Graphitic carbon quantum dots as a fluorescent sensing platform for highly efficient detection of Fe3+ ions

Abstract

Reported here is a green synthesis of graphitic carbon quantum dots (GCQDs) as a fluorescent sensing platform for the highly sensitive and selective detection of Fe³⁺ ions. Through the electrochemical ablation of graphite electrodes in ultrapure water, uniform GCQDs with graphitic crystallinity and oxygen containing groups on their surfaces have been successfully prepared. The absence of acid, alkali, salt and organic compounds in the starting materials effectively avoids complex purification procedures and environmental contamination, leading to a green and sustainable synthesis of GCQDs. The oxygen functional groups (e.g., hydroxyl, carboxyl) contribute to the water solubility and strong interaction with metal ions, which enable the GCQDs to serve as a fluorescent probe for the highly sensitive and selective detection of Fe³⁺ ions with a detection limit as low as 2 nM. The high sensitivity of our GCQDs could be attributed to the formation of complexes between Fe³⁺ ions and the phenolic hydroxyls of GCQDs. The fluorescence lifetime of GCQDs in the presence and absence of Fe³⁺ was tested by time-correlated single-photon counting (TCSPC), which confirmed a dynamic fluorescence quenching mechanism.