N-Doped Carbon Dots Derived from Melamine and Triethanolamine for Selective Sensing of Fe3+ Ions

Abstract

This work reports nitrogen-doped carbon dots (NCDs) as a selective sensing probe to detect Fe³⁺ in water samples. NCD probes were synthesized via solvothermal method using nitrogen-rich melamine and triethanolamine as precursors. Properties of the resulting NCDs were studied using different characterization techniques, through which N-doping was confirmed. The quantum yield of obtained NCDs was measured to be 21. When excited at 370nm, the excellent blue emission property makes this probe adoptable for selectively sensing Fe³⁺ in practical water samples. The limit of detection (LOD) was identified as 216nM with a good linear range between the concentrations of 0.2-2μM. The obtained LOD is far less than the World Health Organization (WHO) permissible limits of Fe³⁺ in water. Interference studies reveal that the presence of other competing ions did not alter the sensing of Fe³⁺, even at the presence of 10 equivalents which indicates the high selectivity of NCDs towards Fe³⁺. The reversibility studies showed that adding a cheap and readily available EDTA ligand to the NCD results in fluorescence regeneration, leading to exceptional reusability for the detection of Fe³⁺. So, the synthesized NCDs can be used as a suitable probe for the selective determination of Fe³⁺ in real water samples.