Metal-free poly(o-toluidine)/g-C3N4 nanocomposite for efficient electrochemical sensing of 4-nitrophenol

Developing highly sensitive electrodes remains a challenge for contemporary environmental monitoring systems. This study addresses this limitation by fabricating electrochemical sensors based on a novel conducting polymer nanocomposites. The poly(o-toluidine) (POT)/g-C₃N₄ nanocomposite was synthesized via in situ chemical oxidative polymerization using ammonium peroxydisulfate as the oxidant and camphor sulfonic acid (CSA) as the dopant. Comprehensive characterization, including FTIR, FESEM, and HRTEM analyses, confirmed the interaction between POT and g-C₃N₄ and revealed a ring-like morphology with a thin CSA-doped polymer layer. Differential pulse voltammetry (DPV) with a modified glassy carbon electrode modified by the CSA-doped POT/g-C₃N₄ nanocomposite was used to detect 4-nitrophenol. Under optimized conditions, the sensor exhibited a linear detection range of 0.0025–0.140 μM, a sensitivity of 15.32 μA μM⁻¹ cm⁻², And a detection limit (LOD) of 0.00769 μM or 7.69 nM. The modified electrode showed satisfactory recovery rates and robust stability in real sample analyses, demonstrating its potential for practical environmental pollutant detection.