Electrolytic synthesis of metallic zinc nanoparticles

The present paper describes fabrication of metallic zinc (Zn) nanoparticles in aqueous solution. An aqueous colloidal solution containing metallic Zn nanoparticles was prepared by electrolysis of Zn salt aqueous solution using two metallic Zn plate electrodes. In methods A and B, sonication was performed after and during the electrolysis, respectively. As a result, method B was found to be suitable for synthesis of metallic Zn nanoparticles without producing large particles with sizes from a few micrometers to a few tens of micrometers. Investigation of the effect of electrolysis time revealed that the metallic Zn nanoparticles were produced in three steps: (1) the hexagonal plate-shaped particles were produced on the cathode, (2) the particles were peeled off the cathode and dispersed in the solution, and (3) the dispersed particles were broken apart in the solution phase by sonication to form smaller particles. Particle size decreased with decreasing ultrasonic wave frequency based on attenuation in medium and/or cavitation stability and decreasing current based on a decrease in reduction rate. As a result, metallic Zn nanoparticles as small as 19.1 ± 5.1 nm were fabricated in 1 h at 28 kHz and 0.03 A.