One-step synthesis of graphitic carbon nitride nanosheets with the help of melamine and its application for fluorescence detection of mercuric ions.

A facile, simple, and relatively environment-friendly hydrothermal approach was developed for one-step synthesis of graphitic carbon nitride nanosheets (GCNNs) using melamine and sodium citrate as the precursors. The prepared GCNNs emit strong fluorescence with a high quantum yield of 48.3%. The GCNNs were then characterized by various techniques including transmission electron microscopy, atomic force microscopy, X–ray diffraction, Fourier transform infrared spectroscopy, and UV–Vis absorption spectroscopy. In addition, the fluorescence quenching behavior of the GCNNS by mercuric ions (Hg 2+ ) was exploited to fabricate a label-free fluorescence quenching sensor for sensitive and selective detection of Hg 2+ . The results showed that there existed a linear relationship between the fluorescence intensity and the concentration of Hg 2+ from 0.001 to 1.0 μM with a detection limit of 0.3 nM. Finally, the sensor was successfully used to detection of Hg 2+ in water and milk samples. [ABSTRACT FROM AUTHOR]