Novel Synthesis, Structure, and Oxidation Catalysis of Ag/Au Bimetallic Nanoparticles

The surface plasmon resonance peak due to Au nanoparticles dramatically increased after addition of AgClO4 into an aqueous dispersion of Au nanoparticles without appearance of Ag plasmon absorbance near 400 nm. The addition of AgClO4 into aqueous dispersions of Au nanoparticles has been found to produce bimetallic silver-gold nanoparticles with a core-shell type structure. The Ag-core/Au-shell type configuration was suggested by the data from energy dispersive X-ray spectra of prepared nanoparticles on a high-resolution electron microscope. Moreover, the catalytic activity for glucose oxidation was investigated for thus-prepared Ag/Au bimetallic nanoparticles with various compositions. The highest activity (4079 mol-glucose h(-1) mol-M-1) was observed for the Ag/Au nanoparticle prepared with Ag/Au ratio of 0.25/1, the activity being 18 times higher than that of original monometallic Au nanoparticles under the same conditions.