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

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 (FTIR) 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 mu A mM(-1) cm(-2), a detection limit of 0.13 mu M (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 mu M and 107.4 mu A 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.