Sonochemical design of engineered gold-silver nanoparticles

The sonochemical technique includes the application of ultrasound (20 kHz, 500 W) to a medium as a pressure wave resulting in cavitation in it. The implosive collapse of vapor microbubbles (cavities) creates shock waves with extremely high physical forces for modification of gold nanoparticles. Stable monodisperse gold nanoparticles with a diameter of 30 nm produced by the titration method were used as initial templates These formed gold nanoparticles mixed with the surfactants (sodium borohydride in water; poly(vinyl. pyrrolidone) in ethylene glycol; poly(ethylene glycol); sodium dodecyl sulfate in water or propanol) were added into the pre-sonicated silver solution and then were sonicated again. Transmission electron microscopy, electron and wide-angle X-ray diffraction accompanied with UV-vis absorption spectroscopy data revealed that only 10 min of ultrasonic irradiation was enough to form monodisperse polygonal gold-silver structures. More than 1 h of ultrasonic treatment was required to create gold-silver worms or netlike nanostructures capped with sodium dodecyl sulfate. Gold-silver nanocomposites produced in presence of any surfactant dramatically increased their size. The most, pronounced effect of this increase was noticed for worm- or netlike gold-silver nanocomposites fabricated in the presence of sodium dodecyl sulfate either in propanol or in water.