Mg-ZnO/CNT Nanocomposite as Electrode Materials with Enhanced Electrochemical Performance for Supercapacitor Applications

The present research work reported the study of nanocomposites of undoped and Mg-doped ZnO with CNT as electrode materials for supercapacitor application. The undoped ZnO/CNT and Mg-doped ZnO/CNT nanocomposites (i.e., 10 % Mg-doped and 20 % Mg-doped) were synthesized using a cost-effective blending-assisted hydrothermal method. The morphological (FESEM & TEM) studies revealed that the diameter of CNT was similar to 7 nm and the ZnO nanoparticles were spherical in shape with an average particle size of similar to 5 nm. In addition, it was also found that 10 % Mg-ZnO and 20 % Mg-ZnO had a sheet-like structure. XRD and FTIR studies further confirmed the successful doping of Mg in ZnO and CNT nanocomposites. BET analysis showed that the value of specific capacitance increased with the increase in surface area. Further, the electrochemical performance of these nanocomposites revealed that the higher doping percentage, 20 % Mg-ZnO/CNT nanocomposite achieved the highest specific capacitance value i.e., 458.5 F/g at 0.1 A/g current density in 3M H2SO4 electrolytic solution, having a retention of 99.8 % after 12,00 long cycles. In addition, the charge storage mechanism revealed that the as-synthesized nanocomposites showed both the diffusion-controlled and capacitive-controlled behaviors. Thus, a higher value of specific capacitance with excellent cyclic stability indicated the higher efficiency of Mg-doped ZnO/CNT nanocomposite for future supercapacitor applications.