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.