Investigations on supercapacitor performance of novel ZnO-CeO2-rGO nanohybrid prepared via hydrothermal method for energy storage applications and their charge storage mechanism

Abstract

Nanohybrids which can utilize the synergistic effect to enhance the electrochemical activity as an electrode material for supercapacitor has gained immense interest recently.Here,we report a ZnO-CeO2-rGO ternary nanohybrid synthesized via hydrothermal method which can combine the pesuedocapacitance nature of transition metal oxide and electric double layer behavior of reduced graphene oxide. The electrochemical activity was thoroughly investigated using cyclic voltammometry(CV) and galvanostatic charge discharge for the ternary using a two electrode set up with 2 M KOH as the electrolyte. Cyclic stability analysis was done and impedance analysis was carried out using electrochemical impedance spectroscopy. Among the samples the best electrochemical performance was observed for ZnO –CeO2-rGO (Ter-2) with weight ratio 85:10:5. Ter-2 exhibited specific capacitance of 26 F/g from CV in the 2-electrode setup and a capacity retention as high as 93 % even after 5000 cycles of charge-discharge. It was observed that the addition of rGO improved the cyclic stablity as well as specific capacitance. Systematic analysis of charge storage mechanism was done using Dunn's and Trasatti's method. The results substantiate that Ter-2 is a potential supercapacitor electrode material with excellent electrochemical activity.