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

Hollow-sphere Co3O4 nanoparticles were successfully synthesized by direct pyrolysis of cobalt-containing zeolitic imidazolate frameworks (ZIF-67) precursor. The transformation process from ZIF-67 to Co3O4 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 Co3O4 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 Co3O4 hollow sphere was exploited as an electrocatalyst for sensitive H2O2 detection in an alkaline medium. The Co3O4 hollow sphere modified glassy carbon electrode exhibited a fast response time (within 3s), a high sensitivity of 120.55 mu A/mM (959.79 mu A.mM(-1).cm(-1)), a broad linear range from 0.4 mu M to 2.2 mu M, a detection limit of 0.105 mu M (S/N= 3), and good stability and selectivity, suggesting its excellent performance towards H2O2 detection. (C) 2015 Elsevier Ltd. All rights reserved.