Deposition of platinum on the outer surface of carbon-encapsulated silver nanoparticles

Investigations of the morphological and phase characteristics of silver nanoparticles encapsulated in amorphous carbon shell (Ag@C) during heating, acid treatment and galvanic replacement reactions were carried out. It was found that upon heating of Ag@C nanoparticles up to 800 °C the silver sublimes resulting in the formation of hollow carbon nanocapsules. Washing of Ag@C nanoparticles with nitric or hydrochloric acid solutions also leads to dissolution of encapsulated silver core and formation of hollow carbon nanocapsules. Electron microscopic investigations showed that, for short treatment times of Ag@C nanoparticles with a H2PtCl6 solution, nanoparticles of metallic platinum, several nanometers in diameter, are deposited on the outer surface of the carbon shells. With increasing treatment time or concentration of H2PtCl6 solution, increasing numbers of noble metal nanoparticles on the surface of the carbon shells, and almost complete dissolution of the metal core, were observed. This process opens broad possibilities for the design and direct preparation of modified by noble metal carbon-based nanomaterials of different compositions for a wide variety of practical applications.