Thermal Synthesis of Silver Nanoplates Revisited: A Modified Photochemical Process

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• 作者：Hongxia Yu ; Qiao Zhang ; Hongyan Liu ; Michael Dahl ; Ji Bong Joo ; Na Li ; Lianjun Wang ; Yadong Yin
• 刊名：ACS Nano
• 出版年：2014
• 出版时间：October 28, 2014
• 年：2014
• 卷：8
• 期：10
• 页码：10252-10261
• 全文大小：597K
• ISSN：1936-086X

文摘

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 Ag⁰ 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.

Keywords:

silver; nanoplates; photochemical synthesis; thermal synthesis; H₂O₂