Electrochemical Determination of Nitrite in Environmental Water Using Ultrathin g‐C 3 N 4 Nanosheets

Herein, we report an ultrathin graphitic carbon nitrite nanosheet (GCN NS)‐based electrochemical sensor platform for the sensitive detection of nitrite (NO 2 − ), a hazardous environmental pollutant. Ultrathin GCN NSs were synthesized via a facile single‐step thermal polymerization strategy, enabling reduced layer thickness and enhanced electrochemical activity. The formation and structural features of ultrathin GCN NS are being confirmed using comprehensive physicochemical characterization techniques, including X‐ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), Raman spectroscopy, and field emission scanning electron microscopy (FESEM) analysis. The electrochemical oxidation of NO 2 − at GCN NS‐modified glassy carbon electrode (GCN NS/GCE) was investigated using cyclic voltammetry and amperometric techniques. The amperometric results show a wide linear range from 0.1 to 12 μM with an LOD of 0.051 μM. This high sensitivity is likely due to the reduced layer thickness of GCN NS, which enhances electron transport, decreases charge carrier recombination, and increases edge sites and structural defects within the two‐dimensional framework. Notably, the GCN NS/GCE demonstrated excellent selectivity toward NO 2 − even in the presence of common interfering metal ions at concentrations 10 times higher than NO 2 − . Furthermore, the sensor reliably detected NO 2 − in real wastewater and borewell water samples with good recovery rates, highlighting its strong potential for practical environmental monitoring applications.