The synthesis of Pt/Ag bimetallic nanoparticles using a successive solution plasma process.

A successive solution plasma process was developed for the synthesis of Pt/Ag bimetallic nanoparticles. Ag nanoparticles were made first by applying a high voltage of bipolar pulsed DC to anode and cathode electrodes composed of Ag rods. The solution containing Ag nanoparticles was discharged successively using Pt electrodes. The joule heating and electrolysis between electrodes generated vapors, and solution plasma was sustained due to progressive ionization and excitation in the vapor phase. The maximum current and voltage breakdown was observed at approximately 8.9 A and 900 V with an interval of 25 μs, which indicated that an intense solution plasma was sustained continuously. The Pt-on-Ag heterogeneous nanostructures formed, and finally, the Ag nanoparticles were completely covered by Pt nanoparticles after a discharge duration of 1,200 s.