Sodium Fluoride-Assisted Hydrothermal Exfoliation of Graphite into Graphene as Filler of Epoxy Resin Coating To Protect Aluminum

The low yield of graphene in the sonication-assisted aqueous-phase exfoliation is one of the challenges to its large-scale production in industry. Here, we report that hydrothermal exfoliation of graphite into graphene in NaF and polyether F127 (F127) solution can achieve a high concentration (0.55 mg mL^–1) or yield (8.2%) of graphene in a low-cost, environmentally friendly manner. The defect of as-exfoliated graphene is comparable to that produced by the sonication-assisted exfoliation. In the exfoliation process, NaF and F127 are regarded as the intercalator and stabilizer. The thermal motion of H₂O and F^–/Na⁺ ion pairs, Brownian motion of graphite particles, and thermally agitation of graphite interlayers are the main driving force for exfoliating graphite. In addition, as filler of epoxy resin (EP), the graphene can enhance considerably the anticorrosion performance of EP coating. The hydrothermal exfoliation in NaF and F127 solution provides a new choice for the large-scale production of graphene.