A colorimetric sensor of H2O2 based on Co3O4-montmorillonite nanocomposites with peroxidase activity

Herein, Co3O4 nanoparticles deposited on montmorillonite (Co3O4-MMT NPs) were synthesized via a facile method and characterized by energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). Significantly, the as-prepared Co3O4 MMT NPs were demonstrated to possess an intrinsic peroxidase-like activity, which could rapidly catalytically oxidize the peroxidase substrate 3,30,5,50-tetramethylbenzidine (TMB.2HCl) by H2O2, accompanied by a visible color change (colorless to blue); these NPs were then used to develop a sensitive colorimetric sensor for the detection of H2O2. The catalytic reaction of Co3O4-MMT NPs followed the Michaelis-Menten kinetics equation, and the composites showed good affinity towards TMB. Via the proposed method, H2O2 can be detected in the range of 10-100 mM with a low detection limit (DL) of 8.7 mM. Fluorescence data reveal that electron transfer among the catalyst, TMB, and H2O2 may contribute to the peroxidase-like activity of the Co3O4-MMT NPs. Finally, a colorimetric method was proposed for the detection of H2O2, and the robustness of the Co3O4-MMT NPs was quite good. The sensor of H2O2 based on Co3O4-MMT NPs can exhibit great potential applications in the medical, food, and environmental fields.