Evidence for the Growth Mechanisms of Silver Nanocubes and Nanowires

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• 作者：Sujie Chang ; Kai Chen ; Qing Hua ; Yunsheng Ma ; Weixin Huang
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：April 28, 2011
• 年：2011
• 卷：115
• 期：16
• 页码：7979-7986
• 全文大小：1168K
• 年卷期：v.115,no.16(April 28, 2011)
• ISSN：1932-7455

文摘

Ethylene glycol reduction of silver nitrate at 140 掳C in the presence of poly(vinyl pyrrolidone) (PVP) and HCl is a facile method to prepare uniform silver nanocubes (Im et al., Angew. Chem., Int. Ed.2005, 44, 2154). We reported herein that the product switches from uniform silver nanocubes to uniform silver nanowires by simply aging the freshly prepared AgNO₃ solution under ambient atmosphere for 5 min without the change of any other reaction parameters. The aging process was found to increase the density of silver seeds and, more importantly, to change the population of single and twinned crystal seeds. The portion of twinned-crystal seeds is less than 30% of total silver seeds in the freshly prepared AgNO₃ solution but more than 60% of total silver seeds in the AgNO₃ solution aged for 5 min. We proposed that twinned-crystal silver seeds in the freshly prepared AgNO₃ solution can be adequately etched in the subsequent etching and growth process, leading to the growth of silver nanocubes, but that those in the AgNO₃ solution aged for 5 min can not, leading to the growth of silver nanowires. Twinned-crystal silver seeds in the AgNO₃ solution aged for 5 min could be effectively etched by the increase of the concentration of HCl, yielding uniform silver nanocubes again. These results unambiguously prove the important role of twinned-crystal seeds in the growth of anisotropic silver metal nanowires and also indicate that the morphology of silver nanostructures prepared by the polyol process in the presence of PVP can be tuned by controlling the interplay between the population of twinned-crystal silver seeds and the concentration of HCl, greatly deepening the fundamental understanding of the growth mechanisms of silver nanocubes and nanowires.