Thermal synthesis of silver nanoplates revisited: a modified photochemical process.
Thermal synthesis of silver nanoplates revisited: a modified photochemical process.
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DOI：
10.1021/nn503459q
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发表时间：
2014-09
期刊：
影响因子：
17.1
通讯作者：
Hongxia Yu;Qiao Zhang;Hongyang Liu;Michael Dahl;J. Joo;Na Li;Lianjun Wang;Yadong Yin
中科院分区：
文献类型：
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作者：
Hongxia Yu;Qiao Zhang;Hongyang Liu;Michael Dahl;J. Joo;Na Li;Lianjun Wang;Yadong Yin
众所周知的光化学和热合成银纳米板的方法通常被认为是两个平行的过程，没有很强的联系。在这里，我们报告了一个令人惊讶的发现，可见光和环境O2在光化学过程中至关重要，也在热合成中起决定性作用。通过设计一系列的对照实验，我们揭示了典型的热合成本质上是一种修饰的光化学合成，加上H2O2独特的氧化还原性质。光照射和溶解的O2对于纳米板的形成至关重要，但是氧化蚀刻和随后的H2O2对Ag的还原支持了纳米板的持续生长。H2O2催化分解产生的O2蚀刻小纳米颗粒产生Ag（+）离子，然后被H2O2的阴离子还原回Ag(0)，以支持纳米板种子的生长。H2O2的加入大大加快了纳米板的形成过程。这些发现不仅大大提高了我们对H2O2在热合成中的独特功能的认识，而且通过确定环境光和O2的关键重要性，为两种成熟的合成工艺建立了统一的机制桥梁，并显著提高了银纳米片热合成的可重复性。
The well-known photochemical and thermal methods for silver nanoplate synthesis have been generally regarded as two parallel processes without strong connections. Here we report a surprising finding that both visible light and ambient O2, which are critically important in the photochemical process, also play determining roles in the thermal synthesis. By designing a series of control experiments, we reveal that the typical thermal synthesis is essentially a modified photochemical synthesis coupled with the unique redox properties of H2O2. Light irradiation and dissolved O2 are found to be essential for initiating the formation of nanoplates, but the continued growth of nanoplates is supported by the oxidative etching and subsequent reduction of Ag due to H2O2. O2 resulting from the catalytic decomposition of H2O2 etches small nanoparticles to produce Ag(+) ions, which are then reduced back to Ag(0) by anions of H2O2 to support the growth of nanoplate seeds. The involvement of H2O2 in the reaction significantly speeds up the nanoplate formation process. These findings not only greatly improve our understanding of the unique functions of H2O2 in the thermal synthesis, but also bridge the two well established synthesis processes with a unified mechanism, and significantly enhance the reproducibility of the thermal synthesis of Ag nanoplates by identifying the critical importance of ambient light and O2.