Cobalt carbonate and cobalt oxide nanoparticles synthesis, characterization and supercapacitive evaluation

Taguchi robust design methodology was used to optimize direct precipitation reaction conditions for simple and fast synthesis of cobalt carbonate nanoparticles. The effects of several parameters that influence on particle size of prepared cobalt carbonate were investigated. The significance of these parameters on the size of cobalt carbonate particles were quantitatively evaluated by using of analysis of variance (ANOVA). The results showed that flow rate and the concentrations of cobalt and carbonate solutions have significant effect on the size of cobalt carbonate nanoparticles. Also, optimum conditions for synthesis of cobalt carbonate nanoparticles via precipitation reaction were achieved. The ANOVA demonstrated that under optimum condition, cobalt carbonate nanoparticles will have of 39.6 +/- 2.2 nm sizes. In addition, the solid state thermal decomposition reaction of precursor was used for preparation of Co3O4 nanoparticles. The results showed that the Co3O4 nanoparticles synthesized by thermal decomposition of cobalt carbonate nanoparticles have 53 nm sizes. Cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy were used to investigate the supercapacitive property of the Co3O4 electrode. The Co3O4 electrode shows high specific capacitance of 396 F g(-1) at scan rate of 2 mV s(-1) in 2.0 M H2SO4 electrolyte. Thus, the prepared electrode could be used for supercapacitor.