Copper hydroxide (oxide) / multiwalled carbon nanotubes nanocomposite-modified glassy carbon electrode (Cuhydroxide/oxide/MWCNTs/GCE) was successfully prepared by a novel film plating / cyclic voltammetry (CV) method, which exhibited marked synergistic catalytic effects on the electro-oxidation of NO2–. The preparation process, impedance behavior, and surface morphology of Cuhydroxide/oxide/MWCNTs/GCE were investigated by CV, electrochemical impedance spectroscopy, and scanning electron microscopy (SEM), respectively. The optimum preparation and test conditions for the electrode to have high catalytic activity were acquired. The linear range between the anodic current (Δia, µA) and NO2– concentration (c, mmol L−1) was 1.0 × 10−4 to 14.0 mmol L−1, and the corresponding calibration curve was Δia = −0.1504 + 57.954c (R = 0.9990, n = 32) with a detection limit of 0.03 µmol L−1 (S/N = 3). The Cuhydroxide/oxide/MWCNTs/GCE prepared in the optimal conditions showed good stability, high selectivity, low detection limit, and quick response (<0.2 s) to NO2– in phosphate buffer (pH 5.29) at 0.78 V, which has been successfully applied to the determination of NO2– in pickled vegetables with satisfactory results.
First Electrochemical Sensor (Screen-Printed Carbon Electrode Modified with Carboxyl Functionalized Multiwalled Carbon Nanotubes) for Ultratrace Determination of Diclofenac
