Intercalating graphene with clusters of Fe₃O₄ nanocrystals for electrochemical supercapacitors

A hierarchical nanostructure consisting of graphene sheets intercalated by clusters of Fe 3 O 4 nanocystals is developed for high-performance supercapacitor electrode. Here we show that the negatively charged graphene oxide (GO) and positively charged Fe 3 O 4 clusters enable a strong electrostatic interaction, generating a hierarchical 3D nanostructure, which gives rise to the intercalated composites through a rational hydrothermal process. The electrocapacitive behavior of the resultant composites is systematically investigated by cyclic voltammeter and galvanostatic charge-discharge techniques, where a positive synergistic effect between graphene and Fe 3 O 4 clusters is identified. A maximum specific capacitance of 169 F g −1 is achieved in the Fe 3 O 4 clusters decorated with effectively reduced graphene oxide (Fe 3 O 4 -rGO-12h), which is much higher than those of rGO (101 F g −1 ) and Fe 3 O 4 (68 F g −1 ) at the current density of 1 Ag −1 . Moreover, this intercalated hierarchical nanostructure demonstrates a good capacitance retention, retaining over 88% of the initial capacity after 1000 cycles.