Highly sensitive H2O2 sensor based on Co3O4 hollow sphere prepared via a template-free method

Abstract Hollow - sphere Co 3 O 4 nanoparticles were successfully synthesized by direct pyrolysis of cobalt-containing zeolitic imidazolate frameworks (ZIF-67) precursor. The transformation process from ZIF-67 to Co 3 O 4 hollow sphere was characterized by powder X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis. It is found that the as-prepared Co 3 O 4 nanoparticles possesses uniform hollow spherical structure with many voids on the surface. It's worth noting that the high density of metal sites, the ordered arrangement of Co, as well as the uniform crystal size and regular morphology was inherited from ZIF-67, resulting in an excellent accessibility of Co. The resulting Co 3 O 4 hollow sphere was exploited as an electrocatalyst for sensitive H 2 O 2 detection in an alkaline medium. The Co 3 O 4 hollow sphere modified glassy carbon electrode exhibited a fast response time (within 3s), a high sensitivity of 120.55 μA/mM (959.79 μA∙mM −1 ∙cm −1 ), a broad linear range from 0.4 μM to 2.2 mM, a detection limit of 0.105 μM (S/N=3), and good stability and selectivity, suggesting its excellent performance towards H 2 O 2 detection.