Design and Synthesis of Multilevel Structured Co₃O₄ Double-shell Dodecahedron as Non-enzymatic Electrochemical Sensor for H₂O₂ Detection (Supporting Information)

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.