Non-Enzymatic Co₃O₄ Nanostructure-Based Electrochemical Sensor for H₂O₂ Detection

This article describes the synthesis of nanostructured cobalt oxide on iron wires and its application for the detection of hydrogen peroxide as working electrode for non-enzymatic electrochemical sensor. Cobalt oxide was obtained by the hydrothermal synthesis method using chloride and acetate anions. The resulting nanostructured coating obtained from the chloride precursor is a uniform homogeneous porous network of long nanofibers assembled into regular honeyсomb-like formations. In the case of an acetate precursor, instead of nanofibers, petal-like nanostructures assembled into honeycomb agglomerates are observed. The structure, surface, and composition of the obtained samples were studied using field-emission scanning electron microscopy along with energy-dispersive spectroscopy and X-ray diffractometry.

The resultant nanostructured specimens were utilized to detect H₂O₂ electrochemically through cyclic voltammetry, differential pulse voltammetry, and i-t measurements. A comparative research has demonstrated that the nanostructures produced from the chloride precursor exhibit greater sensitivity to H₂O₂ and have a more appropriate morphology for designing a nanostructured sensor. A substantial linear correlation between the peak current and H₂O₂ concentration within the 20 to 1300 μM range was established. The Co₃O₄ electrode obtained exhibits a sensitivity of 505.11 μA·mM⁻¹, and the electroactive surface area is calculated to be 4.684 cm². Assuming a signal-to-noise ratio of 3, the calculated limit of detection is 1.05 μM. According to the interference study, the prevalent interfering agents, such as ascorbic acid, uric acid, NaCl, and glucose, do not influence the electrochemical reaction. The obtained results confirm that this sensor is suitable for working with complex analytes.The actual sample assessment demonstrated a recovery rate exceeding 95 %.