Magnetite Nanoparticles In-Situ Grown and Clustered on Reduced Graphene Oxide for Supercapacitor Electrodes.

FeO nanoparticles with average sizes of 3-8 nm were in-situ grown and self-assembled as homogeneous clusters on reduced graphene oxide (RGO) via coprecipitation with some additives, where RGO sheets were expanded from restacking and an increased surface area was obtained. The crystallization, purity and growth evolution of as-prepared FeO/RGO nanocomposites were examined and discussed. Supercapacitor performance was investigated in a series of electrochemical tests and compared with pure FeO. In 1 M KOH electrolyte, a high specific capacitance of 317.4 F g at current density of 0.5 A g was achieved, with the cycling stability remaining at 86.9% after 5500 cycles. The improved electrochemical properties of FeO/RGO nanocomposites can be attributed to high electron transport, increased interfaces and positive synergistic effects between FeO and RGO.