Hydrothermal synthesis and electrochemical properties of ZnCo2O4 microspheres

Zinc cobalt oxide (ZnCo2O4) microspheres are prepared at three different hydrothermal process temperatures (100 degrees C, 130 degrees C, and 160 degrees C) assisted with urea. XRD studies reveal the spinel face-centered cubic (Fd3m) structure of ZnCo2O4 microspheres. The optical and vibrational properties of the product are characterized by photoluminescence and FTIR studies. The strong near-band edge emission peak observed at 392nm corresponds to the direct recombination of the exciton-exciton collision process for all three synthesized products; SEM analysis reveals the complete growth stage of spherical ZnCo2O4 microspheres at three different temperatures. The electrochemical properties of synthesized ZnCo2O4 microspheres are analyzed by cyclic voltammetry, electroimpedance spectroscopy, and galvanostatic charging and discharging studies. ZnCo2O4 microspheres (SH3-160 degrees C) exhibit the superior specific capacitance of 500F/g at 0.75A/g current density and retain their specific capacitance of 80% at current density 2A/g. ZnCo2O4 microspheres (SH3-160 degrees C) may be considered as a good candidate as electrode in supercapacitor applications.