Sonochemical preparation of noble metal nanoparticles in the presence of various surfactants

Noble metal particles were prepared by the sonochemical reduction of noble metal ions, NaAuCl₄ (Au (III)), PdCl₂ (Pd (II)), H₂PtCl₆ (Pt (IV)) and K₂PtCl₄ (Pt (II)) in the aqueous solution containing surfactants, such as sodium dodecylsulfate (SDS), sodium dodecylbenzensulfonate (DBS) and polyethylene glycol monostearate (PEG-MS). The sonochemical reduction rates of Au (III) to Au (0), Pd (II) to Pd (0), Pt (IV) to Pt (II) and Pt (II) to Pt (0) in SDS solution (CMC; 8 mM) are 83, 140, 97 and 24 μM/min, respectively. The size of metal nanoparticles were measured by TEM, in the case of SDS solution, the particles of Au, Pt and Pd are 13 nm, 3 nm and 7 nm in diameter with narrow distribution. The reduction rates in PEG-MS (Au (III) to Au (0); 380 μM/min, Pd (II) to Pd (0); 330 μM/min, Pt (IV) to Pt (II);150 μM/min) were faster than those in SDS and the size of nanoparticles of Pd (4 nm) in PEG-MS was smaller than that in SDS. The size of the particles in the growing process became feasible to be measured by removing coexisting ions at each desired time by means of anion-exchange resin.