Electrochemical monitoring of PFOA in water using a Cu@rGO/Nb2O5 Nanohybrid sensor platform

Per - and polyfluoroalkyl substances (PFAS), particularly perfluorooctanoic acid (PFOA), are persistent environmental contaminants that pose significant risks to ecosystems and human health due to their widespread occurrence, chemical stability, and bioaccumulative nature. Conventional analytical methods for PFOA determination are often expensive, labor-intensive, and unsuitable for rapid on-site monitoring. In this study, a novel Cu@rGO/Nb 2 O 5 nanohybrid-based electrochemical sensor was developed for the sensitive and selective detection of PFOA in environmental water samples. The nanohybrid was synthesized through a controlled multistep chemical approach and comprehensively characterized using UV–Visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical performance was evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and electrochemically active surface area (ECSA) measurements. The Cu@rGO/Nb 2 O 5 -modified electrode exhibited enhanced electrocatalytic activity, reduced charge-transfer resistance, and accelerated electron-transfer kinetics compared with the bare glassy carbon electrode. The sensing mechanism is primarily attributed to the synergistic effects of Cu nanoparticles, reduced graphene oxide, and Nb 2 O 5 , which facilitate PFOA adsorption through π-π interactions and promote efficient charge transfer. Under optimized conditions (pH 7.2, 0.1 M PBS), the sensor demonstrated a linear detection range of 10–50 μM, an LOD of 131 nM, and a sensitivity of 1.377 × 10 −5 mA/(nM·mm 2 ), with excellent reproducibility (RSD ≤ 1.67%, n = 5) and outstanding selectivity in the presence of common interfering species. Furthermore, successful application in river water, tap, ground, lake and wastewater samples yielded satisfactory recovery values, confirming its practical applicability in complex environmental matrices. These findings highlight the potential of the Cu@rGO/Nb 2 O 5 nanohybrid as a promising platform for rapid, cost-effective, and reliable electrochemical monitoring of PFOA contamination in aquatic environments.