Construction and Performance Characterization of α‑Fe₂O₃/rGO Composite for Long-Cycling-Life Supercapacitor Anode

Thumb-ring-like α-Fe₂O₃ and reduced graphene oxide (rGO) composites, α-Fe₂O₃/rGO, have been synthesized via a simple hydrothermal method accompanied by surface potential tuning. The obtained samples exhibit good electrochemical performance with a wide negative potential window of −1–0.2 V vs Ag/AgCl when serving as supercapacitor electrodes. There is only about 10% decay after 11 000 cycles of galvanostatic charge–discharge (GCD) test. After a few tens of cycles of cycling activity, the capacitance achieved a stable value of 255 F g^–1 at 0.5 A g^–1 and 174 F g^–1 at 5 mV s^–1; 75% of the capacitance was retained when the scan rate increased to 200 mV s^–1, indicating satisfactory power density. Most attractively, along with cycling, the α-Fe₂O₃ particles begin to be well-wrapped by rGO gradually from prior stacked structure, which is supposed to be the key factor for the exceptional high cycling stability.