Novel nitrogen-doped carbon dots prepared under microwave-irradiation for highly sensitive detection of mercury ions

In this paper, new nitrogen doped carbon dots with a high quantum yield and novel optical properties were synthesized by a simple and fast one step microwave-assisted synthesis. Citric acid monohydrate was used as a carbon source and 2,2-dimethyl-1,3-propanediamine as nitrogen source. The prepared N-CDs were characterized by Fourier transform infrared, Raman, UV-visible and photoluminescence spectroscopies. Transmission electron microscope (TEM) images revealed that the N-CDs have distinctive flake-shape morphology. The N-CDs exhibit bright blue luminescence and quenching response towards Hg²⁺ ions. The quenching sensitivity was investigated. The results indicate a limit of detection as low as 7.63 nM and a linear relationship over the range 0-4.2 μM. In addition, the prepared N-CDs were tested as sensor for pH in the range from 1 to 7.