Co3O4/SiO2 nanocomposites for supercapacitor application

In this study, Co₃O₄/SiO₂ nanocomposites have been successfully synthesized by citrate–gel method by utilizing SiO₂ matrix for Co₃O₄ embedment. Spectroscopy analyses confirm the formation of high crystalline Co₃O₄ nanoparticles; meanwhile, microscopy findings reveal that the Co₃O₄ nanoparticles are embedded in SiO₂ matrix. Electrochemical properties of the Co₃O₄/SiO₂ nanocomposites were carried out using cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) in 5 M KOH electrolyte. The findings show that the charge storage of Co₃O₄/SiO₂ nanocomposites is mainly due to the reversible redox reaction (pseudocapacitance). The highest specific capacitance of 1,143 F g ^?1 could be achieved at a scan rate of 2.5 mV s^?1 in the potential region between 0 and 0.6 V. Furthermore, high-capacitance retention (>92 %) after 900 continuous charge–discharge tests reveals the excellent stability of the nanocomposites. It is worth noting from the EIS measurements that the nanocomposites have low ESR value of 0.33 Ω. The results manifest that Co₃O₄/SiO₂ nanocomposites are the promising electrode material for supercapacitor application.