Construction Of Iron Organic Framework Nanozymes And Their Catalytic Application

In recent years,various nanomaterials with enzyme-like catalytic activity(such as nano precious metals,metal oxides,carbon nanomaterials)have been widely used as nanozymes.Among them,metal-organic frameworks(MOFs),a unique porous material,were favored by researchers on account of abundant active sites,diverse types,functionability,and easy preparation.Although promising,they often suffer from shortcomings such as poor aqueous stability and low catalytic activity.In the present work,the efficient peroxidase-like nanozyme of iron based metalorganic frameworks were prepared via using Q-graphene(QG)and Cu-MOFs nonosheets(CuBDC)as scaffolds or templates.A high-performance colorimetric techniques based on nanozyme catalysis were developed to achieve sensitive and specific analysis of methidathion and pyrophosphate.The main contents include:(1)QG-MIL-101 nanocomposite with peroxidase-like catalysis activities have been successfully prepared via the one-pot hydrothermal route,which was used to establish a colorimetric analysis technology for the efficient methidathion detection(Chapter 2).It was discovered that the composite QG-MIL-101 presented dramatically improved peroxidase-like performance which can reach up to approximately triple the catalytic activity of pristine Fe metal organic framework(MIL-101).The introduction of Q-graphene(QG)can not only improve the aqueous stability of MIL-101,but also greatly promote its electron transfer speed towards increased catalytic activity.In addition,the peroxidase-like activity of QG-MIL-101 was greatly suppressed after adding methidathion.Therefore,a colorimetric method for the determination of methidathion based on the catalysis of QG-MIL-101 was established.The detection linear range was 0.50-60.0 μM,and the detection limit(LOD)was 0.018 μM.Importantly,the practical application of colorimetric method was further verified by the successful detection of pesticides in actual samples,which is a positive contribution to the detection of organophosphorus pesticides in food security and environmental protection.(2)Although iron-based metal-organic frameworks(Fe-MOFs)are promising nanozyme due to their iron active center and uniform pore structure,it is difficult to prepare two-dimensional Fe-MOFs nanomaterials due to the easy coordination of iron.In this work,a kind of Fe-BDC nanosheet was successfully prepared by using mesoporous copper based nanosheet(Cu-BDC)as template and cationic substitution strategy.It was found that the two-dimensional Fe-BDC showed excellent peroxide-like catalytic performance highly exposed catalytic active centers and enhanced electron transfer ability.A colorimetric analysis method based on Fe-BDC nanozyme was developed for the detection of pyrophosphate with a linear range of 1.0-40.0 μM and a detection limit of 0.37 μM.Furthermore,the feasibility of practical applications for the colorimetric methods based on Fe-BDC nanozyme has been demonstrated for pyrophosphate in tap water sample with the satisfying detection recoveries.