Design and construction of ZIF(8 and 67) supported Fe3O4 composite as advanced materials of high performance supercapacitor

Two hierarchical structures were designed using Fe3O4 as a core and ZIF-8 or ZIF-67 as a support. Fe3O4@ZIF-8 and Fe3O4@ZIF-67 were prepared through a facial one-step solvothermal method at room temperature. Results confirmed the microporous and mesoporous morphology of Fe3O4@ZIF-8 and Fe3O4@ZIF-67 nanoparticles. The porous structure of ZIF combined with Fe3O4 causes the composite electrode to have a short ion diffusion path, fast ion/electron transfer with maximized use of active material, resulting in high specific capacitance. Electrochemical efficiency of the sample was studied in 6 M KOH electrolyte using cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy techniques. Results implied that Fe3O4@ZIF-8 and Fe3O4@ZIF-67 demonstrate maximum specific capacitance of 870 and 1334 F/g, respectively, at 1 A/g. In addition, an asymmetric device was fabricated using Fe3O4@ZIF-67 as a promising electrode, and active carbon as negative electrode. Fe3O4@ZIF-67//AC delivered a high-energy density of 27.9 W h/kg and power density of 5488 W/kg, as well as good cyclability with 87% of initial capacitance retained after 3000 consecutive charge/ discharge rounds.

Automated summary

Hierarchical structures were designed using Fe3O4 as a core and ZIF-8 or ZIF-67 as a support, resulting in high specific capacitance composite electrodes. Fe3O4@ZIF-67 exhibited a higher specific capacitance compared to Fe3O4@ZIF-8 in 6 M KOH electrolyte. Both electrodes showed promising potential for use in asymmetric devices with good cyclability.