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Application Note: Synthesis of Silver Nanowires

By: Kaushik Patel, Material Matters Volume 4 Article 1

Uniform Ag nanowires can be readily synthesized using a modified polyol process. A typical synthesis involves ethyleneglycol (EG) (Aldrich Prod. No. 324558) as both the solvent and the reducing agent, with AgNO 3(Aldrich Prod. No.204390) and poly(vinvlpyrrolidone) (PVP, MW=55000) (Aldrich Prod. No. 856568) as the Ag precursor and thepolymeric capping agent, respectively. In this synthesis, CuCl2(Aldrich Prod. No. 203149) species can be added tofacilitate the anisotropic growth of Ag nanowires. In a typical synthesis, 5 mL of EG was added to a disposable glassvial with a Teflon stir bar in it; the vial was then suspended in an oil bath (temperature = 151.5 oC) and heated for 1 hunder magnetic stirring (260 rpm). At 1 h, 40 L of a 4 mM CuCl2 solution in EG was injected into the heated EG. Thesolution was heated for an additional 15 min. 1.5 mL of a 0.147 M PVP solution in EG (concentration calculated interms of the repeating unit) was then injected into the heated EG, followed by the addition of 1.5 mL of a 0.094 MAgNO3solution in EG. The color of the reaction solution changed as follows: initially clear and colorless to yellow(within 1 min), to red-orange (within 3 min), to green, beginning cloudiness (within 5 min), to cloudiness, with a gradualshift from green to brown-red (within 30 min), and finally to opaque gray with wispiness indicating the formation of longnanowires (within 1 to 1.5 h). Upon formation of Ag nanowires, the reaction was quenched by cooling the reaction vialin a room temperature water bath. The products were washed with acetone once and water three times to removeexcess EG and PVP prior to characterization.

Figure 1. Experimental setup used to prepare Ag nanowires. (a) A photograph of the entire experimental setup. A temperature-controlled stirring hotplate is used, and the reaction is performed in a disposable glass vial suspended in an oil-containingcrystallization dish. (b) A photograph of the custom-made vial holder, designed to rest on top of the oil-containing crystallizationdish and hold up to eleven reaction vials. (c) A close-up photograph of the reaction vials. The reaction vials are supported by anO-ring and suspended in a heated oil bath. The caps are tiled off-angle during initial preheating to allow water vapor to escape.

Materials

Product Molecular Add to

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# Image Description Formula Cart

203149 Copper(II) chloride 99.999% trace metals basis Cl2Cu wycena

856568 Polyvinylpyrrolidone powder, average Mw

~55,000

wycena

204390 Silver nitrate 99.9999% trace metals basis AgNO3 wycena

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