Urea-assisted aqueous exfoliation of graphite for obtaining high-quality graphene

Urea-assisted aqueous exfoliation of graphite was found to be more efficient than exfoliation in N,N-dimethylformamide (DMF), and high-quality graphene was obtained with a yield up to 2.4%. The mechanism in which a primary amine facilitates aqueous exfoliation was proposed and experimentally validated, which may inspire new strategies for efficient liquid exfoliation.