Preparation Of Metal-Organic Frameworks/3D Carbon Composite And Application In Electrochemical Sensing

Metal-organic frameworks(MOFs)are a new type of porous material composed of metal ions or metal clusters and organic bridging ligands with self-assembled site bonds.They have unique physical and chemical properties.Compared with traditional porous materials,MOFs have many advantages such as high porosity,large specific surface area and diverse and flexible structures.Therefore,MOFs have been extensively studied in the field of new functional materials.However,the poor conductivity and electrochemical stability of MOFs hinder their application in the field of electrical analysis.Combining MOFs with other superior functional materials can not only make full use of their advantages,but also make up for their shortcomings,thereby further expanding the application of MOFs in the field of electrochemical sensing.In this paper,two metal-organic framework/3D carbon composites,Co-MOF-74@MC and MOF-818@RGO/MWCNTs,were synthesized by combining metal-organic framework with three-dimensional carbon nanomaterials.The morphology and composition of these two composites were characterized by various methods.Based on these two composites,fast and sensitive electrochemical sensors for detecting anti-tuberculosis drugs(isoniazid,pyrazinamide)and phenolic compounds(caffeic acid,chlorogenic acid,and gallic acid)were constructed.The specific work of the paper is as follows:1.Co-MOF-74@MC composites were obtained by embedding rod-shaped Co-MOF-74 crystals into mesoporous carbon(MC)matrix for the first time.Scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray polycrystalline diffraction(XRD)and other methods were used to characterize the materials.The electrochemical behavior and electrocatalytic performance of Co-MOF-74@MC on pyrazinamide(PZA)and isoniazid(INZ)were also studied.Compared with a single component,the composite material combines the advantages of Co-MOF-74 and MC,with high electrical conductivity,good electrochemical stability,and excellent electrocatalytic performance.The electrochemical sensor based on Co-MOF-74@MC shows high sensitivity for the determination of PZA,and the detection of INZ has a low overpotential and a relatively wide linear range.The sensor can be used for the analysis of pyrazinamide and isoniazid in actual serum and urine samples.2.A new bimetallic metal-organic framework MOF-818 and reduced graphene oxide/multi-wall carbon nanotube composites(MOF-818@RGO/MWCNTs)were successfully synthesized by a simple solvothermal method.A series of methods were used to study the structure of the composites and the electrocatalytic properties of the composites tocoffeic acid(CA),chlorogenic acid(CGA)and gallic acid(GA).The results show that the composite has hierarchical porous structures,good electrical conductivity and abundant active sites,and the synergistic effect of MOF-818 and RGO/MWCNTs also gives MOF-818@RGO/MWCNTs excellent electrocatalytic performance.The sensors based on MOF-818@RGO/MWCNTs show excellent electrocatalytic activity against CA,CGA and GA.The sensor also shows good reproducibility,stability and practicality.This research can open a new way for the design and construction of highly sensitive electrochemical sensors based on bimetal MOFs with more active sites.