Fe2Mo3O8/exfoliated graphene oxide: solid-state synthesis, characterization and anodic application in Li-ion batteries

Abstract

An Fe₂Mo₃O₈/exfoliated graphene oxide (EG) composite with unique morphology is synthesized by a novel solid-state reduction method. Graphene oxide (GO), FeC₂O₄·2H₂O and MoO₃ are heated together at 750 °C for 8 h under an Ar atmosphere to obtain Fe₂Mo₃O₈/EG as the resultant material. The morphology of the as-synthesized Fe₂Mo₃O₈/EG powder as observed in electron micrographs confirmed the presence of layer-like EG and densely populated Fe₂Mo₃O₈ hexagonal platelets. Thermogravimetric analysis showed that Fe₂Mo₃O₈ and EG are in the composite at 98 and 2 wt%, respectively. The structural analysis of the as-synthesized Fe₂Mo₃O₈/EG confirmed that Fe₂Mo₃O₈ platelets are crystallized in the hcp crystal system. Raman scattering analysis further confirmed the presence of Fe₂Mo₃O₈ and EG in the as-synthesized Fe₂Mo₃O₈/EG composite. X-ray photoelectron spectroscopy confirmed that Fe and Mo elements are in the II and IV oxidation states in the as-synthesized Fe₂Mo₃O₈/EG composite, which when tested as an anode material of a half-cell Li-ion battery, exhibited a high reversible capacity of 945 mA h g⁻¹ at 50 mA g⁻¹ current rate. This work paves the way to synthesize other graphene–metal oxide composites (with unique metal oxide morphologies) for their use as anode materials in Li-ion batteries.