Graphene quantum dots via ion modification for improving photoluminescence stability in aqueous solution with heavy metal ions

Graphene quantum dots (GQDs) have shown growing potential in the applications of ion detection, anti-counterfeiting ink and light-emitting devices. However, the photoluminescence (PL) properties of GQDs will be lost when they interact with some heavy metal ions. Effective strategies to improve PL stability are still limited. In this work, we prepared a new kind of GQDs modified by scandium ions (Sc 3+ ) to improve the PL of GQDs in aqueous solution containing heavy metal ions. The Sc 3+ modified GQDs (Sc@GQDs) show a slight fluorescence enhancement compared with pristine GQDs. In addition, the PL of pristine GQDs could be quenched by Fe 3+ /Cu 2+ /Cr 3+ , while the PL of Sc@GQDs was kept stable with these heavy metal ions. Meanwhile, GQDs modified by Al 3+ and Ga 3+ exhibit similar results, which further verifies the universality of this method that GQDs modified by specific metal ions to maintain the PL of GQDs with heavy metal ions. As applications, Sc@GQDs may have great potential in the fields of fluorescent flexible device and fluorescent ink.