Size controlled reverse micelle synthesis of metallic cobalt nanoparticles

Scope and method of study. This study examined the effects of process variables on the particle size distribution of metallic cobalt nanoparticles synthesized by a reverse micelle process. The factors examined were metal salt concentration, reducing agent to metal ion ratio, and water content. The range of interest for the cobalt particle diameter was 1--5 nm. Characterization methods used to determine the particle diameter included dynamic light scattering (DLS) and tapping mode-atomic force microscopy (TM-AFM).; Findings and conclusions. The following effects were determined for the experimental system: (1) Average particle diameter increases with increasing metal salt concentration. (2) Average particle diameter decreases as the reducing agent to metal salt ratio increases. (3) Average particle diameter increases with increasing water content. (4) One two-way interaction exists between the reducing agent ratio and the water content. The effects for the polydispersity of the particles, embodied in the peak width of the distribution, were similarly determined as follows: (1) Average peak width increases with increasing metal salt concentration. (2) Average peak width decreases as the reducing agent to metal salt ratio increases. (3) Average peak width decreases with increasing water content. (4) Three two-way interactions for all three factors.