Synergistic amalgamation of ZIF-8 into ZIF-67 framework for enhanced supercapacitor application

Abstract

This study employed a direct combination method to synthesize ZIF-8, ZIF-67, and a ZIF-8/ZIF-67 composite. Using electrochemical impedance spectroscopy (EIS), galvanostatic charge-discharge (GCD), and cyclic voltammetry (CV), the charge storage behavior of the prepared electrode was investigated through electrochemical analysis. ZIF-8, ZIF-67, and ZIF-8/ZIF-67 have specific capacitances of 223, 255, and 609 F/g, respectively. The ZIF-8, ZIF-67, and ZIF-8/ZIF-67 electrodes had energy densities of 15.8, 38.8, and 69 Wh/kg, respectively. The power density of ZIF-8, ZIF-67, and ZIF-8/ZIF-67 electrodes was determined to be (469.41, 745.64, and 779) W/kg at a current density of 1 A/g. The retention plot of ZIF-8, ZIF-67, ZIF-8/ZIF-67 electrode shows efficiency of 65%, 92% and 63%, respectively, indicating their suitability for supercapacitor applications. The bandgap energies of ZIF-8 (2.50 eV) and ZIF-67 (2.77 eV) indicate their potential as semiconductors in electronic applications, with ZIF-67 having a higher energy and thus greater electronic characteristics. The composite ZIF-8/ZIF-67 has a reduced bandgap (2.35 eV), indicating increased charge carrier mobility due to the mixing of frameworks. The XRD diffraction peaks at 22.09° (110), 26.62° (200), 38.49° (211), and 47.27° (220) correspond to unique crystallographic planes for ZIF-8 and ZIF-67, indicating their intact structure and phase composition. The XRD investigation shows that the ZIF-8/ZIF-67 composite maintains its crystallinity despite modifications, as evidenced by its comparable peak characteristics.