Hollow graphene oxide spheres self-assembled by W/O emulsion

Hollow graphene oxide spheres (HGOSs) were fabricated from graphene oxide nanosheets (GONs) utilizing a water-in-oil (W/O) emulsion technique without surfactant. Effects of oxidation treatment and water removal on the formation and morphology of HGOSs are investigated. The oxidation time for preparing GONs is a crucial factor for the formation and morphology of HGOSs. We found that with increasing oxidation time, the morphology and surface topography of HGOSs vary from irregular and rough to uniform and smooth shape with decreasing diameter. Moreover, the electrochemical performance of HGOSs as anode materials in lithium-ion batteries was evaluated. The heat-treated HGOSs exhibit a 485 mAh g−1 reversible capacity and high rate performance thanks to the hollow structure, thin and porous shells consisting of graphene.