Fluorine-rich graphene quantum dots by selective oxidative cutting of hydroxy fluorographene and their application for sensing of Fe (III) ions

Nucleophilic substitutions of fluorine moieties on fluorographite by hydroxyl groups are carried out by a strategy in which the parallel reductive defluorinations are minimised. Mild sonochemical exfoliation of the resulting product in water provides an aqueous dispersion of hydroxylated fluorographene (HFG) in which C-F bonds are largely semi-ionic in character. Upon subsequent hydrothermal treatment with hydrogen peroxide, additional fluorinations may take place because of adsorbed fluoride ions. Further, oxidative etching results in the formation of blue fluorescent fluorine-rich small sized (1-2.5 nm) graphene quantum dots (FGQDs) with excellent solubility and high stability. The prepared FGQDs is shown to be a good sensing platform for the detection of Fe3+ions in aqueous solution. A good linear response is obtained for Fe3+ concentrations over a range of 0-90 mu M with a limit of detection of 1.93 mu M.