Silver nanoparticles loaded on a hybrid of graphitic carbon nitride and reduced graphene oxide as a modifier for carbon paste electrode in determination of isoniazid

Silver nanoparticles were loaded on a covalently coupled hybrid of graphitic carbon nitride (gC₃N₄) and reduced graphene oxide (rGO) to modify a carbon paste electrode (CPE). The morphological and structural properties of this modifier (Ag–gC₃N₄–rGO) were well characterized by transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectrometry, and electrochemical impedance analysis. The performance of this constructed electrochemical sensor (Ag–gC₃N₄–rGO/CPE) was investigated by cyclic voltammetry and square wave voltammetry. The ternary Ag–gC₃N₄–rGO nanocomposite exhibited electrocatalytic properties toward isoniazid electrooxidation and effectively improved the electrochemical performance of CPE. Under optimized experimental conditions the Ag–gC₃N₄–rGO/CPE exhibited a linear dynamic range from 0.8 to 70 μM with a detection limit of 0.2 μM. The sensor was very effective for the detection of isoniazid in the presence of other reducible biological compounds and showed excellent repeatability and stability. Graphic abstract: