NiFe2O4/G-C3N4 modified pencil graphite electrode for mercury (II) detection

The design and development of composite electrodes towards the trace-level detection of Hg(II) ions has triggered paramount importance in the area of electrochemistry. In this context, pencil graphite electrode was modified with NiFe2O4/G-C3N4, wherein bimetallic oxides were heterogeneously grown over the g-C3N4 sheets through a wet chemical approach. The results derived from transmission electron microscopy and X-ray diffraction analysis indeed reflected that NiFe2O4 were uniformly distributed over the sheet surface and complemented with effective interactions between them. The composites were coated over a pencil graphite electrode (PGE) and were used for the electrochemical detection of Hg(II) ions under various conditions. The cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DPASV) reveal better electrochemical performance of modified electrodes compared to bare PGE, G-C3N4/PGE, and NiFe2O4/PGE. The improved charge transfer kinetics at the electrode-electrolyte interface were the dominant factor to exhibit higher performance. The proposed sensor showed acceptable reproducibility and stability under the optimal reaction conditions. Additionally, the sensor showed a broad linear range from 10 to 800 nM with a limit of detection (LOD) of 2.49 nM. Further, the fabricated sensor has been successfully employed to determine Hg(II) contents in real water sample matrices.