Acetate Stabilization of Metal Nanoparticles and Its Role in the Preparation of Metal Nanoparticles in Ethylene Glycol

Acetate-stabilized ruthenium nanoparticles were prepared by the NaBH₄ reduction of the metal precursor salt at room temperature. Nanoparticles with a mean diameter of 2.20 nm and a standard deviation of 1.03 nm could be obtained under experimental conditions. The Ru nanoparticles so obtained could be easily extracted to a toluene solution of alkylamine, giving rise to alkylamine-stabilized Ru nanoparticles with a mean diameter of 2.96 nm and a standard deviation of 0.92 nm. The new found role of acetate stabilization was used to formulate a mechanism for the formation of metal (Pt, Ru) nanoparticles in ethylene glycol. In this mechanism metal nanoparticles are stabilized in ethylene glycol by adsorbed acetate ions, which are produced as a product of the OH^- catalyzed reaction between the metal precursor salt and ethylene glycol.