Probing the seeded protocol for high-concentration preparation of silver nanowires

Mass production of high-quality silver nanowires (Ag NWs) is of significant importance because of its potential applications in flexible transparent conductive devices. Halogen ions have been widely used for the synthesis of Ag NWs; however, owing to the lack of a deep insight into heterogeneous nucleation processes, usually a trace feeding amount (e.g. [Cl^–] < 0.25 mM) is used, which in turn lowers the concentration of precursor ([Ag⁺]). Here we systematically investigated the nucleation and growth behavior of Ag NWs and concluded that the number of heterogeneous nucleation sites was determined by the total surface area of AgCl seeds, which indicated a linear relationship between the concentrations of Ag⁺ and Cl^– during precipitation. Based on this mechanism, we successfully produced high-quality Ag NWs with Ag⁺ concentrations which were 20 times higher for a polyol system and 5 times higher for an aqueous system as compared to that in the previously reported strategies. Besides, by tailoring the heterogeneous nucleation sites by controlling the size of the AgCl seeds, the diameters of the final Ag NWs could be well controlled even at high Ag⁺ concentration. Based on the mechanistic understandings, this synthetic strategy could be extended to other AgX-seeds (X = Br^–, I^– and SO₄^2–) and the basic principles can be applied to help rational synthesis of other high-yield metal NWs with tunable sizes.