合成提供了一种简单的方法，而且从反应动力学的角度深入了解了贵金属纳米晶体形状控制合成的机制。在机理了解的基础上，我们还通过在体系中加入适量的NaOH加速还原动力学，成功地合成了Pd十面体的纯样品。
This article reports a robust method based upon polyol reduction for the deterministic synthesis of Pd decahedra or Icosahedra with tunable sizes and a purity approaching 100%. The success of such a selective synthesis relies on an ability to fine-tune the reaction kinetics through the addition of Na-2-SO4 and Ha for decahedra and icosahedra, respectively. In the absence of any additive, the product of a similar synthesis in diethylene glycol contained 10% decahedra and 90% icosahedra. By optimizing the amount of Na2SO4 (or HCI) added into the reaction solution, the percent of decahedra (or icosahedra) in the product could be Increased up to 100%. The roles of Na2SO4 and Ha were also investigated in great detail, and two plausible mechanisms were proposed and validated through a set of experiments. In general, a faster reduction rate is needed for the synthesis of Pd decahedra when compared with what is needed for Pd icosahedra. This work not only offers a simple approach to the deterministic syntheses of Pd decahedra and icosahedra but also provides an in-depth understanding of the mechanisms involved in shape-controlled syntheses of noble-metal nanocrystals from the perspective of reaction kinetics. On the basis of the mechanistic understanding, we have also achieved successful synthesis of Pd decahedra as pure samples by adding a proper amount of NaOH into the system to speed up the reduction kinetics.