Green Synthesized Carbon Quantum Dots from Polianthes tuberose L. Petals for Copper (II) and Iron (II) Detection

In this work carbon quantum dots (CQDs) are synthesized via a simple, low cost and as well as green way using tuberose (Polianthes tuberose L.) petals as the carbon source for the first time. We have not done any surface modification to the prepared CQDs although we directly employed this as fluorescent probe for the sensitive and selective detection of Fe2+ and Cu2+ ions. Both these ions drastically quench the emission intensity of the CQDs; in case of Cu2+ ions quenched CQDs EDTA results in regaining the fluorescence property but for Fe2+ ions quenched CQDs no such effect of EDTA is found. The limit of detection (LOD) is observed to be 200 nM in case of Cu2+ which is much lower than the safe limit provided by the WHO in drinking water. Hence the CQDs prepared in this simple and low cost method may find an important role in monitoring the water quality. The quantum yield of the CQDs prepared in our method is around 3%. Transmission electron microscope shows picture of nicely shaped CQDs with average size ~ 4 nm.