Highly Selective and Sensitive Sensing of Toxic Mercury Ions Utilizing Carbon Quantum Dot-Modified Glassy Carbon Electrode

In this paper, a novel synthesis of 1 nm sized metal-free carbon quantum dots (CQDs) and their electrochemical application vis-a-vis mercury (Hg) sensing have been demonstrated. The characterization of synthesized CQDs was done by FT-IR, HR-TEM, XRD and UV-Vis analysis. Furthermore, the CQD-modified electrode shows an excellent sensing ability toward deleterious Hg ion even when 600-fold of excess of interfering ions such as Cu2+, Pb2+, Cd2+, Na+, K+, Mg2+, Ba2+, Bi2+, Fe2+, Zn2+ and Hg2+ are present. A wide linearity range (0.5-300 nM) and the lowest limit of detection (2.5 nM) are exhibited by the proposed sensor with potential scanning from - 0.7 to + 0.7 V vs Ag/AgCl at a scan rate of 20 mV. In addition, the CQD-modified electrode displays an outstanding recovery results toward Hg in various real water samples. This study promotes new possibilities of designing various electrochemical sensors based on CQD nanocomposite.