ZnFe2O4 nanorods on reduced graphene oxide as advanced supercapacitor electrodes

Binary transition metal oxides (BTMOs) are active materials, which have the potential for supercapacitor materials due to their high theoretical capacity. Herein, a BTMO based on zinc and iron was experimentally investigated in both the bare and hybrid forms, i.e. as ZnFe2O4 nanorods and ZnFe2O4 nanorods on reduced graphene oxide (rGO). After the synthesis, the products were investigated by different analytical techniques. The performance of the nano-engineered products as supercapacitor electrode materials were probed by electrochemical analysis. The electrochemical results obtained from the cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy showed the huge potential of the prepared electrodes for supercapacitor applications. The specific capacitance of ZnFe2O4-rGO was estimated as 1419 F/g with cyclic stability of 93% after 5000 successive voltammetry cycles at the scan rate of 10 mV/s. The electrochemical tests confirmed that the addition of rGO, owing to its large surface area and high electrical conductivity, improved the discharge time and cyclic stability besides increasing the specific conductance of the electrodes. The enhanced capacitance of the ZnFe2O4-rGO electrode recommends that the ion diffusion rate and the active redox site have been increased for capacitive behavior. Therefore, this composite can be a good candidate for energy storage.