Hydroxylated graphene quantum dots as fluorescent probes for sensitive detection of metal ions

Highly sensitive methods are important for monitoring the concentration of metal ions in industrial wastewater. Here, we developed a new probe for the determination of metal ions by fluorescence quenching. The probe consists of hydroxylated graphene quantum dots (H-GQDs), prepared from GQDs by electrochemical method followed by surface hydroxylation. It is a non-reactive indicator with high sensitivity and detection limits of 0.01 μM for Cu²⁺, 0.005 μM for Al³⁺, 0.04 μM for Fe³⁺, and 0.02 μM for Cr³⁺. In addition, the low biotoxicity and excellent solubility of H-GQDs make them promising for application in wastewater metal ion detection.