Novel Electrochemical Sensor for 3-Nitroaniline Based on Cd@CuO Modified Glassy Carbon Electrode

A cadmium-doped copper oxide nanocomposite (Cd@CuO) was successfully synthesized via a co-precipitation method and employed as an electrocatalytic modifier for a glassy carbon electrode (GCE) for the detection of 3-nitroaniline (3-NA). Structural and compositional analyses confirmed the successful incorporation of Cd into the CuO lattice. Electrochemical characterization using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed significantly enhanced electron-transfer kinetics and a marked reduction in charge-transfer resistance at the modified electrode compared to the bare GCE. Differential pulse voltammetry (DPV) showed a well-defined reduction peak for 3-NA at approximately −0.45 V in phosphate buffer solution (pH 3). The sensor exhibited a linear response over the concentration range of 0.099–0.99 μM, with a low detection limit of 8.0 × 10⁻⁸ M. Furthermore, the developed sensor demonstrated good selectivity in the presence of common aromatic interferents, satisfactory repeatability, and reliable performance in real water samples. These findings highlight the strong potential of Cd@CuO nanocomposites as effective electrode modifiers for the sensitive electrochemical detection of nitroaromatic pollutants.