A green method to synthesize AuNPs/mpg-C3N4 nanocomposites for constructing anti-interference electrochemical sensing interface toward methylmercury

Methylated mercury is a bio-magnifier that readily crosses the blood-brain barrier exerting neurotoxic effects. Therefore, the development of a rapid and in situ method of methylmercury (CH 3 Hg + ) detection is research priority. We report a sensitive electrochemical method for the detection of CH 3 Hg + using a modified glassy carbon electrode with Au nanoparticles-graphitic carbon nitride (AuNPs/mpg-C 3 N 4 ). The AuNPs/mpg-C 3 N 4 nanocomposites was synthesized by photochemical method and characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), X-ray photoelectron spectroscopic (XPS), Fourier transform infrared spectrometer (FTIR). The results showed that Au nanoparticles were successfully loaded on the surface of mpg-C 3 N 4 and dispersed uniformly. AuNPs/mpg-C 3 N 4 combined the excellent catalytic properties of AuNPs and unique structure of mpg-C 3 N 4 to improve the electrochemical sensing performance of CH 3 Hg + . The AuNPs/mpg-C 3 N 4 GCE show a high sensitivity for CH 3 Hg + determination using Differential pulse stripping voltammetry (DPSV). The CH 3 Hg + calibration curve is linear within 1 μg/L ∼25 μg/L. The sensitivity and detection limit of CH 3 Hg + is 0.285 μA/μg −1 L and 0.103 μg/L (S/N = 3), respectively. The Hg 2+ shows chemical interference in CH 3 Hg + detection, which is minimized by the addition of SnCl 2 or Diethylene triamine pentaacetic acid (DTPA). We also determined the CH 3 Hg + concentration of natural waters with a ±106% spike recovery. A newly developed AuNPs/mpg-C 3 N 4 modified GCE sensor provides a promising platform for CH 3 Hg + detection in natural water.