Ultrasonic-assisted synthesis of amorphous Fe3O4 with a high specific surface area and improved capacitance for supercapacitor

Fe3O4 nanoparticles with a high specific surface area (270.94 m2 g −1) exhibit high specific capacitance (335.5 F g −1 at 0.4 A g −1), good rate capability (54.7 F g −1 at 10 A g −1), and excellent cycling stability as applied in supercapacitors.