Synthesis and Characterization of Ternary α-Fe 2 O 3 /NiO/rGO Composite for High-Performance Supercapacitors.

Herein, pure α-Fe 2 O 3 , binary α-Fe 2 O 3 /NiO, and ternary α-Fe 2 O 3 /NiO/rGO composites were prepared by a hydrothermal method. The properties of the prepared materials were studied by powder X-ray diffraction, scanning electron microscopy, TEM, XPS, and Brunauer-Emmett-Teller techniques. The clusters of smaller α-Fe 2 O 3 nanoparticles (∼30 nm) along with conducting NiO was freely covered by the rGO layer sheet, which offer a higher electrode-electrolyte interface for improved electrochemical performance. The ternary composite has shown a higher specific capacitance of 747 F g -1 @ a current density of 1 A g -1 in a 6 M KOH solution, when compared with that of α-Fe 2 O 3 /rGO (610 F g -1 @1 A g -1 ) and α-Fe 2 O 3 (440 F g -1 @1 A g -1 ) and the nanocomposite. Moreover, the ternary α-Fe 2 O 3 /NiO/rGO composite exhibited a 98% rate capability @ 10 A g -1 . The exceptional electrochemical performance of ternary composites has been recognized as a result of their well-designed unique architecture, which provides a large surface area and synergistic effects among all three constituents. The asymmetric supercapacitor (ASC) device was assembled using the ternary α-Fe 2 O 3 /NiO/rGO composite as the anode electrode (positive) material and activated carbon as the cathode (negative) material. The ASC device has an energy density of 35.38 W h kg -1 at a power density of 558.6 W kg -1 and retains a 94.52% capacitance after 5000 cycles at a 1 A g -1 current density.