Sonochemical synthesis and characterization of gold–ruthenium bimetallic nanoparticles

Gold–ruthenium (Au–Ru) bimetallic nanoparticles were synthesized by the sonochemical co-reduction of Au(III) and Ru(III) ions in aqueous solutions containing varying mole fractions (1:1, 1:3 and 1:5) of the metal ions using PEG as a stabilizer. The results observed in the current study suggest that the presence of Au nanoparticles significantly reduced the time required from 7 h to 4 h for Ru3+ reduction due to the Au nanoparticles acting as electron sink mediating the Ru3+ reduction process. Transmission electron microscopic images revealed that the bimetallic nanoparticles were formed with higher ruthenium content in the shell and higher gold content in the core. The mean diameter of Au–Ru bimetallic nanoparticles increased with an increase in the molar ratio of Ru. A decrease in the double layer current was observed when a Au–Ru bimetallic nanoparticles modified electrode was used in electrochemical experiments compared to a Ru-modified electrode, indicating the potential use of these bimetallic nanoparticles in methanol oxidation fuel cells.