Sequential electrochemical fabrication of an overoxidized polythiophene/graphene/Ag nanocomposite-modified pencil graphite electrode for highly sensitive electrochemical determination of bisphenol A

In this study, a sensitive and reliable electrochemical sensor for the determination of bisphenol A (BPA) was developed based on a silver nanoparticle–polythiophene–graphene composite modified pencil graphite electrode (GR/PTh/AgNP/PGE). The sensing interface was fabricated through electropolymerization of thiophene in the presence of graphene, followed by controlled chronoamperometric deposition of Ag nanoparticles and a subsequent overoxidation step to enhance surface functionality. Under optimized conditions, the sensor displayed a wide linear dynamic range from 0.25 to 1000 µM, with a limit of detection (LOD) of 110.99 nM and a limit of quantification (LOQ) of 369.98 nM. The proposed sensor demonstrated good repeatability (RSD = 4.85%), excellent reproducibility, and satisfactory operational stability. The practical applicability of the sensor was successfully validated through real sample analysis in tap water, yielding recovery values between 100.26% and 104.77% with low relative standard deviations, indicating high accuracy and minimal matrix effects. In addition, the structural and morphological properties of the modified electrodes were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX).