A simple method to prepare uniform Co nanoparticles

The authors report a simple method to fabricate cobalt nanoparticles with homogeneous spherical shape and narrow size distribution, which can be easily scaled up for large quantity production. The method is based on conventional chemical reduction method by using NaBH/sub 4/ as areducing reagent; however, the process is modified so that the particle nucleation and growth are controlled by immediately transferring the formed particles out of the reaction site. In addition, the chemical reaction is carried out in a nonaqueous solution to avoid possible formation of oxides as well as borides.