Facile antisolvent crystallization synthesis of small Cu–Au alloy nanoparticles at room temperature

Metal nanoparticles (NPs) are typically synthesized via crystallization by exploiting the difference in the solution solubilities of the metal ions (precursors) and the metal atoms (monomers) that are formed during reduction reactions. However, in this method, it is difficult to control the size and composition of the NPs, as the rate of the reduction reactions of the precursors into monomers affects the supersaturation, which is the greatest variable in crystallization. In this study, antisolvent crystallization was used to separate the reduction reaction and crystallization processes in the synthesis of metal alloy NPs. Salt NPs of Cu and Au precursors were first synthesized by adding ethanol as an antisolvent to an aqueous solution of Cu and Au precursors and stabilizers. Then, Cu–Au alloy NPs were synthesized via the reduction of the salt NPs. Overall, this new antisolvent-based synthesis is facile and the composition of the synthesized NPs can be well controlled.