Study On The Preparation And Catalysis Property Of Fe-N-C Material As Oxidase-like Nanozymes

Nanoenzymes possess many advantages over natural enzymes,which has attracted broad attention of research and application in the field of catalysis in recent years.Oxidases-like nanozymes are one of the very important category of nanozymes.However,only noble metal such as Pt-based materials and some certain kind of materials are currently used for the synthesis of oxidases-like nanozymes,which limits the development of nanomimetic oxidases.Therefore,the research of non-Pt materials for the synthesis of oxidase-like nanozyme is a hotspot and a difficult topic at present.On the other hand,Fe-N-C materials had been discovered in recent years as a class of Pt alternative materials with excellent catalytic oxygen reduction(ORR)properties.In this work,we have extensively explored the research achievement and cutting-edge of development of nanozymes,deeply considered the key scientific issues of oxidase-like nanozyme,and realized the possible internal relations between the oxidase-like nanozymes and ORR catalysts.For the reasons above,the enzyme mimic properties and applications of the Fe-N-C nanomaterials were studied,and a general strategy for the research and development of non-Pt oxidase-like nanozymes materials was proposed.Specific content as follows:(1)Oxidase-like activity of the Fe-N-C nanoparticle cluster.We obtained a porous Fe-N-C nanoparticle cluster by heating the Prussian blueprecursor without oxygen at 600℃.The testing results showed that the Fe-N-C nanoparticle cluster had an excellent oxidase-like and peroxidase-like catalytic performance of catalyzing oxidization of the 3,3’,5,5’-tetramethylbenzidine(TMB)in acidic solution.Further,we used the Fe-N-C oxidase-like nanozyme to prepare a membrane enzyme reactor,and tested its catalytic performance.A good potential for application of the reactor has been found.(2)A dual-cell device designed as an oxidase mimic and its use for the study ofoxidase-like nanozymes.In this chapter,we designed and used a dual-cell device with salt bridge basedon the analysis of the catalytic mechanism of natural oxidase.The substrate oxidation sites and the ORR sites was successfully separated,which suggested that a new device was developed to study the catalytic properties of oxidase-like nanozymes.It was found that TMB oxidation is insensitive to surface sites of the catalytic materials,which indicated that the nanomaterials of oxidase-like nanozymes using TMB as substrates requires only oxygen reduction reaction sites on the surface to achieve the performance of the oxidase-like enzymes.It also means that the ORR catalyst material can be combined with any conductive material to prepare oxidase-like nanozymes.These results provide a theoretical guidance for the design,preparation,and screening of nano-mimetic oxidase materials.(3)Preparation and application of Fe-N-C@SiO2 oxidase-like nanozyme.The surface of mesoporous SiO2 nanospheres was coated with zeolitic Fe-N-C materials to prepare a Fe-N-C@SiO2 nanostructure,and the thickness of the layer is about 10 nm.The test results show that the nanoenzymes have excellent oxidase-like properties in both acidic and alkaline environments,and the synthesis of oxidase-like materials on common carriers is complished.(4)Application of Fe-N-C nanozyme of dopamine electrochemical analysis.Dopamine(DA)is an important neurotransmitter of the human nervous system.and a key marker of neural disease in the clinical diagnosis.In this study,the oxidase-like nanozyme which obtained from chapter(1)was used to modify a glassy carbon electrode(GCE).The treatment temperature was adjusted to 550 ℃,and morc Fe-N-C sites were found in the nanozyme.The modified electrode was used to selectively detect DA in a phosphate buffer containing 100 μM UA and 100μM AA with linear sweep voltammetry(LSV)and differential pulse voltammetry(DPV).The results showed that the modified electrode can eliminate interference of AA and reduce the signal of UA.The liner range exhibits two segment.i.e.,5 to 100 μM and 100 to 700 μM.respectively.The sensitivity is 8.32×10-2 A·M-1 and 3.44×10-2 A·M-1,respectively.And the limit of detection(LOD)is 5 μM with the LSV method.These results indicate that the Fe-N-C nanozyme is outstanding for selectively electrochemical detection of DA.