The Influence of Bath Concentration on Particle Size of Cobalt Nanoparticles

Cobalt nanoparticles have been widely used in magnetic storage media application. This study reports the characteristic and properties of Cobalt (Co) nanoparticles due to the effect of different bath concentrations. The Co nanoparticles were coated on the stainless steel substrate using different molar concentrations (M) of 0.05 M, 0.075 M and 0.1 M, respectively. The coating was done using electrodeposition method. Interestingly, the sphere particles surrounded by flakes were only found in the Co nanoparticles prepared in 0.075 M. This structure exhibited the smallest particles size, which is 83 nm. Besides, the nanoparticles also had the highest microhardness if compared to the Co nanoparticles prepared in 0.05 M and 0.1 M. The Co nanoparticles prepared in other concentrations were irregular structure without flakes. The polarization curves for all the nanoparticles showed the active behaviour without any distinctive to passivation. However, the corrosion rate of the sample prepared in 0.075 M was the lowest; 42.51 mpy compared to the other samples prepared in 0.05 M and 0.1 M, which were 176 mpy and 223.3 mpy, respectively. Hence, it was found that the bath concentrations affect the particle size of as-synthesized Co nanoparticles and finally changed the properties of final product.