Fabrication of catalytically active AgAu bimetallic nanoparticles by physical mixture of small Au clusters with Ag ions

Catalytically highly active PVP-protected AgAu bimetallic nanoparticles (BNPs) less than 2 nm in diameter were fabricated by simultaneous physical mixture of aqueous dispersions of Au clusters with Ag+ ions. The prepared AgAu BNPs, the dispersion of which was stably kept for more than 2 months under ambient conditions, were characterized by UV–vis, ICP, HR-TEM, and EDS in HR-STEM. The prepared BNP colloidal catalysts possessed a high activity for aerobic glucose oxidation. The highest activity of 3.77 mol-glucose s−1 mol-metal−1 was observed for the BNPs prepared with Ag/Au atomic ratio of 2/8, which was more than two times higher than that of Au nanoparticles with nearly the same particle sizes.

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► Highly active and durable AgAu bimetallic nanoparticles were prepared.
► About one third of the bimetallic nanoparticles could have a Ag-core/Au-shell structure.
► Mixture of Au nanoparticles and AgClO4 provided the small nanoparticles (d < 2.0 nm).
► This is the first example of small AgAu bimetallic nanoparticles by physical mixture.
► The nanoparticles had twice catalytic activity of Au nanoparticles with same size.