Facile synthesis of hexagonal ZnO nanoplate-MnO2 nanocomposites for supercapacitor electrode material

A binary zinc oxide/manganese oxide (ZnO/MnO 2 ) nanocomposite was synthesized through a co-precipitation method. The phase structure and internal morphology of ZnO, MnO 2 , and ZnO/MnO 2 were investigated using XRD and FESEM analyses. The surface elemental composition and valence states of the elements present in the ZnO/MnO 2 nanocomposite were examined using XPS. All the physicochemical characterization techniques confirmed the successful formation of the synthesized nanomaterials. Furthermore, electrochemical measurements were performed for all the prepared electrode materials using a three-electrode system with 1 M Na 2 SO 4 as the electrolyte. Cyclic voltammetry analysis revealed a maximum specific capacitance (573 (F/g)) for the binary ZnO/MnO 2 electrode, compared to ZnO (268 F/g) and MnO 2 (490 F/g) at a scan rate of 5 mV/s. Electrochemical stability analysis indicated a high capacitance retention of 87% for the ZnO/MnO 2 electrode after 5000 charge-discharge cycles. From the EIS analysis, ZnO/MnO 2 exhibited a lower ESR value (3.35 Ω) than the other two electrodes, with a slight increase observed after cycling. These results indicate that the electrochemical characteristics of zinc oxide are significantly enhanced by the incorporation of manganese oxide nanostructure, demonstrating that the ZnO/MnO 2 nanocomposite is a promising electrode material for supercapacitor applications.