Nitrogen doped graphene quantum dots as a fluorescent probe for mercury(II) ions

A highly selective fluorescent probe for Hg2+ is reported. It consists ofnitrogen doped graphene quantum dots (NGQDs) that are nearly sphericalin shape, have an average diameter of 2.7nm and excitation-independent emission. The bluefluorescence of the NGQDs (with maximum excitation/emission at 378/447nm) is quenched by Hg2+ due to both dynamic and static quenching. The probe has a wide detection range (2.5M - 800M) and a limit of detection of 2.5M. The dynamic andstaticquenching constants are 417M(-1) and 63500M(-1), respectively. The probe was used to quantfy Hg2+ in spiked real water samples with satisfactory results.