NiFe2O4 Nanoparticles Anchored on Porous Graphene Sheets Offered Robust Electrochemical Performance for Supercapacitor Applications

Abstract

A Facile solvothermal method is used for the synthesis of porous graphene − NiFe2O4 (PGNF) nanocomposite. Thorough elemental, diffraction, microscopic and spectroscopic studies confirmed the formation of PGNF composite in which, the NiFe2O4 nanoparticles are covered over the porous graphene (PG) surface strongly depicting the formation of composite structure. Among the obtained composites, the 10 PGNF composite showed a high surface area of 107 m2 g-1, with large pore volume which will be favorable for the charge storage property. Utilizing the material as an electrode for supercapacitors in a 2 M KOH aqueous electrolyte, the electrode displayed a high capacity value of 1465.0 F g-1 at a scan rate of 5 mV s-1, and 1320.0 F g-1 (594 C g-1) at a current density of 1 A g-1, along with high capacitance retention rate of 94 % after 10000 discharge cycles. The fabricated symmetrical supercapacitor device by using the best performed electrode (10 PGNF), displayed a high capacitance value of 303 F g-1 at a scan rate of 5 mV s-1, with 96 % initial capacitance retention value after a long 10000 discharge cycles along with a good energy density of 5.5 Wh kg-1 while maintaining a high power density of 1008.0 W kg-1 at a current density of 4 A g-1, and still produces an energy density of 4.0 Wh kg-1 at a high power density of 3600.0 W kg-1 at the applied current density of 14 A g-1. The superior results showed by the material is mainly due to the inclusion of PG having high surface area and pore volume, in addition to that NiFe2O4 nanoparticles presence also increased the electronic conductivity by acting as spacer to keep the neighboring sheets apart along with it has maintained the mechanical strength during continuous electrochemical redox process. Thus, we believe that the increased electrochemical performance is mainly due to the synergetic effect of the materials which not only provided enough electroactive channels for the smooth passage of electrolyte ions but also maintained the hybrid structure intact in the ongoing electrochemical process. The obtained result supports the promising utility of this material for future electrochemical energy storage devices.Keywords: Porous graphene, NiFe2O4 nanoparticles, composite, specific capacitance, cyclic stability.