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NM05.11.04 : Facile Synthesis of Silver Nanocubes with Sharp Corners and Edges in an Aqueous Solution

5:00 PM–7:00 PM Apr 5, 2018

PCC North, 300 Level, Exhibit Hall C-E

Description
Shan Zhou1 Jianhua Li2 Kyle Gilroy2 Jing Tao3 Chunlei Zhu2 Xuan Yang2 Xiaojun Sun4 Younan Xia1 2

1, Georgia Institute of Technology, Atlanta, Georgia, United States
2, Georgia Institute of Technology, Atlanta, Georgia, United States
3, Brookhaven National Laboratory, Upton, New York, United States
4, Georgia Institute of Technology, Atlanta, Georgia, United States

It remains a challenge to synthesize Ag nanocubes in an aqueous system, although the polyol process was successfully adopted more than one decade ago. Here, we report an aqueous method for the synthesis of Ag nanocubes with an average edge length of 35–95 nm. It involves the formation of AgCl octahedra by mixing CF3COOAg with cetyltrimethylammonium chloride, followed by the nucleation and growth of Ag nanocrystals in the presence of ascorbic acid (AA) and FeCl3. The Fe3+/Fe2+ redox pair is responsible for the removal of multiply twinned seeds through oxidative etching. The Cl ions play two critical roles in the nucleation and growth of Ag nanocubes with a single-crystal structure. First, the Cl ions react with Ag+ ions to generate nanometer-sized AgCl octahedra in the initial stage of a synthesis. In the presence of room light and a proper reducing agent such as AA, the AgCl can be reduced to generate Agn nuclei followed by their evolution into single-crystal seeds and then Ag nanocrystals. Second, the Clions can act as a specific capping agent toward the Ag(100) surface, enabling the formation of Ag nanocubes with sharp corners and edges. Based on the results from a set of time-lapse studies and control experiments, we formulate a plausible mechanism to account for the formation of Ag nanocubes that resembles the formation and development of latent image centers in silver halide grains in the photographic process. In addition to the demonstration of a greener and economically more favorable method than the polyol process, this work also offers insights into the design of aqueous protocols for the synthesis of silver nanocrystals with controlled shapes.

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