and its critical micelle concentration (CMC) is 0.9–1.0 mmol/L [51].It was reported that the transition from spherical micelles torod-like micelles takes place at concentrations higher than theCMC value of CTAB, whereas, the size of its micelles increaseswith its concentration increase [30]. During our preparation ofcobalt oxalate we have utilized a CTAB concentration of around62.5 mmol/L. This indicates that CTAB can easily form rod-likemicelles comprising the Co2+ions. When H2C2O4aqueous solu-tion is added the C2O42−ions penetrate throughout these micellesinteracting with Co2+ions yielding CoC2O4·2H2O. Utilizing higherMWPs (700 W) during the CoC2O4·2H2O preparation would leadto a higher evaporation rate of water. In other words, the higherMWP will decrease the H2O/CTAB ratio, which would lead to largerCoC2O4·2H2O particles. During the subsequent calcination process,the CoC2O4·2H2O precursor decomposes giving Co3O4nanoparti-cles that approximately maintain the morphology of the rod-likeprecursor.