Abstract
Designing sustainable efficient peroxidase nanozymes and elucidating its peroxidase-like mechanism are very important for constructing colorimetric sensing platforms. Herein, a sustainable peroxidase nanozyme, porphyrin functionalized montmorillonite (PorMMT) loaded Cu2O-Fe3O4 nanocomposites, is prepared by the two-step hydrothermal method and can be recycled conveniently by virtue of magnetism of Fe3O4 from the composite (Cu2O-Fe3O4/PorMMT). Cu2O-Fe3O4/PorMMT peroxidase nanozyme can quickly catalyze the oxidation of the colourless substrate 3,3',5,5'-tetramethylbiphenylamine (TMB) by H2O2 into a blue product (oxTMB) only in 3 min. Compared with pure MMT, Cu2O and Fe3O4 individual, Cu2O-Fe3O4/PorMMT exhibits the higher peroxidase-like activity. The catalytic activity of Cu2O-Fe3O4/PorMMT is reached the maximum at pH = 4 and T = 50 degrees C. The catalytic behaviors of Cu2O-Fe3O4/PorMMT follow the Michaelis-Menten kinetic equation. The catalytic mechanism of Cu2O-Fe3O4/PorMMT is from the produced active species including superoxide free radicals (center dot O-2(-)) and holes (h(+)). Based on the peroxidase-like activity of Cu2O-Fe3O4/PorMMT, a fast convenient colorimetric sensing platform has been designed to detect H2O2 and hydroquinone (HQ), respectively. H2O2 detection can be realized in the linear range of 5-10 mM with the limit of detection (LOD) of 2.68 mM, as well as hydroquinone (HQ) in the linear range of 5-50 mu M with a much lower LOD of 4.37 mu M. The convenient visual sensing platform has a potential application in monitoring HQ remains in lakes and rivers near dressing plants.