Photoluminescent carbon quantum dots synthesized from Plumeria leaves as metal ion sensor

The present work focuses on synthesis, characterization and applicability of green carbon quantum dots (CQDs) from leaves of Plumeria obtusa plant as a fluorescent metal ion sensor. These precursors undergo hydrothermal treatment, which produces fluorescent CQDs. The morphological and optical studies of synthesized CQDs have been studied by FESEM image analysis, XRD, UV–Vis absorption, photoluminescence and FTIR spectroscopy. The average size of prepared green CQDs estimated was ~ 4 nm, which matches with the result from FESEM image analysis. Based on absorption data, the direct band gap of 3.4 eV has been determined for the prepared CQDs. ‘Turn off’ fluorescence is observed in the presence of Fe³⁺ ions. High sensitivity and low detection limit of our synthesized CQDs for metal ions sensing have established their prominent candidature to be used as good efficient biocompatible fluorescent sensor.