Improving safety and efficiency in graphene oxide production technology

Abstract

Chemical conversion of natural graphite into graphene based nanomaterials is achievable and scalable by designed Hummers’ method. Conventionally, high amount of manganyl compound (Mn2O7 or MnO3+) and explosive risk of thermal runaway in the reaction are still the key concerns of efficiency and safety in the production technology. In this manuscript, reaction mechanism and innovative strategy are applied in the cascade design of graphite oxide synthesis. By optimizing the amounts of reactive chemicals (KMnO4, H2SO4 and water), utilizing exothermic energy (for self-heating reaction and exfoliation) and combining reaction divisions (for control of thermal runaway), the principal issues of safety and efficiency are improved for simple and practical preparation of graphene oxide nanomaterials. The cascade synthesis occurs in just 8 h without external supply of thermal energy, producing solid yield of more than 130%wt. Obtained graphene oxide nanosheets have good colloidal property, uniform decoration of functional groups, appropriate C/O atomic ratio of 1.62 and optoelectronic band gap energy of 3.33 eV. Characterization of graphene oxide membranes showed elemental oxygen mapping, C/O atomic ratio of 2.12, ultimate tensile strength of 59.17 MPa and strong elastic modulus of 10.123 GPa. Hydrogel of partially reduced graphene oxide was prepared and analyzed, revealing the C/O atomic ratio of 2.63 and band gap energy of 2.88 eV. The technological improvements open a safe and efficient route of graphene oxide production for scientific and industrial purposes.