Nitrogen-Doped Graphene Quantum Dots Synthesized By C-60/Nitrogen Plasma With Excitation-Independent Blue Photoluminescence Emission For Sensing Of Ferric Ions

Graphene quantum dots (GQDs) exhibit unique luminescent properties because of quantum confinement and edge effects. However, low quantum yields and tedious multistep processes have limited universal application of GQDs. In this article, we report a novel simple and green method to prepare nitrogen-doped GQDs (N-GQDs) that exhibit excellent photophysical properties. The N-GQDs were synthesized in a one-step process by means of transforming C-60 molecules in a microwave-activated nitrogen plasma process. The as-synthesized N-GQDs were dispersed into graphene sheets, forming composite nanodots with a uniform size distribution. The resulting N-GQDs showed bright blue photoluminescence emission with an excitation-independent behavior. The physical mechanisms responsible for the unique photophysical properties of the N-GQDs were elucidated in the study. The N-GQDs exhibited high sensitivity and selectivity to ferric ion sensing with a limit of detection of 4 x 10(-7) M, which demonstrates the potential to be an excellent nanosensor for ion sensing.