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

Abstract

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 3,3′,5,5′-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 μM with a low detection limit (DL) of 8.7 μM. 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.