A New Nanocomposite Electrode of Carbon Quantum Dots Doped Functionalized Multi-walled Carbon Nanotubes for Lethal Mercury Sensing

In this work, a new nanocomposite, carbon quantum dots (CQD) functionalized multi-walled carbon nano tubes (f-MWCNTs), was prepared by facile sonochemical treatment of CQD and f-MWCNTs. The synthesized CQD@f-MWCNTs was then used as a novel electrode material to construct a non-enzymatic electrochemical sensor for selective and sensitive detection of toxic mercury (Hg2+) ions. Due to the high catalytic activity of carbon based CQD and the excellent charge transfer property between acid groups of the ligands in f-MWCNTs, the obtained sensor exhibited high sensitivity for Hg2+ detection under optimum experimental conditions. A linear relationship between the current and toxic Hg2+ concentration was shown in the range of 1.0 nM to 12.0 nM with the corresponding sensitivity of 59.16 μAmM−1. In addition, the limit of detection was calculated to be 0.5 nM (S/N = 3). Furthermore, with the advantages of good repeatability, stability and selectivity, the fabricated sensor could be applied to detect Hg2+ successfully in real samples such as river, industrial and tap waters. The results obtained from this study will certainly accelerate the applications of CQD@f-MWCNTs in the electrochemical field and provide insights into design of multifunctional non-enzymatic sensing materials for various applications in bio-catalysis, bio-analysis and water testing.