Fabrication of metallic copper nanoparticles by utilizing a difference in standard electrode potential

The present work proposes a method for synthesizing metallic copper (Cu) nanoparticles in aqueous solution. An aqueous colloidal solution of metallic Cu nanoparticles was prepared from Cu acetate by deposition of metallic Cu on metallic zinc (Zn) plate based on the difference in standard electrode potentials between Cu and Zn under ultrasonic irradiation in water, in which the ultrasonic irradiation was performed to disperse the nanoparticles in water. In the absence of the stabilizer and in the presence of polyvinylpyrrolidone (PVP), Cu2O was produced, even though metallic Cu nanoparticles were obtained. In addition, the nanoparticles with sizes of 60–80 nm formed aggregates in the absence of a stabilizer, and the nanoparticles with a size of several hundred nanometers were produced with PVP. In contrast, when cetyltrimethylammonium bromide (CTAB) was used as a stabilizer, metallic Cu nanoparticles with an average particle size of 22.7 ± 11.5 nm and a crystal size of 20.1 nm were fabricated, and no Cu2O was produced. CTAB probably formed a bilayer, and it stabilized the metallic Cu nanoparticles colloidally and chemically.