The Effect of Liquid Environment on Composition, Colloidal Stability and Optical Properties of Nickel Nanoparticles Synthesized by Arc Discharge in Liquid

In this research, nickel nanoparticles were synthesized by arc discharge in different liquid media including deionized water, acetone, ethanol and methanol. Arc discharge is created with applying constant current 40 A between two nickel electrodes. Scanning electron microscopy (SEM), UV-visible spectroscopy and X-ray diffraction (XRD) were used for samples characterization. According to UV-visible spectra, nanoparticles synthesized in deionized water demonstrate metal oxide nanoparticles characteristic, but in organic media metallic nanoparticles were obtained. According to SEM images, the particle size of synthesized nanoparticles in deionized water, ethanol, methanol, and acetone are 25, 31, 38, and 45 nm respectively. Also SEM images revealed spherical nanoparticles with broad size distributions in all media, but the narrowest size distribution was observed in deionized water. Furthermore, synthesized nanoparticles in deionized water sedimented after a week. On the other hand, synthesized nanoparticles in organic media were stabled for long periods of time without sedimentation. It is noticeable that the most stable nanoparticles were observed in acetone. Oxidation of nanoparticles in water and perfect colloidal stability in acetone could be explained via reaction of dissolved oxygen in water with nickel nanoparticles and dipole-dipole interaction of acetone molecules with nanoparticles respectively.