A glycine-functionalized graphene quantum dots synthesized by a facile post-modi fi cation strategy for a sensitive and selective fl uorescence sensor of mercury ions

In this work, we have developed a facile method for the synthesis of glycine-functionalized graphene quantum dots (Gly-GQDs) through post-modification of graphene quantum dots with Gly under alkaline conditions. The as-synthesized Gly-GQDs exhibit an excellent blue emission at 444 nm, independent of excitation, as well as a high quantum yield (QY) of 35.7%. The Gly-GQDs have a narrow size distribution with an average size of 5.9 nm. Moreover, the as-prepared Gly-GQDs showed a better selective and sensitive recognition capability towards mercury ion (Hg2+) in aqueous solutions with a low detection limit of 8.3 nM, compared with GQDs and other nitrogen-doped GQDs synthesized through the one-step solvent thermal method. Gly-GQDs are successfully applied for the determination of Hg2+ in real water samples. This work shows a new promising approach for the design and synthesis of desirable GQDs with a given function. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

In this study, Gly-GQDs were synthesized through post-modification of graphene quantum dots with glycine under alkaline conditions, showing excellent blue emission, high quantum yield, and enhanced selective and sensitive recognition capability towards mercury ion in aqueous solutions. The work demonstrates a promising approach for designing and synthesizing desired GQDs with specific functions.