Ultrasonic effect on the morphology and activity of metal nanoparticles

ULTRASONIC EFFECT ON THE MORPHOLOGY AND ACTIVITY OF METAL NANOPARTICLES 

Max-Planck Institute of Colloids and Interfaces, Interfaces Department D14424 Potsdam, Germany 

Preformed gold or platinum nanoparticles were ultrasonically treated under argon flow in a home-developed sonoreactor at a constant temperature. Bare gold nanoparticles lose crystallinity in water after 45 min of sonication. Ultrasonic treatment for 20 min in water revealed piorphous platinum nanoparticles with similar catalytic efficiency. The fastest catalysis was accomplished by platinum nanoparticles formed after sonication in an ethylene glycol solution for 20 min, hile the lowest one was enabled by platinum nanoparticles after one hour of ultrasonic treatment in presence of poly vinyl pyrrolidone. 

Gold received much attention due to their unique size-dependent optical properties, insolubility in nitric acid and resistance to heat, moisture, oxygen and most corrosive reagents. For substrates in surface-enhanced Raman Spectroscopy (SERS), ergonomic electronic contacts, ultra fast data communication and biomedicine surface modified gold nanoparticles are perspective agents, while in the industry of catalysis platinum nanoparticles (Pt NPs) exhibiting excellent anticorrosive and catalytic properties are usually employed. 

The present report pursues the following goals i) to illuminate the effect of ultrasonic treatment on the crystal structure of preformed gold and platinum nanoparticles ii) to investigate the catalytic efficiency of platinum nanoparticles ultrasonically treated in ethylene glycol (EG) or poly vinyl pyrrolidone (PVP) solutions. For reproducible ultrasonic experiments a home-developed ultrasonic 

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