One-step synthesis of Au-Ag alloy nanoparticles by a convenient electrochemical method

Gold-silver alloy nanoparticles with various mole ratios were synthesized in aqueous solution by an electrochemical co-reduction of chloroauric acid (HAUCl(4)) and silver nitrate (AgNO(3)) in the presence of poly(vinyl-pyrrolidone) (PVP) used as a protecting agent. The UV-visible absorption spectra of the bimetallic systems and the physical mixtures of individual metallic nanoparticles suggested the formation of alloy nanoparticles. The absorption maximum of the plasmon band shifts linearly to the red with increasing Au content. The size distribution of the alloy nanoparticles was examined using transmission electron microscopy. The EDX analysis on individual particles confirmed the presence of two metals in a particle. The X-ray diffraction also confirmed the formation of homogeneous gold-silver nanostructure. The effects of the preparation conditions including the concentration of polymer stabilizer (PVP), the molar ratio of HAuCl(4) and AgNO(3) and reaction time were investigated. Also, the formation process for bimetallic nanoparticles was discussed. (c) 2006 Elsevier B.V. All rights reserved.