Effect of Hetero‐Atom Doping on the Structure and Optical Properties of Carbon Quantum Dots for the Sensitive Detection of Heavy Metal Ions

Metal pollution in water sources due to modernization is a human health and environmental problem. Therefore, the highly fluorescent boron‐ and nitrogen‐doped and nitrogen‐doped carbon quantum dots (B,N‐CQDs and N‐CQDs, respectively) were synthesized and investigated to be used as a fluorescence sensor for metal ion detection. In this study, the synthesized B,N‐CQDs and N‐CQDs had an average size of 4–6 nm and 3–4 nm, respectively. The B,N‐CQDs presented high sensitivity as 0.0090, 0.0086 and 0.0091 units per micromolar for Cr 3+ , Cu 2+ and Fe 2+ , respectively, whereas the N‐CQDs showed sensitivity as 0.0047, 0.0102, 0.0095 and 0.0121 units per micromolar for Cr 3+ , Cu 2+ , Fe 2+ and Ni 2+ , respectively. In the concentration range of 10–80 μM, the detection limits of B,N‐CQDs and N‐CQDs were found to be in the range of 13.9–65.5 μg/L and 14.9–38.3 μg/L, respectively. The result of the study clearly indicates that B,N‐CQDs and N‐CQDs can be seen as metal ion sensing devices with high sensitivity and low cost.