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

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 FeO (P-FeO) 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-FeO/rGO anode exhibits remarkable electrochemical performance with a high capacitance of 586.6 F g at 1 A g and only 4.0% capacitance loss within 10 000 cycles. In addition, the FeMoO/FeO/rGO nanosheets are fabricated by utilizing FeO/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 FeMoO/FeO/rGO cathode with a splendid capacity of 475.4 C g at 1 A g. By matching P-FeO/rGO with FeMoO/FeO/rGO, the constructed hybrid supercapacitor presents an admirable energy density of 82.0 Wh kg 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 FeMoO/FeO/rGO//P-FeO/rGO, which provides multiple possibilities for the follow-up energy storage applications of the iron-based composites.