Sonochemical preparation of single-dispersion metal nanoparticles from metal salts

Novel metal nanoparticles of Pd and Pt were prepared by sonochemical reduction of solutions containing H2PtCl6 or K2PdCl4. The effect of atmospheric gas on the particle size distribution was investigated. Average diameters and standard deviations of the Pd particles prepared under Ar (Pd/Ar) and N-2 (Pd/N-2) were found to be 3.6 +/- 0.7 nm (Pd/Ar) and 2.0 +/- 0.3 nm (Pd/N-2). Smaller and sharper distribution of the particle size was observed for the Pd particles formed under a Na atmosphere. In the case of Pt, a smaller and sharper distribution of the particle size was observed for the particles prepared under a Xe atmosphere. These relations can be explained in terms of a hot-spot temperature created by acoustic cavitation.