Rational Design of High-Performance Electrodes Based on Ferric Oxide Nanosheets Deposited on Reduced Graphene Oxide for Advanced Hybrid Supercapacitors

Abstract

The core strategy for constructing ultra-high-performance hybrid supercapacitors is the design of reasonable and effective electrode materials. Herein, a facile solvothermal-calcination strategy is developed to deposit the phosphate-functionalized Fe₂O₃ (P-Fe₂O₃) nanosheets on the reduced graphene oxide (rGO) framework. Benefiting from the superior conductivity of rGO and the high conductivity and fast charge storage dynamics of phosphate ions, the synthesized P-Fe₂O₃/rGO anode exhibits remarkable electrochemical performance with a high capacitance of 586.6 F g^-1 at 1 A g^-1 and only 4.0% capacitance loss within 10 000 cycles. In addition, the FeMoO₄/Fe₂O₃/rGO nanosheets are fabricated by utilizing Fe₂O₃/rGO as the precursor. The introduction of molybdates successfully constructs open ion channels between rGO layers and provides abundant active sites, enabling the excellent electrochemical features of FeMoO₄/Fe₂O₃/rGO cathode with a splendid capacity of 475.4 C g^-1 at 1 A g^-1. By matching P-Fe₂O₃/rGO with FeMoO₄/Fe₂O₃/rGO, the constructed hybrid supercapacitor presents an admirable energy density of 82.0 Wh kg^-1 and an extremely long working life of 95.0% after 20 000 cycles. Furthermore, the continuous operation of the red light-emitting diode for up to 30 min demonstrates the excellent energy storage properties of FeMoO₄/Fe₂O₃/rGO//P-Fe₂O₃/rGO, which provides multiple possibilities for the follow-up energy storage applications of the iron-based composites.

Keywords: energy density; ferric oxide; ferrous molybdate; hybrid supercapacitors; reduced graphene oxide.