Urea-assisted liquid-phase exfoliation of natural graphite into few-layer graphene

Highlights: • A facile method to exfoliate natural graphite into graphene by assisting of urea was demonstrated. • The obtained graphene is non-oxidized with negligible defects. • The urea acts as "molecular wedge" which facilitates the exfoliation of graphite into graphene. The mass production of graphene with high quality is desirable for its wide applications. Here, we demonstrated a facile method to exfoliate natural graphite into graphene in organic solvent by assisting of urea. The exfoliation of graphite may originate from the "molecular wedge" effect of urea, which can intercalate into the edge of natural graphite, thus facilitating the production of graphene dispersion with a high concentration up to 1.2 mg/mL. The obtained graphene is non-oxidized with negligible defects. Therefore, this approach has great promise in bulk production of graphene with superior quality for a variety of applications.