Effect of Metal Concentration on Shape and Composition Changes in Gold-Silver Bimetallic Systems

Ag-Au alloy nanoparticles with tunable shape and composition were prepared by a replacement reaction between Ag nanoparticles and chloroauric acid at one hundred and fifty degree celsius temperature under oilbath heating. The replacement reaction between silver nanostructures and chloroauric acid solution has recently been demonstrated as a versatile method for generating Au-Ag alloy nanostructures via galvanic reaction. Here we describe the results of a systematic study detailing the morphological, structural, compositional involved in such a heterogeneous reaction on the nanoscale. This method leverages upon the rapid interdiffusion of Ag and Au atoms in the reduced dimension of a nanoparticle in the replacement reaction. This method of preparation has several notable advantages: (1) independent tuning of the shape, size and composition of alloy nanoparticles; (2) production of alloy nanoparticles in high concentrations; (3) general utility in the synthesis of alloy nanoparticles that cannot be obtained by the co-reduction method.