Electrocatalytical Nitrite Oxidation via Manganese and Copper Oxides on Carbon Screen-Printed Electrode

Nitrite (NO2−) has long been recognized as a contaminant of concern due to its detrimental effects on both human health and the environment. As a result, there is a continuing need to develop sensitive, real-time, low-cost, and portable systems for the accurate detection of trace levels of NO2− in drinking water. We present a novel, low-cost, and easy-to-fabricate amperometric sensor designed for detecting low concentrations of NO2− in drinking water. The fabrication technique involves the electrodeposition of manganese and copper oxides onto a carbon working electrode. CuO and MnO2 act synergistically as efficient catalysts for the electrooxidation of nitrite to nitrate (NO3−) thanks to their complementary redox properties. The resulting sensor exhibits high catalytic activity toward the electrooxidation of NO2−, with a sensitivity of 10.83 μA/µM, a limit of detection (LOD) of 0.071 µM, and a good linear dynamic concentration range (0.2–60 µM). The sensor’s performance was evaluated against potential interfering analytes (NO3−, Cl−, NH4+, and NH2Cl), all of which showed negligible interference. Reproducibility (maximum standard deviation 2.91%) and repeatability (usable up to three times) were also evaluated.