Graphene oxide microspheres prepared by a simple, one-step ultrasonication method

We demonstrate herein a simple, one-step method for preparing stabilized microspheres of graphene oxide (GO), by applying ultra-sonic power to a biphasic system. The microsphere's size was affected by the pH of the aqueous solution, ranging from a few mm to μm. Further characterization indicated that the microsphere's inner content is composed mainly of organic solvents, though water and GO molecules may be also present at the microsphere's core. The microspheres were stable for several months without a significant conformation change. We predict that the stability arises from hydrophobic and hydrophilic interactions between the GO sheets and the solvents. Changing the organic solvent resulted in changes in the microsphere's morphology.