Morphology‐controlled synthesis and structural features of ultrafine nanoparticles of Co 3 O 4 : An active electrode material for a supercapacitor

In this study, the authors present a morphology‐controlled synthesis strategy for the preparation of Co 3 O 4 nanoparticles. The importance of the fuel (ascorbic acid) to oxidiser (cobalt nitrate) ratio (F/O ratio) in obtaining evenly distributed nanoscale grain Co 3 O 4 with pure crystalline phases using the solution combustion method is proposed. The structural features of all the as‐formed cobalt oxide nanoparticles were studied using the powder X‐ray diffraction technique, a field emission scanning electron microscope and Raman spectroscopic techniques. The electrochemical characteristics of all the as‐formed cobalt oxide nanoparticle‐embedded electrodes were examined by cyclic voltammetry, galvanostatic charge–discharge studies and electrochemical impedance spectroscopy in a 2 M KOH solution. The electrochemical data demonstrated that the Co 3 O 4 nanoparticles showed good capacitive behaviour. The morphological changes in the Co 3 O 4 nanoparticles affect the charge storage mechanism, and Co 3 O 4 nanoparticles with an F/O ratio equal to 1 (COO2) showed the highest electrochemical property, with a specific capacitance of 166 F g −1 at a current density 0.5 A g −1 . The COO2 electrode material showed capacitance retention of 90% after 5000 cycles.