Synthesis of hexagonal-symmetry alpha-iron oxyhydroxide crystals using reduced graphene oxide as a surfactant and their Li storage properties

Microcrystalline alpha-iron oxyhydroxide/reduced graphene oxide (alpha-FeOOH/rGO) samples have been successfully synthesized by a facile hydrothermal process. The alpha-FeOOH/rGO samples are either hexagonal disks with a diameter of similar to 1 mu m and a thickness of 300 nm or hexapods with a diameter of similar to 2 mmand a thickness of 700 nm, while only bulk and aggregated FeOOH is observed without the addition of graphene oxide sheets. The size and shape of the alpha-FeOOH depend on the reaction time, concentration of Fe3+, and the addition of graphene oxide. The growth of the hexagonal disks and hexapods is mainly due to a series of phase and structural transformations. The alpha-FeOOH/rGO displays superior anode performance with a high reversible specific capacity of 569 mA h g(-1) at the 50(th) cycle.