Hydrothermal synthesis and electrochemical properties of ZnCo2O4 microspheres

Zinc cobalt oxide (ZnCo2O4) microspheres are prepared at three different hydrothermal process temperatures (100 °C, 130 °C, and 160 °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 nearband edge emission peak observed at 392 nm 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 °C) exhibit the superior specific capacitance of 500 F/g at 0.75 A/g current density and retain their specific capacitance of 80% at current density 2 A/g. ZnCo2O4 microspheres (SH3–160 °C) may be considered as a good candidate as electrode in supercapacitor applications.This work was supported by UGC Start-Up Research Grant No. F.30-326/2016 (BSR)