Highly sensitive and selective detection of Cd2+ and Pb2+ in aqueous system using miniaturized Bi2O3/plastic chip electrode based electrochemical sensor

A facile and miniaturized Bi₂O₃/plastic chip electrode (PCE) was designed for concurrent electrochemical identification of Cd²⁺ and Pb²⁺. The identification was carried out through the potentiostatic electrodeposition of bismuth onto a PCE. The synthesized Bi₂O₃/PCE was analyzed employing scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to assess their morphology, crystal structure, and elemental composition, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to explore electrochemical characteristics of synthesized electrodes. Under optimal experimental conditions, Bi₂O₃/PCE demonstrated significant electro-catalytic performance for Cd²⁺ and Pb²⁺ at lower pH, with augmented square wave-anodic stripping peak currents compared to unmodified PCE. Bi₂O₃/PCE exhibits an exceptionally high sensitivity of 12 μA L cm⁻² μg⁻¹ for Cd²⁺ and 20 μA L cm⁻² μg⁻¹ for Pb²⁺ with low detection limit of 0.09 μg L⁻¹ for Cd²⁺ and 0.07 μg L⁻¹ for Pb²⁺. The developed sensor shows highly reproducible and repeatable performance with an extensive linear range 0.2–––300 μg L⁻¹ for Cd²⁺ and 0.1–––250 μg L⁻¹ for Pb²⁺ and also exhibits good selectivity, even when accompanied by common interfering ions.