The direct conversion of bulk silver metal to size-tailored bimetallic silver–gold (Ag/Au) nano-spheres and nano-chains with controllable compositions has been achieved by laser ablation of an Ag target in HAuCl4 solution. Taking advantage of the replacement reaction between Ag and Au ions, the average sizes of the bimetallic Ag/Au nano-particles substantially decreased from tens of nanometers to sub-2 nm with the increase in HAuCl4 concentration (0.12–4.59 mM). Meanwhile, the relative ratio of Ag and Au elements in individual Ag/Au nano-particles has been systematically changed from about 9 : 1 to 1 : 9. The UV-visible absorption spectra of the Ag/Au nano-particles significantly red shifted from about 400 nm to 785 nm. The designed simplistic, single-step, versatile strategy does not require seed preparations, intermediate workup processes or any potential toxic surfactants. This will offer a convenient and valuable new way to fabricate bimetallic nano-particles with desired structures and functions.
