MOFs-derived Fe-N-C nanozyme for colorimetric detection of hdroquinone
Objective Hydroquinone is a phenolic compound widely used in industry.It is difficult to degrade in the aquatic ecological envi-ronment and is harmful to human health.Therefore,constructing a simple and sensitive method for the detection of hydroqui-none is of great significant.Methods In this study,an MOFs-derived Fe-N-C catalyst was synthesized through a simple chemical doping method and high-temperature pyrolysis,using an Fe-ZIF-8 precursor.The physicochemical properties of Fe-N-C were characterized in detail through SEM,TEM,XRD,FTIR,and XPS.The effect of the introducing Fe3+on the enzyme activity of the catalyst was stud-ied.The enzyme-like activity,catalytic mechanism,and kinetic parameters of Fe-N-C were systematically investigated.Based on the enzyme-like activity of Fe-N-C,a colorimetric sensor for the detection of hydroquinone was developed.Results and Discussion Based on the aforementioned characterization and experimental findings,Fe-N-C exhibited excellent peroxidase-like activity and weak oxidase-like activity.In addition,in the presence of hydrogen peroxide,OPD and ABTS as substrates were also oxidized to yellow and blue products by Fe-N-C,with characteristic absorption peaks at 448 nm and 416 nm,respectively.Additionally,the poisoning experiment with KSCN showed that Fe-Nx was the main active site in Fe-N-C catalyst.The study of the catalytic mechanism confirmed that·OH,O2·-and 1O2 were active oxygen radicals playing a major role in the catalytic oxidation of TMB.The catalytic activity of Fe-N-C nanozymes was further studied through steady-state kinetic analysis.The Km and Vmax of Fe-N-C for TMB were 0.134 mmol/L and 0.754 × 10-7 M·s-1,respectively,while those for H2O2 were 16.535 mmol/L and 2.533 × 10-7 M·s-1,respectively.Finally,the colorimetric sensor detected HQ in a linear range of 0～33 μmol/L with a detection limit of 0.356 μmol/L.Through anti-interference experiments,the established colorimet-ric sensing platform showed robust anti-interference ability and selectivity in detecting hydroquinone.Conclusion The introduction of Fe3+significantly improves the enzyme-like activity of N-C nanomaterials.Fe-N-C exhibits excellent peroxidase-like activity,which can rapidly oxidize the chromogenic substrate 3,3',5,5'-tetramethylbenzidine(TMB)to blue.Fe-Nx is the main active site of Fe-N-C nanozymes,and hydroxyl radical(·OH),superoxide radicals(O2·-)and singlet oxygen(1O2)are the main reactive oxygen species(ROS).Hydroquinone is a strong reducing organic pollutant that can reduce blue oxTMB to a colorless state.Based on this,a sensing platform for colorimetric detection of HQ was constructed.This method has good sensitivity and selectivity for hydroquinone,which expands the application of MOFs-based nanozymes in the field of environmental pollutant detection.
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