Metal–organic framework templated synthesis of Co3O4 nanoparticles for direct glucose and H2O2 detection

Abstract

Co₃O₄ nanoparticles (NPs) with an average diameter of about 20 nm were synthesized by using MOFs as a template. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the as-prepared Co₃O₄ NPs. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to confirm the structure of the Co₃O₄ NPs. Then the Co₃O₄ NPs were modified on a glassy carbon electrode (GCE) to obtain a non-enzymatic glucose and H₂O₂ sensor. The NPs show electrocatalytic activity toward oxidation of glucose and H₂O₂ in alkaline medium. For glucose detection, the developed sensor shows a short response time (less than 6 s), a high sensitivity of 520.7 μA mM⁻¹ cm⁻², a detection limit of 0.13 μM (S/N = 3), and good selectivity. The high concentration of NaCl does not poison the electrode. Its application for the detection of glucose in a human blood serum sample shows good agreement with the results obtained from the hospital. Furthermore, the proposed sensor was used for the detection of H₂O₂. The results indicate that the detection limit and sensitivity for H₂O₂ are 0.81 μM and 107.4 μA mM⁻¹ cm⁻², respectively. Determination of H₂O₂ concentration in a disinfectant sample by the proposed biosensor also showed satisfactory result. The high sensitivity and low detection limit can be attributed to the excellent electrocatalytic performance of the as-prepared Co₃O₄ NPs. These results demonstrate that the as-prepared Co₃O₄ NPs have great potential applications in the development of sensors for enzyme-free detection of glucose and H₂O₂.