Design and Synthesis of Multilevel Structured Co<sub>3</sub>O<sub>4</sub> Double-shell Dodecahedron as Non-enzymatic Electrochemical Sensor for H<sub>2</sub>O<sub>2</sub> Detection

In this work, we use ZIF-67 as a template to prepare multilevel structured Co3O4 with a high surface area. The synthesized materials are characterized by SEM, TEM, XRD, and N2 physisorption. The double-shell dodecahedron multilevel structure of Co3O4 (DS Co3O4) has the most favorable morphology and largest specific surface area, and is demonstrated to be an effective electrochemical non-enzymatic H2O2 sensor. The efficiency arises from the unique multilevel structure of DS Co3O4, providing abundant active sites for H2O2 oxidation. The sensor demonstrates a rapid response time of 5 seconds, high sensitivity of 1168.9 µA mM−1 cm−2 (µA (mmol L−1)−1 cm−2), and a limit of detection of 0.048 µM (µmol L−1, S/N = 3) within a linear range of 0.0005 to 10 mM. These values are significantly superior to those of other high performance Co3O4-based H2O2 sensors. The as-fabricated DS Co3O4 sensors exhibit excellent sensitivity, selectivity, and long-term stability, making them highly promising sensors materials for H2O2 detection.